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2007 ASCE/SEI Structures Congress Long Beach, California
Seismic Design Provisions of ASCE/SEI 7-2005 7 2005 Part 3 Robert Bachman Chair, ASCE 7 Seismic Task Committee 2000-2005
R. E. Bachman, h Consulting l i Structurall Engineer i Laguna Niguel, California May 16 16, 2007
Overview • Introduction to Earthquake Engineering • Revised Organization for ASCE 7 – 2005 g per ASCE 7 – 2005 • Seismic Design – – – – –
Basic Criteria Structural Design for Buildings Nonstructural Components in Buildings (Chptr 13) Nonbuilding Structures (Chapter 15) R f References tto M Material t i l Design D i Standards St d d (Ch (Chptr t 14) Brief Discussion on Chapters 16-23 Modifications of ASCE 7-05 in the 2006 IBC 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
2
Nonstructural Components •
Architectural,, Mechanical and Electrical Components p supported pp by or located within buildings or other structures.
•
In 1997 UBC Requirements Located in: Section 1632 Lateral Force on Elements, Nonstructural Components and Equipment Section 1633.2.4.2 Exterior Elements Section 1633.2.8 Anchorage of Concrete and Masonry Walls
•
In 2006 IBC – Refers to ASCE 7-05 including Supplement 1: Ch t 13 – Seismic Chapter S i i D Design i R Requirements i t ffor N Nonstructural t t l Components Section 12.11.2 Anchorage of Concrete and Masonry Structural Walls 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
3
Nonstructural Limits of Applicability •
1997 UBC – Wherever UBC Adopted (Western States) 1. Requirements for the following items apply only in Seismic Zones 2, 3 and 4: 2. Ceilings, light fixtures, connections for prefabricated elements l t other th than th walls, ll exterior t i elements, l t anchorage of concrete or masonry walls.
•
2006 IBC – Applies throughout the US with following exceptions: 1. Mechanical and Electrical Components in SDC A and B 2. Mechanical and Electrical in SDC if Ip = 1.0 3. Architectural in SDC A 4. Architectural in SDC B if Ip = 1.0 except certain parapets
• Other exceptions for light items, piping and ductwork in both NOTE : there is a major errata in ASCE 7 – mechanical and electrical are not exempt if all you do is attached flexible lines to them.
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
4
Nonstructural Demands •
Demands similar in both 1997 UBC and 2006 IBC
•
Equivalent Static Forces – Fp Equation – Independent of building structural properties 1. Strength Level Forces in both codes 2. 2006 IBC provides building dependent option of determining.
•
Relative Displacements for Selected Components 1 Anticipated Relative Displacements at Design 1. Earthquake Level in both codes (Δm or Dp). 2. 2006 IBC provides explicit equations and option of g using g building g structural p properties. p determining 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
5
Nonstructural Force Demand •
1997 UBC – Based on 1994 NEHRP Fp = ap Ca Ip ( 1 + 3 hx ) Wp Rp hr Fp (min) = 0.7 Ca Ip Wp Fp (max) = 4 Ca Ip Wp
•
for Ca = 0.40, Fp = 0.28 IpWp for Ca = 0.40, Fp = 1.60 IpWp
2006 IBC – Based on 1997 NEHRP Fp = 0.4 ap SDS ( 1 + 2 z ) Wp (Rp / Ip ) h Fp (min) = 0.3 SDS Ip Wp Fp (max) = 1.6 1 6 SDS Ip Wp 2007 Structures Congress
for SDS = 1.00, Fp = 0.30 IpWp for SDSS = 1.00, 1 00 Fp = 1.60 1 60 IpWp Seismic Provisions of ASCE/SEI 7-05
6
N Nonstructural l Importance I Factor F - Ip •
Both the 1997 UBC and 2006 IBC have ha e assigned Nonstr Nonstructural ct ral Component Importance Factors, Ip
•
In both codes the values of Ip are either 1.0 or 1.5
•
In the 1997 UBC, the value of Ip is based on the Occupancy Category of the structure or facility
•
In the 2006 IBC, the value of Ip is based 1. Requirements of the component to function after a DBE or 2 Occupancy Category of the structure or facility 2.
•
In the 2006 IBC, nonstructural components/systems which are assigned an Ip = 1.5 are called Designated Seismic Systems. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
7
Nonstructural Component ap and Rp Factors •
Both 1997 UBC and 2006 IBC have ap and Rp factors assigned in tables that are used in Fp equation.
•
The values of ap range g from 1.0 to 2.5 in both codes and values of ap can be taken as less than 2.5 based on dynamic analysis.
•
In the 1997 UBC, Rp values range from 1.0 to 4.0.
•
In the 2000 IBC, Rp values range from 1.0 to 12.0.
•
In both codes, the values of Rp can be assigned based on the y and deformabilityy capacity. p y ductility
•
In the 1997 UBC there are 19 footnotes to the ap and Rp table.
•
In the 2006 IBC there only 2 footnotes to the ap and Rp tables. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
8
Comparison of ap and Rp values for Selected Architectural Components Architectural Component
ap
1997 UBC Rp
2006 IBC ap
Rp
Cantilever Parapets
2.5
3.0
2.5
2.5
E t i Walls* Exterior W ll * (rigid ( i id diaph.) di h )
10 1.0
30 3.0
10 1.0
25 2.5
Partitions* (rigid diaph.)
1.0
3.0
1.0
2.5
Ceilings
1.0
3.0
1.0
2.5
Penthouses (not an extension)
2.5
4.0
2.5
3.5
Signs and Billboards
2.5
3.0
2.5
2.5
Access Floors* (special)
1.0
3.0
1.0
2.5
Storage Cabinets
1.0
3.0
1.0
2.5
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
9
Comparison of Fp/Wp values for Architectural Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 1997 UBC hx = 0 hx = hr
2006 IBC z=0 z=h
Cantilever Parapets
0.33
1.33
0.40
1.20
E t i Walls Exterior W ll
0 28 0.28
0 53 0.53
0 30 0.30
0 48 0.48
Partitions
0.28
0.53
0.30
0.48
Ceilings
0.28
0.53
0.30
0.48
Penthouses (not an extension)
0.28
1.00
0.30
0.86
Signs and Billboards
0.33
1.33
0.40
1.20
Access Floors (special)
0.28
0.53
0.30
0.48
Storage Cabinets
0.28
0.53
0.30
0.48
Architectural Component
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
10
Comparison of ap and Rp values for Selected Mechanical and Electrical Components Mech./Elect. Component
ap
1997 UBC Rp
2006 IBC ap
Rp
Tanks and Vessels w/o skirts
1.0
3.0
1.0
2.5
Ai side Air id equipment i t
10 1.0
30 3.0
25 2.5
60 6.0
Wet side equipment
1.0
3.0
1.0
2.5
Emergency Battery Racks
1.0
3.0
1.0
2.5
Stacks, towers braced below cg
2.5
3.0
2.5
3.0
Vibration Isolated Equipment*
2.5
1.5
2.5
2.0 – 2.5
Piping – ASME Welded
1.0
3.0
2.5
12.0
Piping – threaded joints
1.0
3.0
2.5
4.5
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
11
Comparison of Fp/Wp values for Mech./Elect. Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 Mech./Elect. Component
1997 UBC hx = 0 hx = hr
2006 IBC z=0 z=h
Tanks and Vessels w/o skirts
0.28
0.53
0.30
0.48
Ai side Air id equipment i t
0 28 0.28
0 53 0.53
0 30 0.30
0 50 0.50
Wet side equipment
0.28
0.53
0.30
0.48
Emergency Batteries/Tanks
0.28
0.53
0.30
0.48
Stacks, towers braced below cg
0.33
1.33
0.33
1.00
Vibration Isolated Equipment*
0.67
1.60
Piping – ASME Welded
0.28
0.53
0.30
0.30
Piping – threaded joints
0.28
0.53
0.30
0.67
2007 Structures Congress
0.40-0.50
1.20-1.50
Seismic Provisions of ASCE/SEI 7-05
12
Comparison of ap and Rp values for Selected Architectural Components ASCE 7-02 ap Rp
ASCE 7-05 ap Rp
Cantilever Parapets
2.5
2.5
2.5
2.5
Exterior Walls* (rigid diaph.)
