7 2 1 / / 2 NL NL / 2211

Transcription

1 TABLE continued DESIGN COEFFICIENTS AND FACTORS FOR BASIC SEISMIC-FORCE-RESISTING SYSTEMS BASIC SEISMIC-FORCE-RESISTING SYSTEM DETAILING REFERENCE SECTION RESPONSE MODIFICATION COEFFICIENT, R a SYSTEM OVERSTRENGTH g FACTOR, Ω o DEFLECTION AMPLIFICATION b FACTOR, C d SYSTEM LIMITATIONS AND BUILDING HEIGHT LIMITATIONS (FEET) BY SEISMIC DESIGN CATEGORY C AS DETERMINED IN SECTION c AorB C D E e F e H. Ordinary plain concrete shear walls / 2 2 NL NP NP NP NP I. Composite eccentrically braced frames (14) k NL NL J. Composite concentrically braced frames (13) k / 2 NL NL K. Ordinary composite braced frames (12) k NL NL NP NP NP L. Composite steel plate shear walls (17) k 6 1 / / / 2 NL NL M. Special composite reinforced concrete shear walls with steel elements (16) k / 2 5 NL NL N. Ordinary composite reinforced concrete shear walls with steel elements (15) k / / 2 NL NL NP NP NP O. Special reinforced masonry shear walls o 5 1 / / 2 4 NL NL P. Intermediate reinforced masonry shear walls o / / 2 NL NL NP NP NP Q. Ordinary reinforced masonry shear walls o / / 4 NL 160 NP NP NP R. Detailed plain masonry shear walls o 2 1 / / / 4 NL NP NP NP NP S. Ordinary plain masonry shear walls o 1 1 / / / 4 NL NP NP NP NP T. Light frame walls with shear panels wood structural panels/sheet steel panels / / / 2 NL NL U. Light framed walls with shear panels all other materials / / / / 2 NL NL 35 NP NP V. Ordinary plain prestressed masonry shear walls / / / 4 NL NP NP NP NP W. Intermediate prestressed masonry shear walls , o / / 2 NL 35 NP NP NP X. Special prestressed masonry shear walls , o 4 1 / / 2 4 NL Moment-resisting Frame Systems A. Special steel moment frames (9) j / 2 NL NL NL NL NL B. Special steel truss moment frames (12) j / 2 NL NL NP C. Intermediate steel moment frames (10) j 4 1 / NL NL 35 h NP h,i NP h,i D. Ordinary steel moment frames (11) j 3 1 / NL NL NP h,i NP h,i NP h,i E. Special reinforced concrete moment frames (21.1) l / 2 NL NL NL NL NL (continued) 335

2 TABLE continued DESIGN COEFFICIENTS AND FACTORS FOR BASIC SEISMIC-FORCE-RESISTING SYSTEMS BASIC SEISMIC-FORCE-RESISTING SYSTEM DETAILING REFERENCE SECTION RESPONSE MODIFICATION COEFFICIENT, R a SYSTEM OVERSTRENGTH g FACTOR, Ω o DEFLECTION AMPLIFICATION b FACTOR, C d SYSTEM LIMITATIONS AND BUILDING HEIGHT LIMITATIONS (FEET) BY SEISMIC DESIGN CATEGORY AS DETERMINED IN SECTION c AorB C D E e F e F. Intermediate reinforced concrete moment frames (21.1) l / 2 NL NL NP NP NP G. Ordinary reinforced concrete moment frames (21.1) l / 2 NL NP NP NP NP H. Special composite moment frames (9) k / 2 NL NL NL NL NL I. Intermediate composite moment frames (10) k / 2 NL NL NP NP NP J. Composite partially restrained moment frames (8) k / NP NP K. Ordinary composite moment frames (11) k / 2 NL NP NP NP NP L. Masonry wall frames / NL NL Dual Systems with Special Moment Frames A. Steel eccentrically braced frames, momentresisting connections, at columns away from links (15) j / 2 4 NL NL NL NL NL B. Steel eccentrically braced frames, nonmomentresisting connections, at columns away from links (15) j / 2 4 NL NL NL NL NL C. Special steel concentrically braced frames (13) j / / 2 NL NL NL NL NL D. Special reinforced concrete shear walls / / 2 NL NL NL NL NL E. Ordinary reinforced concrete shear walls / 2 6 NL NL NP NP NP F. Composite eccentrically braced frames (14) k / 2 4 NL NL NL NL NL G. Composite concentrically braced frames (13) k / 2 5 NL NL NL NL NL H. Composite steel plate shear walls (17) k / / 2 NL NL NL NL NL I. Special composite reinforced concrete shear walls with steel elements (16) k / / 2 NL NL NL NL NL J. Ordinary composite reinforced concrete shear walls with steel elements (15) k / 2 6 NL NL NP NP NP K. Special reinforced masonry shear walls o / 2 NL NL NL NL NL L. Intermediate reinforced masonry shear walls o 6 1 / / 2 NL NL NP NP NP 5. Dual Systems with Intermediate Moment Frames m NL 35 h NP h,i NP A. Special steel concentrically braced frames f (13) j 4 1 / / 2 4 NL B. Special reinforced concrete shear walls / 2 5 NL NL C. Ordinary reinforced concrete shear walls / / / 2 NL NL NP NP NP (continued) 336

