IBC-ASCE7QuickReference

Occupancy Category – IBC Table 1604.5

OC

Used to determine the seismic importance factor (I), Seismic Design Category (A, B, C, D, E or F) when considering the applicable spectral response acceleration parameters (S1, SDS and SD1), allowable story drift limits (Δax), Structural Observation requirements per IBC §1709, etc.

OC = I

Structures that represent a low hazard to human life in the event of failure such as agricultural facilities, certain temporary facilities, and minor storage facilities.

OC = II

Structures except those listed in Occupancy Categories I, III and IV. NOTE: This category will include the majority of buildings designed and constructed under the IBC.

OC = III

Buildings (and other structures) that represent a substantial hazard to human life in the event of failure, such as:  Covered structures whose primary occupancy is public assembly with an occupant load > 300  Elementary school, secondary school, or daycare facilities with an occupant load > 250  Colleges or adult education facilities with an occupant load > 500  Health care facilities with an occupant load ≥ 50 resident patients, but not having surgery or emergency treatment facilities  Jails and detention facilities  Any other occupancy with an occupant load > 5,000  Power generating stations, water treatment for potable water, wastewater treatment facilities, and other public utility facilities not included in Occupancy Category IV.  Buildings and other structures not included in Occupancy Category IV … containing sufficient quantities of toxic or explosive substances to be dangerous to the public if released.

OC = IV

Buildings (and other structures) designated as essential facilities, such as:  Hospitals and other health care facilities having surgery or emergency treatment facilities.  Fire, rescue, police stations and emergency vehicle garages.  Designated earthquake, hurricane or other emergency shelters.  Emergency preparedness, communication, and operation centers and other facilities required for emergency response.  Power-generating stations and other public utility facilities required as emergency backup facilities for Occupancy Category IV structures.  Structures containing highly toxic materials as defined by IBC §307, etc.  Aviation control towers, air traffic control centers and emergency aircraft hangars.  Buildings and other structures having critical national defense functions.  Water treatment facilities required to maintain water pressure for fire suppression.

Steven T. Hiner, MS, SE

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Last printed 09/27/2009

Page 1 of 13

Seismic Importance Factor – ASCE 7 – Table 11.5-1

I

Used to determine the Equivalent Lateral Force (ELF) procedure seismic response coefficient (CS), minimum & maximum diaphragm design force at each level (Fpx min. & Fpx max.), the calculated deflection of a level (δx), seismic out-of-plane force on structural walls, anchorage force of concrete or masonry structural walls, etc.

I = 1.0

Occupancy Category I and II structures.

I = 1.25

Occupancy Category III structures.

I = 1.5

Occupancy Category IV structures.

SS & S1

Mapped Maximum Considered Earthquake (MCE) Spectral Acceleration Response Parameters Used to determine the site adjusted MCE spectral acceleration response parameters SMS & SM1. Most accurately determined at this website - http://earthquake.usgs.gov/research/hazmaps/design/

SS

Mapped MCE spectral acceleration response parameter for short periods (T = 0.2 second) per IBC Figures 1613.5(1) through 1613.5(14) … use IBC Figure 1613.5(3) for California.

S1

Mapped MCE spectral acceleration response parameter for 1-second period (T = 1.0 second) per IBC Figures 1613.5(1) through 1613.5(14) … use IBC Figure 1613.5(4) for California.

Site Class – IBC Table 1613.5.2 (A, B & C) & IBC Table 1613.5.5 (D, E & F)

SC

Used to determine the site coefficients Fa & Fv. Site Class D shall be used unless the building official or geotechnical data determines that Site Class E or F soil is likely to be present at the site. Site Class D, E & F based on properties of the upper 100 feet of soil profile.

A

Hard rock (extremely rare in California … East coast only); v s > 5,000 ft/second

B

Rock; 2,500 < v s ≤ 5,000 ft/second

C

Very dense soil or soft rock; 1,200 < v s ≤ 2,500 ft/second, N > 50, s u > 2,000 psf

*D

Stiff soil profile; 600 ≤ v s ≤ 1,200 ft/second, 15 ≤ N ≤ 50, 1,000 ≤ s u ≤ 2,000 psf

E

Soft soil profile; v s < 600 ft/second, N < 15, s u < 1,000 psf … or any profile > 10 feet of soil with PI > 20, w ≥ 40%, and average su < 500 psf

F

Any profile containing soil with any of the following characteristics:  Liquefiable soils, quick and highly sensitive clays, collapsible weakly cemented soils, or  Peats and/or highly organic clays (H > 10 feet), or  Very high plasticity clays (H > 25 feet w/ PI > 75), or  Very think soft/medium stiff clays (H > 120 feet)

Steven T. Hiner, MS, SE

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Page 2 of 13

Fa & Fv Fa

Site Coefficients Used to determine the site adjusted MCE spectral acceleration response parameters SMS & SM1 Determined considering the Site Class and SS using IBC - Table 1613.5.3(1). Varies from 0.8 to 2.5. For site class F - Fa shall be determined per ASCE 7 – §11.4.7.