1.0
2.5
1.0
2.5
Partitions* (rigid diaph.)
1.0
2.5
1.0
2.5
Ceilings
10 1.0
25 2.5
10 1.0
25 2.5
Penthouses (not an extension)
2.5
3.5
2.5
3.5
Si Signs and d Billboards Billb d
25 2.5
25 2.5
25 2.5
25 2.5
Access Floors* (special)
1.0
2.5
1.0
2.5
Storage Cabinets
1.0
2.5
1.0
2.5
Architectural Component
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
13
Comparison of ap and Rp values for Selected Architectural Components ASCE 7-02 ap Rp
ASCE 7-05 ap Rp
Cantilever Parapets
2.5
2.5
2.5
2.5
Exterior Walls* (rigid diaph.)
1.0
2.5
1.0
2.5
Partitions* (rigid diaph.)
1.0
2.5
1.0
2.5
Ceilings
10 1.0
25 2.5
10 1.0
25 2.5
Penthouses (not an extension)
2.5
3.5
2.5
3.5
Si Signs and d Billboards Billb d
25 2.5
25 2.5
25 2.5
25 2.5
Access Floors* (special)
1.0
2.5
1.0
2.5
Storage Cabinets
1.0
2.5
1.0
2.5
Architectural Component
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
14
Comparison of Fp/Wp values for Architectural Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 ASCE 7-05 z=0 z= h
ASCE 7-05 z=0 z=h
Cantilever Parapets
0.40
1.20
0.40
1.20
E t i Walls Exterior W ll
0 30 0.30
0 48 0.48
0 30 0.30
0 48 0.48
Partitions
0.30
0.48
0.30
0.48
Ceilings
0.30
0.48
0.30
0.48
Penthouses (not an extension)
0.30
0.86
0.30
0.86
Signs and Billboards
0.40
1.20
0.40
1.20
Access Floors (special)
0.30
0.48
0.30
0.48
Storage Cabinets
0.30
0.48
0.30
0.48
Architectural Component
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
15
Comparison of ap and Rp values for Selected Mechanical and Electrical Components Mech./Elect. Component
ap
ASCE 7-02 Rp
ASCE 7-05 ap Rp
Tanks and Vessels w/o skirts
1.0
2.5
1.0
2.5
Ai side Air id equipment i t
10 1.0
25 2.5
25 2.5
60 6.0
Wet side equipment
1.0
2.5
1.0
2.5
Emergency Battery Racks
1.0
2.5
1.0
2.5
Stacks, towers braced below cg
2.5
2.5
2.5
3.0
Vibration Isolated Equipment*
2.5
2.5
2.5
2.0 – 2.5
Piping – ASME Welded
1.0
3.5
2.5
12.0
Piping – threaded joints
1.0
2.5
2.5
4.5
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
16
Comparison of Fp/Wp values for Mech./Elect. Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 ASCE 7-02 z=0 z= h
ASCE 7-05 z=0 z=h
Tanks and Vessels w/o skirts
0.30
0.48
0.30
0.48
Ai side Air id equipment i t
0 30 0.30
0 48 0.48
0 30 0.30
0 50 0.50
Wet side equipment
0.30
0.48
0.30
0.48
Emergency Batteries/Tanks
0.30
0.48
0.30
0.48
Stacks, towers braced below cg
0.40
1.20
0.33
1.00
Vibration Isolated Equipment*
0.40
1.20
Piping – ASME Welded
0.30
0.34
0.30
0.30
Piping – threaded joints
0.30
0.48
0.30
0.67
Mech./Elect. Component
2007 Structures Congress
0.40-0.50
1.20-1.50
Seismic Provisions of ASCE/SEI 7-05
17
Nonstructural Relative Displacement Demand •
ASCE 7-05 – Maximum Relative Displacements for DBE level motions are to be considered
•
In ASCE 7-05 Required for Architectural Components which pose a life safety hazard including exterior wall elements and glazing Required q for Mech/Elect components p and systems y where Ip greater than 1.0.
•
Except for glazing – no specific acceptance criteria is provided N requirement No i to stay within i hi elastic l i lilimits i or allowables ll bl
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
18
Nonstructural Relative Displacement Demand •
In both 1997 UBC and 2006 IBC – Maximum Relative Di l Displacements ffor DBE llevell motions i are to b be considered id d
•
In 1997 UBC Required to be considered for equipment attachments for Essential and Hazardous Facilities Deformation Compatibility in Exterior Elements
•
I 2006 IBC In Required for Architectural Components which pose a life safety hazard including exterior wall elements and glazing Required for Mech/Elect components and systems where Ip greater than 1.0.
•
Except for glazing – no specific acceptance criteria is provided No requirement to stay within elastic limits or allowables 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
19
Load Combinations •
In both codes, strength, ASD and alternate ASD load combinations are provided.
•
In both codes codes, there are Eh and Ev loads. loads
•
In the 1997 UBC Ev may be taken as zero for the alternate ASD load combinations. In the 2006 IBC, Ev is used and not taken as zero for f exceptt for f foundation f d ti sizing. i i
•
In both codes, the redundancy factor, ρ, is specified as 1.0 for p nonstructural components.
•
In both codes, Ωo is not specified and load combinations with Ωo are not used with nonstructural components (including penthouses) 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
20
Anchorage of Nonstructural Components •
In the 1997 UBC 1. Special p Requirements q for shallow anchors. Rp = 1.5 Shallow anchors defined as embed/diameter less than 8 2. Special Requirement for expansion anchors for vibration isolated equipment – 2 Fp SEAOC Bluebook only if gap > 0.25 in 3. Section 1923 – Anchorage to concrete - Strength 2.0 factor if no special inspection – 1.3 with special insp.
•
In the 2006 IBC 1. All anchor forces based on Rp of 1.5 unless: - Anchorage governed by ductile steel element or - Post installed for Seismic Applications per ACI 355.2 or - Anchors design in accordance with ACI 318-05, App. D 2. Additional 1.3 factor or maximum transferable force 3. Special requirement – vib iso equipment – 2 Fp if gap > 0.25” 4 L 4. Load d path th analysis l i to t primary i structure t t shall h ll be b performed. f d 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
21
Design and Detailing Requirements of Architectural Components •
In 1997 UBC 1. Specific demands exterior walls and connections 2. UBC Standard 25-2, Part III for lay-in ceilings
•
In 2006 IBC 1. 2. 3 3. 4. 5.
Specific demands exterior walls and connections Suspending Ceilings – CISCA & ASTM standards Glazing – Drift capacity AAMA 501 501.6 6 Access Floors – special access floor details Tall Partitions – independent bracing 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
22
Design and Detail Requirements for Mechanical and Electrical Equipment •
In 1997 – No specific requirements
•
In 2006 IBC 1. Sprinkler systems – NFPA 13 with amendments 2. Escalators and Elevators – ASME A17.1 3. Vessels – ASME B& PV 4. Piping – ASCE B 31.1 5. HVAC Ducting – (SMACNA not specifically referenced) 6 Lighting fixtures – Prescriptive detail requirements 6. 7. Many specific prescriptive details for Mechanical and Electrical Equipment – Section 13.6.5.5
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
23
Special Certification Requirements for Certain Designated Seismic Systems (Ip=1.5) •
In 1997 UBC – No specific requirement
•
In 2006 IBC - Seismic qualification required for 1 Active mechanical and electrical equipment that are 1. required to function following a DBE 2. Components containing hazardous contents
•
Qualification to demonstrate functionality after being subject to a DBE to be determined by either: 1. Shake table testing – ICC-ES AC-156 , 2004 2. Experience Data 3. Analysis (extremely difficult for active equipment)
•
Certification required by supplier indicating compliance 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
24
Final Comments about Nonstructural Components • Force levels and approaches similar between 1997 UBC and 2006 IBC. Terminology is similar. • Much more implementation detail in the 2006 IBC • Additional documentation requirements q in the 2006 IBC • Much more QA requirements in the 2006 IBC. Note there are specific requirements for supports and attachments to be shown on the construction documents documents. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
25
Nonbuilding g Structures •
Self supporting structures other than buildings that support gravity loads and resist overturning moments at their base.