Fv

Determined considering the Site Class and S1 using IBC - Table 1613.5.3(2). Varies from 0.8 to 3.5. For site class F – Fv shall be determined per ASCE 7 – §11.4.7.

SMS & SM1 S MS  Fa  S S

IBC (16-37)

S M 1  Fv  S1

IBC (16-38)

SDS & SD1

Site Adjusted MCE Spectral Acceleration Response Parameters Used to determine the design spectral acceleration response parameters SDS & SD1 SMS ·g = the MCE spectral acceleration for short period structures (T = 0.2 second) adjusted for site class effects. Fa = site coefficient per IBC Table 1613.5.3(1). SM1 ·g = the MCE spectral acceleration for 1-second period structures (T = 1.0 second) adjusted for site class effects. Fv = site coefficient per IBC Table 1613.5.3(2).

Design Spectral Acceleration Response Parameters Used to determine the Seismic Design Category (SDC) when considering the Occupancy Category, seismic response coefficients (CS), seismic out-of-plane force on structural walls, the anchorage force of concrete or masonry structural walls, seismic force on nonstructural components (Fp), etc.

S DS 

2  S MS 3

IBC (16-39) SDS ·g = the 5% damped design spectral acceleration for short period structures (T = 0.2 second).

S D1 

2  SM 1 3

IBC (16-40) SD1 ·g = the 5% damped design spectral acceleration for 1-second period structures (T = 1.0 second).

Steven T. Hiner, MS, SE

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Page 3 of 13

SDC

Seismic Design Category (SDC) – IBC §1613.5.6, IBC Tables 1613.5.6(1) & 1613.5.6(2) Used to determine the permitted seismic force-resisting systems (SFRS), building height limits, permitted lateral analysis procedures, restrictions on buildings with horizontal and/or vertical irregularities, seismic detailing requirements, requirements for nonstructural components, etc.

SDC = F

Occupancy Category = IV when S1 ≥ 0.75.

SDC = E

Occupancy Category = I, II or III when S1 ≥ 0.75.

SDC = B, C or D

Use IBC Tables 1613.5.6(1) & 1613.5.6(2), Occupancy Category (I, II, III or IV) and Design Spectral Acceleration Response Parameters SDS & SD1.

SDC = A

Occupancy Category = I, II, III or IV when SDS < 0.167 & SD1 < 0.067.

SDC = A

Seismic Design Category A Structures assigned to Seismic Design Category A need only comply with the requirements of ASCE 7 – §11.7 (i.e., not ASCE 7 – Chapter 12, 13, etc.).

Structures may be assigned to Seismic Design Category A (i.e., SDC = A) under any of the following two conditions: 1. SS ≤ 0.15 and S1 ≤ 0.04 … per IBC §1613.5.1, OR 2. SDS < 0.167 and SD1 < 0.067 … per IBC Tables 1613.5.6(1) & 1613.5.6(2)

 Base Shear, V V  0.01  W

Base shear equation determined at a Strength Design force level (i.e., SD / LRFD) for structures assigned to SDC = A only.

 Vertical Distribution of Lateral Force, Fx Fx  0.01 wx

ASCE 7 (11.7-1) Determines the portion of the base shear (V) that is considered to act at the center of mass of each level x, for structures assigned to SDC = A only

 Diaphragm Design Force, Fpx F px  0.01  w px

Steven T. Hiner, MS, SE

Determines the diaphragm design force at each level x, for structures assigned to SDC = A only.

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Page 4 of 13

T

Structure Period Used to calculate the Seismic Response Coefficient (CS) in ASCE 7 (12.8-3) & (12.8-4), and to determine the permitted analytical procedures of ASCE 7 – Table 12.6-1.

 Fundamental Period, T - Building Structures The fundamental period (T) shall be established using the structural properties and deformational characteristics of the resisting elements (i.e. shear walls, braced frames, moment frames, etc.) in a properly substantiated analysis (i.e., dynamic analysis). The fundamental period (T) used shall not exceed CU times Ta. This limitation is applicable to member strengths (i.e., Strength check) but is not applicable when checking Story Drift (i.e., Serviceability check).

T  C U  Ta

CU = coefficient for upper limit on calculated period per ASCE 7 – Table 12.8-1 Alternatively, it is permitted to use the approximate building period (Ta) … in lieu of performing the analysis to determine T.

 Approximate Fundamental Period, Ta - Building Structures only Ta  Ct  hnx

ASCE 7 (12.8-7)

Approximate Fundamental Period used to estimate the fundamental period for buildings only. Not allowed to be used for nonbuilding structures. Can be used to approximate a buildings period when only the height of the structure (hn) and the structural system type are given. Determine Ct and x from ASCE 7 – Table 12.8-2.

Steel MRF’s –

Ta  0.028  (hn ) 0.8 or Ta  0.1  N

Ct = 0.028 and x = 0.8 for Steel moment-resisting frames (MRF’s) per ASCE 7 – Table 12.8-2.

ASCE 7 (12.8-8) Alternative Ta provided structure is  12 stories, story heights  10 feet, and where N = number of stories.

Concrete MRF’s –

Ta  0.016  (hn ) 0.9 or Ta  0.1  N

Steven T. Hiner, MS, SE

Ct = 0.016 and x = 0.9 for Concrete moment-resisting frames (MRF’s) per ASCE 7 – Table 12.8-2.

ASCE 7 (12.8-8) Alternative Ta provided structure is  12 stories, story heights  10 feet, and where N = number of stories.

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Page 5 of 13

T

Structure Period (continued)

 Approximate Fundamental Period, Ta - Building Structures only (continued) Steel EBF’s – Ta  0.03  (hn ) 0.75

Ct = 0.03 and x = 0.75 for Steel eccentrically braced frames (EBF’s) per ASCE 7 – Table 12.8-2.

All Others – Ta  0.02  (hn ) 0.75

Ct = 0.02 and x = 0.75 for all other structural systems including shear walls, concentrically braced frames (CBF’s), Dual Systems, etc.

Masonry or Concrete Shear Walls –

Alternative Ta for masonry or concrete shear wall structures … see ASCE 7 – §12.8.2.1

Ta 

0.0019

 hn

Cw

ASCE 7 (12.8-9)

 Fundamental Period, T - Nonbuilding Structures Use to determine the fundamental period for nonbuilding structures. This equation considers the dynamic characteristics of the nonbuilding structure (i.e., weight, stiffness, etc.).

n

T  2

 wi   i2 i 1

n

g   f i  i i 1

ASCE 7 (15.4-6)

Need to be given the weight at each level (wi), seismic force at each level (fi), and the corresponding (elastic) displacement at each level (δi) relative to the base.

 Control Period, TS - for Equivalent CS (see ASCE 7 – Figure 11.4-1) TS 

TS represents the period where the seismic response coefficient (CS) determined from ASCE 7 (12.8-2) is exactly equal to the seismic response coefficient (CS) determined from ASCE 7 (12.8-3). Helpful in determining which CS equation will govern the seismic base shear (V) when the structure period (T or Ta) is know.

S D1 S DS

 Fundamental Period, T - Single Degree of Freedom (SDOF) Structures T  2

W Kg

Steven T. Hiner, MS, SE

Use to determine the natural period of SDOF structures and SDOF nonbuilding structures. The structure period is used with a given response spectrum to determine the spectral acceleration and corresponding base shear … V = SaW/g

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Page 6 of 13

V

Seismic Base Shear – Equivalent Lateral Force (ELF) Procedure Used to calculate the total design seismic force at the base of a building or a nonbuilding structure. The base shear is used to determine the Fx forces at each level for multi-story buildings.

 Buildings and Nonbuilding Structures (where T  0.06 second) V  C S W

ASCE 7 (12.8-1) Base shear equation determined at a Strength Design force level (i.e., SD / LRFD).

 Rigid Nonbuilding Structures (where T < 0.06 second) V  0.30  S DS  W  I

CS

ASCE 7 (15.4-5) Base shear equation for rigid nonbuilding structures (i.e., T < 0.06 second) determined at a Strength Design force level (i.e., SD / LRFD).