•
In 1997 UBC Requirements located in: Section 1634 Nonbuilding Structures Section 1629 Criteria Selection Section 1630 Minimum Design Lateral Forces…
•
In 2006 IBC – Refers to ASCE 7-05 including Supplement 1 Chapter 15 - Seismic Design Requirements for Nonbuilding Structures Chapter 12 - Seismic Design Requirements for Building Structures Chapter p 13 - Seismic Design g Requirements q for Nonstructural Components 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
26
Two Types of Nonbuilding Structures • In both 1997 UBC and 2006 IBC there are two types of nonbuilding structures 1. Those that have seismic force resisting systems that are similar to buildings (e.g. pipe racks) 2. Those that do not have seismic force resisting systems that are similar to a building (e.g. flat bottom tanks)
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
27
Example p of a “Similar” System y
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
28
Example of a “Not Similar” System
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
29
Nonbuilding Structures Limits of Applicability •
1997 UBC – Wherever UBC Adopted (Western States) 1. Not required in Seismic Zone 0 but everywhere else 2. For structures similar to building – same restrictions as for b ildi structures building t t with ith similar i il systems. t 3. For structures not similar to buildings – no restrictions.
•
2006 IBC C – applies throughout the US S with ffollowing exceptions: 1. Not required for Seismic Design Category A except Sec11.7 2. For structures similar to building – same restrictions as for building structures with similar systems but with additional options. 3. For structures not similar to buildings – some restrictions 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
30
Nonbuilding Structure Demands •
In both codes – same base shear equations used for building structures. Basically the same equation in the 1997 UBC and 2006 IBC except for site ground motion terminology. However, the R values, I values and minimum values are significantly different in the two codes. Also the 2006 IBC C specifies f Ωo and Cd values, detailing requirements along with height limits and restrictions for all systems while the 1997 UBC only specifies R and Ωo values values. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
31
Equivalent Lateral Force Equations for Structures with Systems Similar to Buildings 1997 UBC
2006 IBC
( Ts = Cv / 2.5 Ca )
( Ts = SD1 / SDS )
T < Ts
V = Ca I W R
V = SDS W (R / I)
T > Ts
V = Cv I W RT
V= T > TL
SD1 W (R / I ) T
V = SD1TL W (R / I ) T2
Min V
V = 0.11 CaI W
V = 0.01 W
Min Zone 4 (S1 > 0.6)
V = 0.8 Z NV I W R
V = 0.5 S1 W (R / I )
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Equivalent Lateral Force Equations for Structures with Systems Not Similar to Buildings 1997 UBC
2006 IBC
( Ts = Cv / 2.5 Ca )
( Ts = SD1 / SDS )
T < Ts
V = Ca I W R
V = SDS W (R / I)
T > Ts
V = Cv I W RT
V= T > TL
SD1 W (R / I ) T
V = SD1TL W (R / I ) T2
Min V
V = 0.56 CaI W
V = 0.03 W
Min Zone 4 (S1 > 0.6)
V = 1.6 Z NV I W R
V = 0.8 S1 W (or 0.5 S1 W ) (R / I ) (R / I )
2007 Structures Congress
(or 0.01 W)
Seismic Provisions of ASCE/SEI 7-05
33
Comparison of Minimum Values For Structures Not Similar to Buildings •
To Compare – assume a rock site with I =1.0 1997 UBC Z = 0.4, Ca = 0.40, Nv = 1.0, Cv = 0.4 and 2006 IBC
SDS = 1.0, S1 = 0.60, SD1 = 0.40
1997 UBC V min
2006 IBC
R=2.2
R=3.6
R= 2.2*
R=3.6*
0.22 W
0.22 W
0.03 W
0.03 W
(or 0.01W)
(or 0.01W)
Zone 4 V min 0.29 W
0.17 W
0.22 W
0.13 W
(or 0.14W) (or 0.08W) *For Comparison Only 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
34
Nonbuilding Structure Importance Factor I • B Both th the th 1997 UBC and d 2006 IBC h have assigned i d Seismic Importance Factors, I. • IIn the th 1997 UBC, UBC th the value l off I iis either ith 1 1.0 0 or 1 1.25 25 and is based on the Occupancy Category. • In the 2006 IBC IBC, the value of I is either 1 1.0, 0 1 1.25 25 or 1.5 and is based on largest value from: 1. Referenced standards for the structure type 2. Occupancy Category (Table 11.5-1) 3. Specified values in Chapter 15 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
35
Nonbuilding g Structures Similar to Buildings g R Factors and Height Limits •
In the 1997 UBC,, R,, Ωo and height g limits are the same as for building structures with 2 exceptions: 1. Concrete IMRFs permitted to height of 50 feet rather than NP in Zones 3 and 4 if R is taken as 2 2.8 8 rather than 5 5.5 5 2. Height limits may be increased by 50% if regular structures that are not occupied or accessible to general public
•
In the 2006 IBC, the R, Ωo, Cd and height limits are same as for building structures with additional options: 1. Height limits of certain systems are permitted to higher levels if lower R values are used (see next slide) 2. SCBF and special shear wall height limits can be increased by 50 % if regular structures with multiple lines of resistance – same as permitted for buildings 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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“Similar” Nonbuilding Structure Options p Ordinary Steel Concentrically Braced Frames System
Detailing
R
Height Limit (ft.) B
C
D
E
F
35
35
NP
Steel OCBFs
AISC 341
3.25
NL
NL
With Permitted Height Increase
AISC 341
2.5
NL
NL 160 160 100
With Unlimited Height
AISC 360
1.5
NL
NL
2007 Structures Congress
NL
NL NL
Seismic Provisions of ASCE/SEI 7-05
37
“Similar” Similar Nonbuilding Structure Options Intermediate Moment Frames of Steel System
Detailing
R
Height Limit (ft.) B
C
D
E
F
35
NP NP
Steel IMFs
AISC 341
4.5
NL
NL
With Permitted Height Increase
AISC 341
2.5
NL
NL 160 160 100
With Unlimited Height
AISC 341
1.5
NL
NL
2007 Structures Congress
NL
NL NL
Seismic Provisions of ASCE/SEI 7-05
38
“Similar” Similar Nonbuilding Structure Options Ordinary Moment Frames of Steel System
Detailing
R
Height Limit (ft.) B
C
D
E
F
NP NP
Steel OMFs
AISC 341
3.5
NL
NL
NP
With Permitted Height Increase
AISC 341
2.5
NL
NL
100 100 NP
With Unlimited Height
AISC 360
1.0
NL
NL
NL
2007 Structures Congress
NL NL
Seismic Provisions of ASCE/SEI 7-05
39
“Similar” Nonbuilding Structure Options p Intermediate Reinforced Concrete Moment Frames System
Detailing
R
Height Limit (ft.) B C D E F
Concrete IMFs
ACI 318 5.0 with Chptr. 21
NL
NL
NP
NP NP
With Permitted Height Increase
ACI 318 3.0 with Chptr. 21
NL
NL
50
50
With Unlimited Height
ACI 318 0.8 with Chptr. 21
NL
NL
NL
NL NL
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
50
40
“Similar” Nonbuilding Structure Options p Ordinary Reinforced Concrete Moment Frames System
Detailing
R
Height Limit (ft.) B
C
D
E
F
Concrete OMFs
ACI 318 NOT with ith Ch Chptr. t 21
3.0
NL
NL
NP
NP NP
With Permitted Height Increase
ACI 318 NOT 0.8 with Chptr. 21
NL
NL
50
50
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
50
41
Comparison of Selected “Not Not Similar” Similar Nonbuilding Structure R values Structure Type Skirt Supported Vessels Cast in Place Silos T k and Tanks d Pressurized P i dS Spheres h Cooling Towers Bins and Hoopers Signs and Bill Boards Amusement Structures/Monuments Trussed Towers 2007 Structures Congress
R value 1997 UBC 2006 IBC 2.9 3.6 2 2.2 2 3.6 2.9 3.6 2.2 2 2.9 9
2 or 3 3.5 2 or 3 3.5 3.0 3.5 2.0 3 3.0 0
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Nonstuructural Component or Nonbuilding Structure? • Sometimes its confusing whether one should use the nonbuilding structure or nonstructural component requirements. • Particularly confusing are tanks, vessels, signs and bill boards b d where h the h requirements i show h up in i 2 places. • Where Wh duplicative, d li ti if it can typically t i ll fit in i or on a building (10 feet tall or less) suggest using nonstructural requirements. requirements 2007 Structures Congress
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Load Combinations •
In both codes, strength, ASD and alternate ASD load combinations are provided.