Seismic Response Coefficient – Equivalent Lateral Force (ELF) Procedure Used to calculate the seismic base shear (V) of a building or nonbuilding structure using the Equivalent Lateral Force (ELF) Procedure.

 Buildings and Nonbuilding Structures Similar to Buildings (where T  0.06 second) use ASCE 7 – Table 12.2-1 to determine R, Ω0, and Cd for Buildings. use ASCE 7 – Table 12.2-1 or Table 15.4-1 to determine R, Ω0, and Cd for Nonbuilding structures similar to buildings.

CS 

S DS (R I )

ASCE 7 (12.8-2) Upper limit (maximum) Seismic Response Coefficient that typically governs for short period structures (e.g.,  3

CS 

S D1 T (R I )

ASCE 7 (12.8-3) Seismic Response Coefficient that typically governs for longer period structures (e.g.,  3 stories), when TS ≤ T  TL

CS 

S D1  TL T 2 (R I )

ASCE 7 (12.8-4) Seismic Response Coefficient that typically governs for very long period structures, when T > TL

C S  0.044  S DS  I ≥ 0.01 minimum CS 

stories), when T < TS

ASCE 7 (12.8-5)

Seismic Response Coefficient that may govern for long period structures, when T >> TS

0.5  S1 minimum ASCE 7 (12.8-6) Seismic Response Coefficient that may govern for long period structures, when S1 ≥ 0.6 and T >> TS (R I )

Steven T. Hiner, MS, SE

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Page 7 of 13

 Nonbuilding Structures NOT Similar to Buildings (where T  0.06 second) use ASCE 7 – Table 15.4-2 to determine R, Ω0, and Cd CS 

S DS (R I )

ASCE 7 (12.8-2) Upper limit (maximum) Seismic Response Coefficient that typically governs for short period structures (e.g.,  3

CS 

S D1 T (R I )

ASCE 7 (12.8-3) Seismic Response Coefficient that typically governs for longer period structures (e.g.,  3 stories), when TS ≤ T  TL

CS 

S D1  TL T 2 (R I )

ASCE 7 (12.8-4) Seismic Response Coefficient that typically governs for very long period structures, when T > TL

stories), when T < TS

C S  0.044  S DS  I ≥ 0.03 minimum CS 

ASCE 7 (15.4-1)

Seismic Response Coefficient that may govern for long period structures, when T >> TS

0.8  S1 Seismic Response Coefficient that may govern for long period structures, when S1 ≥ 0.6 and T >> TS minimum ASCE 7 (15.4-2) (R I ) NOTE: See ASCE 7 – §15.4.1, item 2 - exception for Tanks and Vessels.

Vertical Distribution of Seismic Forces – Equivalent Lateral Force (ELF) procedure

Fx

Used in the Equivalent Lateral Force (ELF) procedures of ASCE 7 – §12.8. Not used for the Modal Response Spectrum Analysis procedures of ASCE 7 – §12.9 or the Simplified Lateral Force Analysis procedures of ASCE 7 – §12.14. Determines the portion of the base shear (V) that is considered to act at the center of mass of each level x. This equation is intended to approximate the “dynamic” response without actually performing a dynamic analysis. When analyzing a structure, the Fx forces are used as in-plane (i.e., parallel) loads to determine the deflection at each

Fx  Cvx  V

ASCE 7 (12.8-11) level, story drifts, member forces, support reactions, the structural design of the moment frame or braced frame elements, connections, shear walls and the supporting foundations.

The Fx forces are not the forces used to directly design the floor or roof diaphragms; rather they are used to determine the diaphragm design force Fpx in ASCE 7 (12.10-1).

Cvx 

wx  hxk n

w h i 1

i

k i

Steven T. Hiner, MS, SE

ASCE 7 (12.8-12) Vertical distribution factor used to determine the vertical distribution of seismic force at each level x. For T ≤ 0.5

second, use k = 1; for T ≥ 2.5 seconds, use k = 2; for 0.5 second < T < 2.5 seconds, use k = 2 … or determine by linear interpolation between 1 and 2.

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Page 8 of 13

Fx C vx 

Vertical Distribution of Seismic Forces (continued)

wx  hx n

w i 1

C vx 

i

Vertical distribution factor for T ≤ 0.5 second.

 hi

w x  h x2 n

w i 1

i

Vertical distribution factor for T ≥ 2.5 second.

 hi2

Story Shear in the x-Story

Vx

Used to determine the seismic force to the vertical seismic force-resisting elements (i.e. shear walls, braced frames, moment frames, etc.) in the x-story with a rigid diaphragm at level x. The story shear is distributed to the vertical seismic force-resisting elements in proportion to their rigidity (or stiffness) considering accidental torsion and inherent torsion.

n

Vx   Fi

ASCE 7 (12.8-13) The Story Shear (Vx) in any story is equal to the sum of the forces Fx above that story.

ix

Diaphragm Design Force

Fpx

Used to determine the diaphragm design force at each level x. The Fpx force is applicable for the design of both flexible and rigid diaphragms to determine the diaphragm shear, chord forces, drag/collector forces, etc. The Fpx force is similar to an average of all the forces acting at and above the level under consideration.

n

Fpx 

F ix n

i

w i x

w px

ASCE 7 (12.10-1)

i

The Fpx force is often divided by the diaphragm span to determine a uniform (beam) loading on the diaphragm: ws = fpx = Fpx / L For single-story buildings, Fpx is essentially equal to the base shear (V) when wp1 is assumed to equal w1 … but check for the minimum Fpx force noted below.

F px  0.2  S DS  I  w px minimum

Minimum diaphragm design force, which may govern the diaphragm design at the lower levels of multi-story buildings or for single or two-story buildings (check when R ≥ 5).

F px  0.4  S DS  I  w px maximum

Maximum diaphragm design force, which may govern the diaphragm design at the upper levels of multi-story buildings.

Steven T. Hiner, MS, SE

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Page 9 of 13

Seismic Design Force on Nonstructural Components

Fp Fp 

Used to determine the horizontal seismic design force on nonstructural architectural components such as: out-of plane (i.e. perpendicular) loads on interior and exterior nonstructural walls and partitions, penthouses, ceilings, access floors, signs, billboards, etc.; and on mechanical and electrical components such as HVAC units, boilers, pumps, elevators, cooling towers, piping, ductwork, cable trays, etc.

ap = the component Amplification Factor per ASCE 7 – Table 13.5-1 for architectural components or ASCE 7 – 0.4a p S DSW p  z 1  2  ASCE 7 (13.3-1) Table 13.6-1 for mechanical and electrical components. R p I p   h  Rp = the component Response Modification Factor per ASCE 7 – Table 13.5-1 for architectural components or ASCE 7 – Table 13.6-1 for mechanical and electrical components.

F p  1.6 S DS I pW p max.

ASCE 7 (13.3-2) If the nonstructural component is given as attached at the roof … z / h = 1.0 NOTE: see ASCE 7 – §12.11 for requirements for the design and anchorage (for out-of-plane loads) of

 0.3S DS I pWp min.

X

ASCE 7 (13.3-3) concrete or masonry structural walls to horizontal (rigid or flexible) diaphragms.

Story Drift

 Calculated Deflection at Level x, x

x 

Cd   xe I

The calculated amplified (inelastic) deflection of Level x, at the center of mass, due to the estimated actual earthquake response.  Cd = the Deflection Amplification Factor per ASCE 7 – Table 12.2-1 ASCE 7 (12.8-15)  xe = the elastic deflection of Level x due to the strength level (i.e., SD/LRFD) seismic forces, Fx  I = the Seismic Importance Factor per ASCE 7 – Table 11.5-1

 Calculated Story Drift, x  x   x   x1

Steven T. Hiner, MS, SE

A Story is the space between levels. Story x is the space below Level x, and above Level x-1. The calculated (inelastic) Story Drift for the x-story is determined from the calculated (inelastic) deflections at the level above and below (i.e., x – x–1).

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Page 10 of 13

X

Story Drift (continued)

 Allowable Story Drift, ax Calculated Δx ≤ Allowable Δax

The calculated story drift (x) shall not exceed the allowable story drift (ax) determined from ASCE 7 – §12.12.

* Calculated  x   ax 

*MRF’s assigned to Seismic Design Category D, E or F – for seismic force-resisting systems (SFRS’s) comprised solely of moment frames … the design story drift shall not exceed the applicable allowable story drift (Δax) divided by the Redundancy Factor (ρ).

Occupancy Category I or II –  ax  0.025  hsx

Structures (other than masonry shear wall structures):  ≤ 4 stories, and  with interior walls, partitions, ceilings and exterior wall systems that have been designed to accommodate the story drifts.