•
In both codes codes, there are Eh and Ev loads. loads
•
In the 1997 UBC Ev may be taken as zero for the alternate ASD load combinations. In the 2006 IBC, Ev is used and not taken as zero for f exceptt for f foundation f d ti sizing. i i
•
In both codes, redundancy factor, ρ, is specified as 1.0 for “not g structures. Same as buildings g for “similar”. similar” nonbuilding
•
In both codes, Ωo is specified. However in the 1997 UBC not really explained how to use but its explained to a certain extent in the 2006 for some nonbuilding structures. 2007 Structures Congress
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Fundamental Period Determination For Nonbuilding Structures •
In 1997 UBC – Requires that period be determined by rational methods such as Method B (Rayleigh approach).
•
In 1999 SEAOC Bluebook states Method A should not apply to both “similar” and “not similar” nonbuilding structures. Suggests Rayleigh approach or dynamic analysis analysis. BB Section C 109 109.1.4 14
•
In 2006 IBC – Fundamental Period to be determined by rational building type procedures or by the Rayleigh formula – Specifically excludes Method A type procedures to be used in determining the period of nonbuilding structures.
2007 Structures Congress
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Design and Detailing Requirement for Structures “Similar” to Buildings •
In 1997 UBC – No specific additional requirements provided
•
In 2006 IBC 1. Same requirements as for buildings except where noted 2. Steel Storage Racks – RMI plus additional requirements 3. Towers supporting tanks and vessels – added requirements 4. Piers and wharves – only for those accessible to the public
2007 Structures Congress
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Design and Detailing Requirement for Structures “Not Similar” to Buildings •
In 1997 UBC – Use approve national standards with limit that the that the total base shear overturning moment determined by them can not be less than 80 % of the UBC determined value.
•
In 2006 IBC – Some requirements provided for the following 1. Earth Retaining Structures 2. Secondary Containment Structures 3. Flat Bottom Tanks - AWWA 100, API 650, ACI 313 4. Elevated Tanks for Liquids and Granular Material 5. Boilers and Pressure Vessels – ASME BPVC 6. Liquid and Gas Spheres/ Refrigerated – ASME BPVC & API 7. Horizontal Vessels 2007 Structures Congress
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Final Comments About Nonbuilding Structures • Approaches between 1997 UBC and 2006 IBC similar. • Force levels, height limits and detailing requirements for structures “similar” to buildings very different between codes. • Forces levels for structures “not similar” to buildings very similar except for I factors. • More detailing requirements provided in the 2006 IBC. 2007 Structures Congress
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Chapter 14 Material Specific Requirements ((Trumped p by y IBC Chapters p 18-23)) 1. Steel: references plus light frame 2. Concrete: reference plus selected details p and section on piles 3. Composite steel and concrete: references 4 Masonry: references plus selected details 4. 5. Wood: references plus selected details 2007 Structures Congress
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Chapter 16 Response History Analysis • Provides Requirements for Selection and Scaling of Ground Motion Time Histories – virtually the same as those found in the UBC • Provides requirements for performing nonlinear response history analysis (Note: time history analysis = response history analysis)
• Similar to the UBC requirements q but with a few additional requirements.
2007 Structures Congress
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Chapters 17 - 19 • Chapter 17 – Seismic Isolation Requirements - basically the same as UBC excepts for: * ground motions * RI values and height limits • Chapter 18 – Brand new Chapter on Structures with Damping Systems – Based on NEHRP • Chapter 19 – Soil Str Structure ct re Interaction – Really Reall developed for large structures with rigid bases ((e.g. g nuclear reactor containment structures)) 2007 Structures Congress
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Chapter 20 Site Classification Procedure • Intended primarily for Geotechnical Engineers • Provides Detailed Procedures for Determining Site Class A – F • Similar Si il to t what h t is i in i the th 1997 UBC • Provides specific Details for how to deal with Site Cl F andd how Class h to t deal d l with ith refusal f l if a rockk layer is met at a depth of less than 100 feet. 2007 Structures Congress
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Chapter 21 Site Specific Ground Motion Procedures •
•
Specific Procedures Provided for both - Site Response Analysis - Ground Motion Hazard Analysis Limits provided on site specific determined spectra - Can be greater than map determined spectra including soil amplification lifi ti effects ff t - Can’t be less than 80% of map determined spectra including soil amplification effects. - Site Class F site specific spectra can’t be less than 80% of the map determined spectra including soil amplification effects if the site were classified Site Class E. 2007 Structures Congress
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Chapter 22 Ground Motion Maps • Maps provided for Ss and S1 on soft rock and the long period transition TL • Use for f cursory checks, h k not recommended d d ffor design • For design use the USGS web site (or CD which is coming) based on longitude and latitude of site (not zip code) determined to 3 digits beyond decimal. http://earthquake.usgs.gov/research/hazmaps/design/index.php 2007 Structures Congress
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Chapter 23 Seismic Design References • Same as Chapters 35 in IBC and UBC • Ch Chapter t 35 iin IBC T Trumps IBC if there th is i a difference. diff For F example AISC 341 is referenced in Chapter 23 while in the IBC its AISC 341-05 including Supplement No. 1. • The seismic forces specified in ASCE 7-05 are tied to the detailed reference documents. Not using the detailing specified ifi d in i the th IBC including i l di any modifications difi ti means the th specified seismic forces may not be valid.
2007 Structures Congress
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Appendix 11A Quality Assurance Provisions • Provides testing and inspection requirements for structures and nonstructural components • Not adopted typically by jurisdictions. Instead use Chapter 17 of the IBC. • Includes a description of a quality assurance plan that needs to be developed.
2007 Structures Congress
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Appendix 11B Existing Building Provisions • Provides triggering requirements for structural independent and dependent additions, alterations and change of use • Not adopted typically by jurisdictions. Instead use Chapter h 34 off the h IBC or llocally ll adopted d d ordinances.
2007 Structures Congress
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2006 IBC Modifications to ASCE 7-05 • 2006 IBC S Section ti 1613 1613.6 6P Permits it C Certain t i Less L Restrictive R t i ti Alternatives to be used than those found in ASCE 7-05 1. Assumption of flexible diaphragms – provides additional conditions when diaphragms may be considered flexible 2. Permits steel OMFs and OCBFs to be used with seismic isolation for structures assigned SDC D, E and F if RI is taken as 1.0 (currently not permitted since isolation limits tied to R table).
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Concluding Remarks • Seismic Provisions of ASCE 7-05 represent our best current seismic design practice • Consistency C i with i h all ll the h latest l material i l codes d – big bi improvement from the UBC • Reorganization and reformat of seismic provisions should greatly improve usability • Seismic forces in most cases will be similar or less than those h specified ifi d in i the h 1997 199 UBC C because b off the h convergence strategy that SEAOC used in developing the q 1997 UBC seismic requirements. 2007 Structures Congress
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Seismic Design Provisions of ASCE/SEI 7-2005 7 2005 Part 3 Robert Bachman Chair, ASCE 7 Seismic Task Committee 2000-2005
R. E. Bachman, h Consulting l i Structurall Engineer i Laguna Niguel, California May 16 16, 2007
Overview • Introduction to Earthquake Engineering • Revised Organization for ASCE 7 – 2005 g per ASCE 7 – 2005 • Seismic Design – – – – –
Basic Criteria Structural Design for Buildings Nonstructural Components in Buildings (Chptr 13) Nonbuilding Structures (Chapter 15) R f References tto M Material t i l Design D i Standards St d d (Ch (Chptr t 14) Brief Discussion on Chapters 16-23 Modifications of ASCE 7-05 in the 2006 IBC 2007 Structures Congress
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Nonstructural Components •
Architectural,, Mechanical and Electrical Components p supported pp by or located within buildings or other structures.
•
In 1997 UBC Requirements Located in: Section 1632 Lateral Force on Elements, Nonstructural Components and Equipment Section 1633.2.4.2 Exterior Elements Section 1633.2.8 Anchorage of Concrete and Masonry Walls
•
In 2006 IBC – Refers to ASCE 7-05 including Supplement 1: Ch t 13 – Seismic Chapter S i i D Design i R Requirements i t ffor N Nonstructural t t l Components Section 12.11.2 Anchorage of Concrete and Masonry Structural Walls 2007 Structures Congress
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Nonstructural Limits of Applicability •
1997 UBC – Wherever UBC Adopted (Western States) 1. Requirements for the following items apply only in Seismic Zones 2, 3 and 4: 2. Ceilings, light fixtures, connections for prefabricated elements l t other th than th walls, ll exterior t i elements, l t anchorage of concrete or masonry walls.
•
2006 IBC – Applies throughout the US with following exceptions: 1. Mechanical and Electrical Components in SDC A and B 2. Mechanical and Electrical in SDC if Ip = 1.0 3. Architectural in SDC A 4. Architectural in SDC B if Ip = 1.0 except certain parapets
• Other exceptions for light items, piping and ductwork in both NOTE : there is a major errata in ASCE 7 – mechanical and electrical are not exempt if all you do is attached flexible lines to them.
2007 Structures Congress
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Nonstructural Demands •
Demands similar in both 1997 UBC and 2006 IBC
•
Equivalent Static Forces – Fp Equation – Independent of building structural properties 1. Strength Level Forces in both codes 2. 2006 IBC provides building dependent option of determining.
•
Relative Displacements for Selected Components 1 Anticipated Relative Displacements at Design 1. Earthquake Level in both codes (Δm or Dp). 2. 2006 IBC provides explicit equations and option of g using g building g structural p properties. p determining 2007 Structures Congress
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Nonstructural Force Demand •
1997 UBC – Based on 1994 NEHRP Fp = ap Ca Ip ( 1 + 3 hx ) Wp Rp hr Fp (min) = 0.7 Ca Ip Wp Fp (max) = 4 Ca Ip Wp
•
for Ca = 0.40, Fp = 0.28 IpWp for Ca = 0.40, Fp = 1.60 IpWp
2006 IBC – Based on 1997 NEHRP Fp = 0.4 ap SDS ( 1 + 2 z ) Wp (Rp / Ip ) h Fp (min) = 0.3 SDS Ip Wp Fp (max) = 1.6 1 6 SDS Ip Wp 2007 Structures Congress
for SDS = 1.00, Fp = 0.30 IpWp for SDSS = 1.00, 1 00 Fp = 1.60 1 60 IpWp Seismic Provisions of ASCE/SEI 7-05
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N Nonstructural l Importance I Factor F - Ip •
Both the 1997 UBC and 2006 IBC have ha e assigned Nonstr Nonstructural ct ral Component Importance Factors, Ip
•
In both codes the values of Ip are either 1.0 or 1.5
•
In the 1997 UBC, the value of Ip is based on the Occupancy Category of the structure or facility
•
In the 2006 IBC, the value of Ip is based 1. Requirements of the component to function after a DBE or 2 Occupancy Category of the structure or facility 2.
•
In the 2006 IBC, nonstructural components/systems which are assigned an Ip = 1.5 are called Designated Seismic Systems. 2007 Structures Congress
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Nonstructural Component ap and Rp Factors •
Both 1997 UBC and 2006 IBC have ap and Rp factors assigned in tables that are used in Fp equation.
•
The values of ap range g from 1.0 to 2.5 in both codes and values of ap can be taken as less than 2.5 based on dynamic analysis.
•
In the 1997 UBC, Rp values range from 1.0 to 4.0.
•
In the 2000 IBC, Rp values range from 1.0 to 12.0.
•
In both codes, the values of Rp can be assigned based on the y and deformabilityy capacity. p y ductility
•
In the 1997 UBC there are 19 footnotes to the ap and Rp table.
•
In the 2006 IBC there only 2 footnotes to the ap and Rp tables. 2007 Structures Congress
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Comparison of ap and Rp values for Selected Architectural Components Architectural Component
ap
1997 UBC Rp
2006 IBC ap
Rp
Cantilever Parapets
2.5
3.0
2.5
2.5
E t i Walls* Exterior W ll * (rigid ( i id diaph.) di h )
10 1.0
30 3.0
10 1.0
25 2.5
Partitions* (rigid diaph.)
1.0
3.0
1.0
2.5
Ceilings
1.0
3.0
1.0
2.5
Penthouses (not an extension)
2.5
4.0
2.5
3.5
Signs and Billboards
2.5
3.0
2.5
2.5
Access Floors* (special)
1.0
3.0
1.0
2.5
Storage Cabinets
1.0
3.0
1.0
2.5
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Comparison of Fp/Wp values for Architectural Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 1997 UBC hx = 0 hx = hr
2006 IBC z=0 z=h
Cantilever Parapets
0.33
1.33
0.40
1.20
E t i Walls Exterior W ll
0 28 0.28
0 53 0.53
0 30 0.30
0 48 0.48
Partitions
0.28
0.53
0.30
0.48
Ceilings
0.28
0.53
0.30
0.48
Penthouses (not an extension)
0.28
1.00
0.30
0.86
Signs and Billboards
0.33
1.33
0.40
1.20
Access Floors (special)
0.28
0.53
0.30
0.48
Storage Cabinets
0.28
0.53
0.30
0.48
Architectural Component
2007 Structures Congress
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Comparison of ap and Rp values for Selected Mechanical and Electrical Components Mech./Elect. Component
ap
1997 UBC Rp
2006 IBC ap
Rp
Tanks and Vessels w/o skirts
1.0
3.0
1.0
2.5
Ai side Air id equipment i t
10 1.0
30 3.0
25 2.5
60 6.0
Wet side equipment
1.0
3.0
1.0
2.5
Emergency Battery Racks
1.0
3.0
1.0
2.5
Stacks, towers braced below cg
2.5
3.0
2.5
3.0
Vibration Isolated Equipment*
2.5
1.5
2.5
2.0 – 2.5
Piping – ASME Welded
1.0
3.0
2.5
12.0
Piping – threaded joints
1.0
3.0
2.5
4.5
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Comparison of Fp/Wp values for Mech./Elect. Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 Mech./Elect. Component
1997 UBC hx = 0 hx = hr
2006 IBC z=0 z=h
Tanks and Vessels w/o skirts
0.28
0.53
0.30
0.48
Ai side Air id equipment i t
0 28 0.28
0 53 0.53
0 30 0.30
0 50 0.50
Wet side equipment
0.28
0.53
0.30
0.48
Emergency Batteries/Tanks
0.28
0.53
0.30
0.48
Stacks, towers braced below cg
0.33
1.33
0.33
1.00
Vibration Isolated Equipment*
0.67
1.60
Piping – ASME Welded
0.28
0.53
0.30
0.30
Piping – threaded joints
0.28
0.53
0.30
0.67
2007 Structures Congress
0.40-0.50
1.20-1.50
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Comparison of ap and Rp values for Selected Architectural Components ASCE 7-02 ap Rp
ASCE 7-05 ap Rp
Cantilever Parapets
2.5
2.5
2.5
2.5
Exterior Walls* (rigid diaph.)