Occupancy Category III –  ax  0.020  hsx Occupancy Category IV –  ax  0.015  hsx Occupancy Category I, II, III or IV –

 ax  0.010  hsx Occupancy Category I, II, III or IV –

Masonry cantilever shear wall structures … so constructed that moment transfer between shear walls (coupling) is negligible. Other masonry shear wall structures.

 ax  0.007  hsx Occupancy Category I or II –  ax  0.020  hsx Occupancy Category III –  ax  0.015  hsx

All other Structures (other than masonry shear wall structures):  > 4 stories, or  with interior walls, partitions, ceilings and exterior wall systems that have been NOT designed to accommodate the story drifts.

Occupancy Category IV –  ax  0.010  hsx

Steven T. Hiner, MS, SE

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Page 11 of 13

E

Total Seismic Load Effect Used to determine the seismic force in a structural element to be used in the load combinations of IBC §1605.2 for Strength Design (SD or LRFD) or IBC §1605.3 for Allowable Stress Design (ASD).

 Horizontal Seismic Load Effect, Eh The horizontal seismic load effect (Eh) is equal to the Redundancy Factor (ρ) times QE.

Eh    QE

QE = the effect of horizontal seismic forces due to the seismic base shear (V) or the seismic design force on nonstructural components (Fp). ASCE 7 (12.4-3) QE is due to the horizontal component of earthquake ground motion and can be an axial force in a brace; a moment, shear, or axial force in a column or beam; a moment or shear force in a shear wall … as long as the force or moment is due to V or Fp.

 Vertical Seismic Load Effect, Ev The vertical seismic load effect (Ev) due to the vertical component of earthquake ground motion.

Ev  0.2  S DS  D

ASCE 7 (12.4-4)

D = the effect of Dead Load SDS = the design spectral response acceleration parameter for short periods (T = 0.2 second) per IBC §1613.5.4 NOTE: See ASCE 7 – §12.4.2.2 - Exceptions for conditions where Ev is permitted to be taken as zero.

 Total Seismic Load Effect, E E  Eh  Ev

ASCE 7 (12.4-1) The total seismic load effect (E) to be used in SD/LRFD basic load combination IBC (16-5), ASD basic load

E  Eh  Ev

ASCE 7 (12.4-2) The total seismic load effect (E) to be used in SD/LRFD basic load combination IBC (16-7), ASD basic load

combinations IBC (16-12) & (16-13), or ASD alternative basic load combination IBC (16-20).

combination IBC (16-15), or ASD alternative basic load combination IBC (16-21).

 Redundancy Factor, ρ  = 1.0 for SDC = B & C  = 1.3 for SDC = D, E or F*

The Redundancy Factor () is used to penalize the vertical seismic force-resisting (SFR) elements for structures that are not considered to be redundant. High  = low (assumed) redundancy. The Redundancy Factor is determined separately for each principle axes of the structure and applied to all vertical SFR elements in that corresponding direction. NOTE: See ASCE 7 – §12.3.4.2 for conditions where  = 1.0 may be used for SDC = D, E or F.

Steven T. Hiner, MS, SE

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Page 12 of 13

Em

Total Seismic Load Effect including Overstrength Factor Used for conditions where consideration of structural overstrength is specifically required for elements (e.g., columns, beams, trusses, or slabs) supporting discontinuous vertical SFR elements above such as Horizontal Structural Irregularity Type 4 (ASCE 7 – Table 12.31) or Vertical Structural Irregularity Type 4 (ASCE 7 – Table 12.3-2).

 Horizontal Seismic Load Effect including Overstrength Factor, Emh The horizontal seismic load effect with overstrength (Emh) is equal to the System Overstrength Factor (Ω0) times QE.

Emh   0  QE

QE = the effect of horizontal seismic forces due to the seismic base shear (V).

ASCE 7 (12.4-7) Ω0 = the System Overstrength Factor per ASCE 7 – Table 12.2-1. NOTE: Emh need not exceed the maximum force that can be developed in the element … utilizing realistic expected values of material strengths.

 Total Seismic Load Effect including Overstrength Factor, Em Em  Emh  Ev

ASCE 7 (12.4-5) The total seismic load effect including overstrength factor (Em) to be used in the Special Seismic Load Combination

Em  Emh  Ev

ASCE 7 (12.4-6) The total seismic load effect including overstrength factor (Em) to be used in the Special Seismic Load Combination

Steven T. Hiner, MS, SE

IBC (16-22).

IBC (16-23).

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