1.0
2.5
1.0
2.5
Partitions* (rigid diaph.)
1.0
2.5
1.0
2.5
Ceilings
10 1.0
25 2.5
10 1.0
25 2.5
Penthouses (not an extension)
2.5
3.5
2.5
3.5
Si Signs and d Billboards Billb d
25 2.5
25 2.5
25 2.5
25 2.5
Access Floors* (special)
1.0
2.5
1.0
2.5
Storage Cabinets
1.0
2.5
1.0
2.5
Architectural Component
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Comparison of ap and Rp values for Selected Architectural Components ASCE 7-02 ap Rp
ASCE 7-05 ap Rp
Cantilever Parapets
2.5
2.5
2.5
2.5
Exterior Walls* (rigid diaph.)
1.0
2.5
1.0
2.5
Partitions* (rigid diaph.)
1.0
2.5
1.0
2.5
Ceilings
10 1.0
25 2.5
10 1.0
25 2.5
Penthouses (not an extension)
2.5
3.5
2.5
3.5
Si Signs and d Billboards Billb d
25 2.5
25 2.5
25 2.5
25 2.5
Access Floors* (special)
1.0
2.5
1.0
2.5
Storage Cabinets
1.0
2.5
1.0
2.5
Architectural Component
2007 Structures Congress
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Comparison of Fp/Wp values for Architectural Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 ASCE 7-05 z=0 z= h
ASCE 7-05 z=0 z=h
Cantilever Parapets
0.40
1.20
0.40
1.20
E t i Walls Exterior W ll
0 30 0.30
0 48 0.48
0 30 0.30
0 48 0.48
Partitions
0.30
0.48
0.30
0.48
Ceilings
0.30
0.48
0.30
0.48
Penthouses (not an extension)
0.30
0.86
0.30
0.86
Signs and Billboards
0.40
1.20
0.40
1.20
Access Floors (special)
0.30
0.48
0.30
0.48
Storage Cabinets
0.30
0.48
0.30
0.48
Architectural Component
2007 Structures Congress
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Comparison of ap and Rp values for Selected Mechanical and Electrical Components Mech./Elect. Component
ap
ASCE 7-02 Rp
ASCE 7-05 ap Rp
Tanks and Vessels w/o skirts
1.0
2.5
1.0
2.5
Ai side Air id equipment i t
10 1.0
25 2.5
25 2.5
60 6.0
Wet side equipment
1.0
2.5
1.0
2.5
Emergency Battery Racks
1.0
2.5
1.0
2.5
Stacks, towers braced below cg
2.5
2.5
2.5
3.0
Vibration Isolated Equipment*
2.5
2.5
2.5
2.0 – 2.5
Piping – ASME Welded
1.0
3.5
2.5
12.0
Piping – threaded joints
1.0
2.5
2.5
4.5
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Comparison of Fp/Wp values for Mech./Elect. Components for Ca = 0.40, SDS = 1.0, Ip = 1.0 ASCE 7-02 z=0 z= h
ASCE 7-05 z=0 z=h
Tanks and Vessels w/o skirts
0.30
0.48
0.30
0.48
Ai side Air id equipment i t
0 30 0.30
0 48 0.48
0 30 0.30
0 50 0.50
Wet side equipment
0.30
0.48
0.30
0.48
Emergency Batteries/Tanks
0.30
0.48
0.30
0.48
Stacks, towers braced below cg
0.40
1.20
0.33
1.00
Vibration Isolated Equipment*
0.40
1.20
Piping – ASME Welded
0.30
0.34
0.30
0.30
Piping – threaded joints
0.30
0.48
0.30
0.67
Mech./Elect. Component
2007 Structures Congress
0.40-0.50
1.20-1.50
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Nonstructural Relative Displacement Demand •
ASCE 7-05 – Maximum Relative Displacements for DBE level motions are to be considered
•
In ASCE 7-05 Required for Architectural Components which pose a life safety hazard including exterior wall elements and glazing Required q for Mech/Elect components p and systems y where Ip greater than 1.0.
•
Except for glazing – no specific acceptance criteria is provided N requirement No i to stay within i hi elastic l i lilimits i or allowables ll bl
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Nonstructural Relative Displacement Demand •
In both 1997 UBC and 2006 IBC – Maximum Relative Di l Displacements ffor DBE llevell motions i are to b be considered id d
•
In 1997 UBC Required to be considered for equipment attachments for Essential and Hazardous Facilities Deformation Compatibility in Exterior Elements
•
I 2006 IBC In Required for Architectural Components which pose a life safety hazard including exterior wall elements and glazing Required for Mech/Elect components and systems where Ip greater than 1.0.
•
Except for glazing – no specific acceptance criteria is provided No requirement to stay within elastic limits or allowables 2007 Structures Congress
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Load Combinations •
In both codes, strength, ASD and alternate ASD load combinations are provided.
•
In both codes codes, there are Eh and Ev loads. loads
•
In the 1997 UBC Ev may be taken as zero for the alternate ASD load combinations. In the 2006 IBC, Ev is used and not taken as zero for f exceptt for f foundation f d ti sizing. i i
•
In both codes, the redundancy factor, ρ, is specified as 1.0 for p nonstructural components.
•
In both codes, Ωo is not specified and load combinations with Ωo are not used with nonstructural components (including penthouses) 2007 Structures Congress
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Anchorage of Nonstructural Components •
In the 1997 UBC 1. Special p Requirements q for shallow anchors. Rp = 1.5 Shallow anchors defined as embed/diameter less than 8 2. Special Requirement for expansion anchors for vibration isolated equipment – 2 Fp SEAOC Bluebook only if gap > 0.25 in 3. Section 1923 – Anchorage to concrete - Strength 2.0 factor if no special inspection – 1.3 with special insp.
•
In the 2006 IBC 1. All anchor forces based on Rp of 1.5 unless: - Anchorage governed by ductile steel element or - Post installed for Seismic Applications per ACI 355.2 or - Anchors design in accordance with ACI 318-05, App. D 2. Additional 1.3 factor or maximum transferable force 3. Special requirement – vib iso equipment – 2 Fp if gap > 0.25” 4 L 4. Load d path th analysis l i to t primary i structure t t shall h ll be b performed. f d 2007 Structures Congress
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Design and Detailing Requirements of Architectural Components •
In 1997 UBC 1. Specific demands exterior walls and connections 2. UBC Standard 25-2, Part III for lay-in ceilings
•
In 2006 IBC 1. 2. 3 3. 4. 5.
Specific demands exterior walls and connections Suspending Ceilings – CISCA & ASTM standards Glazing – Drift capacity AAMA 501 501.6 6 Access Floors – special access floor details Tall Partitions – independent bracing 2007 Structures Congress
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Design and Detail Requirements for Mechanical and Electrical Equipment •
In 1997 – No specific requirements
•
In 2006 IBC 1. Sprinkler systems – NFPA 13 with amendments 2. Escalators and Elevators – ASME A17.1 3. Vessels – ASME B& PV 4. Piping – ASCE B 31.1 5. HVAC Ducting – (SMACNA not specifically referenced) 6 Lighting fixtures – Prescriptive detail requirements 6. 7. Many specific prescriptive details for Mechanical and Electrical Equipment – Section 13.6.5.5
2007 Structures Congress
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Special Certification Requirements for Certain Designated Seismic Systems (Ip=1.5) •
In 1997 UBC – No specific requirement
•
In 2006 IBC - Seismic qualification required for 1 Active mechanical and electrical equipment that are 1. required to function following a DBE 2. Components containing hazardous contents
•
Qualification to demonstrate functionality after being subject to a DBE to be determined by either: 1. Shake table testing – ICC-ES AC-156 , 2004 2. Experience Data 3. Analysis (extremely difficult for active equipment)
•
Certification required by supplier indicating compliance 2007 Structures Congress
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Final Comments about Nonstructural Components • Force levels and approaches similar between 1997 UBC and 2006 IBC. Terminology is similar. • Much more implementation detail in the 2006 IBC • Additional documentation requirements q in the 2006 IBC • Much more QA requirements in the 2006 IBC. Note there are specific requirements for supports and attachments to be shown on the construction documents documents. 2007 Structures Congress
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Nonbuilding g Structures •
Self supporting structures other than buildings that support gravity loads and resist overturning moments at their base.
•
In 1997 UBC Requirements located in: Section 1634 Nonbuilding Structures Section 1629 Criteria Selection Section 1630 Minimum Design Lateral Forces…
•
In 2006 IBC – Refers to ASCE 7-05 including Supplement 1 Chapter 15 - Seismic Design Requirements for Nonbuilding Structures Chapter 12 - Seismic Design Requirements for Building Structures Chapter p 13 - Seismic Design g Requirements q for Nonstructural Components 2007 Structures Congress
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Two Types of Nonbuilding Structures • In both 1997 UBC and 2006 IBC there are two types of nonbuilding structures 1. Those that have seismic force resisting systems that are similar to buildings (e.g. pipe racks) 2. Those that do not have seismic force resisting systems that are similar to a building (e.g. flat bottom tanks)
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Example p of a “Similar” System y
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Example of a “Not Similar” System
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Nonbuilding Structures Limits of Applicability •
1997 UBC – Wherever UBC Adopted (Western States) 1. Not required in Seismic Zone 0 but everywhere else 2. For structures similar to building – same restrictions as for b ildi structures building t t with ith similar i il systems. t 3. For structures not similar to buildings – no restrictions.
•
2006 IBC C – applies throughout the US S with ffollowing exceptions: 1. Not required for Seismic Design Category A except Sec11.7 2. For structures similar to building – same restrictions as for building structures with similar systems but with additional options. 3. For structures not similar to buildings – some restrictions 2007 Structures Congress
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Nonbuilding Structure Demands •
In both codes – same base shear equations used for building structures. Basically the same equation in the 1997 UBC and 2006 IBC except for site ground motion terminology. However, the R values, I values and minimum values are significantly different in the two codes. Also the 2006 IBC C specifies f Ωo and Cd values, detailing requirements along with height limits and restrictions for all systems while the 1997 UBC only specifies R and Ωo values values. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Equivalent Lateral Force Equations for Structures with Systems Similar to Buildings 1997 UBC
2006 IBC
( Ts = Cv / 2.5 Ca )
( Ts = SD1 / SDS )
T < Ts
V = Ca I W R
V = SDS W (R / I)
T > Ts
V = Cv I W RT
V= T > TL
SD1 W (R / I ) T
V = SD1TL W (R / I ) T2
Min V
V = 0.11 CaI W
V = 0.01 W
Min Zone 4 (S1 > 0.6)
V = 0.8 Z NV I W R
V = 0.5 S1 W (R / I )
2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Equivalent Lateral Force Equations for Structures with Systems Not Similar to Buildings 1997 UBC
2006 IBC
( Ts = Cv / 2.5 Ca )
( Ts = SD1 / SDS )
T < Ts
V = Ca I W R
V = SDS W (R / I)
T > Ts
V = Cv I W RT
V= T > TL
SD1 W (R / I ) T
V = SD1TL W (R / I ) T2
Min V
V = 0.56 CaI W
V = 0.03 W
Min Zone 4 (S1 > 0.6)
V = 1.6 Z NV I W R
V = 0.8 S1 W (or 0.5 S1 W ) (R / I ) (R / I )
2007 Structures Congress
(or 0.01 W)
Seismic Provisions of ASCE/SEI 7-05
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Comparison of Minimum Values For Structures Not Similar to Buildings •
To Compare – assume a rock site with I =1.0 1997 UBC Z = 0.4, Ca = 0.40, Nv = 1.0, Cv = 0.4 and 2006 IBC
SDS = 1.0, S1 = 0.60, SD1 = 0.40
1997 UBC V min
2006 IBC
R=2.2
R=3.6
R= 2.2*
R=3.6*
0.22 W
0.22 W
0.03 W
0.03 W
(or 0.01W)
(or 0.01W)
Zone 4 V min 0.29 W
0.17 W
0.22 W
0.13 W
(or 0.14W) (or 0.08W) *For Comparison Only 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Nonbuilding Structure Importance Factor I • B Both th the th 1997 UBC and d 2006 IBC h have assigned i d Seismic Importance Factors, I. • IIn the th 1997 UBC, UBC th the value l off I iis either ith 1 1.0 0 or 1 1.25 25 and is based on the Occupancy Category. • In the 2006 IBC IBC, the value of I is either 1 1.0, 0 1 1.25 25 or 1.5 and is based on largest value from: 1. Referenced standards for the structure type 2. Occupancy Category (Table 11.5-1) 3. Specified values in Chapter 15 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
35
Nonbuilding g Structures Similar to Buildings g R Factors and Height Limits •
In the 1997 UBC,, R,, Ωo and height g limits are the same as for building structures with 2 exceptions: 1. Concrete IMRFs permitted to height of 50 feet rather than NP in Zones 3 and 4 if R is taken as 2 2.8 8 rather than 5 5.5 5 2. Height limits may be increased by 50% if regular structures that are not occupied or accessible to general public
•
In the 2006 IBC, the R, Ωo, Cd and height limits are same as for building structures with additional options: 1. Height limits of certain systems are permitted to higher levels if lower R values are used (see next slide) 2. SCBF and special shear wall height limits can be increased by 50 % if regular structures with multiple lines of resistance – same as permitted for buildings 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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“Similar” Nonbuilding Structure Options p Ordinary Steel Concentrically Braced Frames System
Detailing
R
Height Limit (ft.) B
C
D
E
F
35
35
NP
Steel OCBFs
AISC 341
3.25
NL
NL
With Permitted Height Increase
AISC 341
2.5
NL
NL 160 160 100
With Unlimited Height
AISC 360
1.5
NL
NL
2007 Structures Congress
NL
NL NL
Seismic Provisions of ASCE/SEI 7-05
37
“Similar” Similar Nonbuilding Structure Options Intermediate Moment Frames of Steel System
Detailing
R
Height Limit (ft.) B
C
D
E
F
35
NP NP
Steel IMFs
AISC 341
4.5
NL
NL
With Permitted Height Increase
AISC 341
2.5
NL
NL 160 160 100
With Unlimited Height
AISC 341
1.5
NL
NL
2007 Structures Congress
NL
NL NL
Seismic Provisions of ASCE/SEI 7-05
38
“Similar” Similar Nonbuilding Structure Options Ordinary Moment Frames of Steel System
Detailing
R
Height Limit (ft.) B
C
D
E
F
NP NP
Steel OMFs
AISC 341
3.5
NL
NL
NP
With Permitted Height Increase
AISC 341
2.5
NL
NL
100 100 NP
With Unlimited Height
AISC 360
1.0
NL
NL
NL
2007 Structures Congress
NL NL
Seismic Provisions of ASCE/SEI 7-05
39
“Similar” Nonbuilding Structure Options p Intermediate Reinforced Concrete Moment Frames System
Detailing
R
Height Limit (ft.) B C D E F
Concrete IMFs
ACI 318 5.0 with Chptr. 21
NL
NL
NP
NP NP
With Permitted Height Increase
ACI 318 3.0 with Chptr. 21
NL
NL
50
50
With Unlimited Height
ACI 318 0.8 with Chptr. 21
NL
NL
NL
NL NL
2007 Structures Congress
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40
“Similar” Nonbuilding Structure Options p Ordinary Reinforced Concrete Moment Frames System
Detailing
R
Height Limit (ft.) B
C
D
E
F
Concrete OMFs
ACI 318 NOT with ith Ch Chptr. t 21
3.0
NL
NL
NP
NP NP
With Permitted Height Increase
ACI 318 NOT 0.8 with Chptr. 21
NL
NL
50
50
2007 Structures Congress
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41
Comparison of Selected “Not Not Similar” Similar Nonbuilding Structure R values Structure Type Skirt Supported Vessels Cast in Place Silos T k and Tanks d Pressurized P i dS Spheres h Cooling Towers Bins and Hoopers Signs and Bill Boards Amusement Structures/Monuments Trussed Towers 2007 Structures Congress
R value 1997 UBC 2006 IBC 2.9 3.6 2 2.2 2 3.6 2.9 3.6 2.2 2 2.9 9
2 or 3 3.5 2 or 3 3.5 3.0 3.5 2.0 3 3.0 0
Seismic Provisions of ASCE/SEI 7-05
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Nonstuructural Component or Nonbuilding Structure? • Sometimes its confusing whether one should use the nonbuilding structure or nonstructural component requirements. • Particularly confusing are tanks, vessels, signs and bill boards b d where h the h requirements i show h up in i 2 places. • Where Wh duplicative, d li ti if it can typically t i ll fit in i or on a building (10 feet tall or less) suggest using nonstructural requirements. requirements 2007 Structures Congress
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Load Combinations •
In both codes, strength, ASD and alternate ASD load combinations are provided.
•
In both codes codes, there are Eh and Ev loads. loads
•
In the 1997 UBC Ev may be taken as zero for the alternate ASD load combinations. In the 2006 IBC, Ev is used and not taken as zero for f exceptt for f foundation f d ti sizing. i i
•
In both codes, redundancy factor, ρ, is specified as 1.0 for “not g structures. Same as buildings g for “similar”. similar” nonbuilding
•
In both codes, Ωo is specified. However in the 1997 UBC not really explained how to use but its explained to a certain extent in the 2006 for some nonbuilding structures. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Fundamental Period Determination For Nonbuilding Structures •
In 1997 UBC – Requires that period be determined by rational methods such as Method B (Rayleigh approach).
•
In 1999 SEAOC Bluebook states Method A should not apply to both “similar” and “not similar” nonbuilding structures. Suggests Rayleigh approach or dynamic analysis analysis. BB Section C 109 109.1.4 14
•
In 2006 IBC – Fundamental Period to be determined by rational building type procedures or by the Rayleigh formula – Specifically excludes Method A type procedures to be used in determining the period of nonbuilding structures.
2007 Structures Congress
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45
Design and Detailing Requirement for Structures “Similar” to Buildings •
In 1997 UBC – No specific additional requirements provided
•
In 2006 IBC 1. Same requirements as for buildings except where noted 2. Steel Storage Racks – RMI plus additional requirements 3. Towers supporting tanks and vessels – added requirements 4. Piers and wharves – only for those accessible to the public
2007 Structures Congress
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46
Design and Detailing Requirement for Structures “Not Similar” to Buildings •
In 1997 UBC – Use approve national standards with limit that the that the total base shear overturning moment determined by them can not be less than 80 % of the UBC determined value.
•
In 2006 IBC – Some requirements provided for the following 1. Earth Retaining Structures 2. Secondary Containment Structures 3. Flat Bottom Tanks - AWWA 100, API 650, ACI 313 4. Elevated Tanks for Liquids and Granular Material 5. Boilers and Pressure Vessels – ASME BPVC 6. Liquid and Gas Spheres/ Refrigerated – ASME BPVC & API 7. Horizontal Vessels 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Final Comments About Nonbuilding Structures • Approaches between 1997 UBC and 2006 IBC similar. • Force levels, height limits and detailing requirements for structures “similar” to buildings very different between codes. • Forces levels for structures “not similar” to buildings very similar except for I factors. • More detailing requirements provided in the 2006 IBC. 2007 Structures Congress
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Chapter 14 Material Specific Requirements ((Trumped p by y IBC Chapters p 18-23)) 1. Steel: references plus light frame 2. Concrete: reference plus selected details p and section on piles 3. Composite steel and concrete: references 4 Masonry: references plus selected details 4. 5. Wood: references plus selected details 2007 Structures Congress
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Chapter 16 Response History Analysis • Provides Requirements for Selection and Scaling of Ground Motion Time Histories – virtually the same as those found in the UBC • Provides requirements for performing nonlinear response history analysis (Note: time history analysis = response history analysis)
• Similar to the UBC requirements q but with a few additional requirements.
2007 Structures Congress
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Chapters 17 - 19 • Chapter 17 – Seismic Isolation Requirements - basically the same as UBC excepts for: * ground motions * RI values and height limits • Chapter 18 – Brand new Chapter on Structures with Damping Systems – Based on NEHRP • Chapter 19 – Soil Str Structure ct re Interaction – Really Reall developed for large structures with rigid bases ((e.g. g nuclear reactor containment structures)) 2007 Structures Congress
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Chapter 20 Site Classification Procedure • Intended primarily for Geotechnical Engineers • Provides Detailed Procedures for Determining Site Class A – F • Similar Si il to t what h t is i in i the th 1997 UBC • Provides specific Details for how to deal with Site Cl F andd how Class h to t deal d l with ith refusal f l if a rockk layer is met at a depth of less than 100 feet. 2007 Structures Congress
Seismic Provisions of ASCE/SEI 7-05
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Chapter 21 Site Specific Ground Motion Procedures •
•
Specific Procedures Provided for both - Site Response Analysis - Ground Motion Hazard Analysis Limits provided on site specific determined spectra - Can be greater than map determined spectra including soil amplification lifi ti effects ff t - Can’t be less than 80% of map determined spectra including soil amplification effects. - Site Class F site specific spectra can’t be less than 80% of the map determined spectra including soil amplification effects if the site were classified Site Class E. 2007 Structures Congress
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Chapter 22 Ground Motion Maps • Maps provided for Ss and S1 on soft rock and the long period transition TL • Use for f cursory checks, h k not recommended d d ffor design • For design use the USGS web site (or CD which is coming) based on longitude and latitude of site (not zip code) determined to 3 digits beyond decimal. http://earthquake.usgs.gov/research/hazmaps/design/index.php 2007 Structures Congress
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Chapter 23 Seismic Design References • Same as Chapters 35 in IBC and UBC • Ch Chapter t 35 iin IBC T Trumps IBC if there th is i a difference. diff For F example AISC 341 is referenced in Chapter 23 while in the IBC its AISC 341-05 including Supplement No. 1. • The seismic forces specified in ASCE 7-05 are tied to the detailed reference documents. Not using the detailing specified ifi d in i the th IBC including i l di any modifications difi ti means the th specified seismic forces may not be valid.
2007 Structures Congress
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Appendix 11A Quality Assurance Provisions • Provides testing and inspection requirements for structures and nonstructural components • Not adopted typically by jurisdictions. Instead use Chapter 17 of the IBC. • Includes a description of a quality assurance plan that needs to be developed.
2007 Structures Congress
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Appendix 11B Existing Building Provisions • Provides triggering requirements for structural independent and dependent additions, alterations and change of use • Not adopted typically by jurisdictions. Instead use Chapter h 34 off the h IBC or llocally ll adopted d d ordinances.
2007 Structures Congress
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2006 IBC Modifications to ASCE 7-05 • 2006 IBC S Section ti 1613 1613.6 6P Permits it C Certain t i Less L Restrictive R t i ti Alternatives to be used than those found in ASCE 7-05 1. Assumption of flexible diaphragms – provides additional conditions when diaphragms may be considered flexible 2. Permits steel OMFs and OCBFs to be used with seismic isolation for structures assigned SDC D, E and F if RI is taken as 1.0 (currently not permitted since isolation limits tied to R table).
2007 Structures Congress
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Concluding Remarks • Seismic Provisions of ASCE 7-05 represent our best current seismic design practice • Consistency C i with i h all ll the h latest l material i l codes d – big bi improvement from the UBC • Reorganization and reformat of seismic provisions should greatly improve usability • Seismic forces in most cases will be similar or less than those h specified ifi d in i the h 1997 199 UBC C because b off the h convergence strategy that SEAOC used in developing the q 1997 UBC seismic requirements. 2007 Structures Congress
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