3 TABLE continued DESIGN COEFFICIENTS AND FACTORS FOR BASIC SEISMIC-FORCE-RESISTING SYSTEMS BASIC SEISMIC-FORCE-RESISTING SYSTEM DETAILING REFERENCE SECTION RESPONSE MODIFICATION COEFFICIENT, R a SYSTEM OVERSTRENGTH g FACTOR, Ω o DEFLECTION AMPLIFICATION b FACTOR, C d SYSTEM LIMITATIONS AND BUILDING HEIGHT LIMITATIONS (FEET) BY SEISMIC DESIGN CATEGORY AS DETERMINED IN SECTION c AorB C D d E e F e D. Ordinary reinforced masonry shear walls o / 2 NL 160 NP NP NP E. Intermediate reinforced masonry shear walls o / 2 NL NL NP NP NP F. Composite concentrically braced frames (13) k / / 2 NL NL NP G. Ordinary composite braced frames (12) k / 2 3 NL NL NP NP NP H. Ordinary composite reinforced concrete shear walls with steel elements (15) k 5 1 / / / 2 NL NL NP NP NP 6. Shear Wall-frame Interactive System with Ordinary Reinforced Concrete Moment Frames and Ordinary Reinforced Concrete Shear Walls 21.1 l / / 2 5 NL NP NP NP NP 7. Inverted Pendulum Systems A. Cantilevered column systems 2 1 / / 2 NL NL B. Special steel moment frames (9) j 2 1 / / 2 NL NL NL NL NL C. Ordinary steel moment frames (11) j 1 1 / / 2 NL NL NP NP NP D. Special reinforced concrete moment frames 21.1 l 2 1 / / 4 NL NL NL NL NL 8. Structural Steel Systems Not Specifically Detailed for Seismic Resistance AISC 335 AISC LRFD AISI AISC HSS NL NL NP NP NP For SI: 1 foot = mm, 1 pound per square foot = KN/m 2. a. Response modification coefficient, R, for use throughout. b. Deflection amplification factor, C d. c. NL = Not limited and NP = Not permitted. d. See Section for a description of building systems limited to buildings with a height of 240 feet or less. e. See Section for building systems limited to buildings with a height of 160 feet or less. f. Ordinary moment frame is permitted to be used in lieu of intermediate moment frame in Seismic Design Categories B and C. g. The tabulated value of the overstrength factor, Ω o, is permitted to be reduced by subtracting 1 / 2 for structures with flexible diaphragms but shall not be taken as less than 2.0 for any structure. h. Steel ordinary moment frames and intermediate moment frames are permitted in single-story buildings up to a height of 60 feet, when the moment joints of field connections are constructed of bolted end plates and the dead load of the roof does not exceed 15 pounds per square foot. The dead weight of the portion of walls more than 35 feet above the base shall not exceed 15 pounds per square foot. i. Steel ordinary moment frames are permitted in buildings up to a height of 35 feet, where the dead load of the walls, floors and roof does not exceed 15 pounds per square foot. j. AISC 341 Part I or Part III section number. k. AISC 341 Part II section number. l. ACI 318, Section number. m.steel intermediate moment resisting frames as part of a dual system are not permitted in Seismic Design Categories D, E, and F. n. Steel ordinary concentrically braced frames are permitted in penthouse structures and in single-story buildings up to a height of 60 feet when the dead load of the roof does not exceed 15 pounds per square foot. o. ACI 530/ASCE 5/TMS 402 section number. 337

4 Limited building height. For buildings that have steel-braced frames or con crete cast-in-place shear walls, the height limits in Table for Seismic Design Category D or E are in creased to 240 feet ( mm) and for Seis mic De sign Category F to 160 feet ( mm) pro vided that the buildings are configured such that the braced frames or shear walls arranged in any one plane con form to the following: 1. The braced frames or shear walls in any one plane shall re sist no more than 50 per cent of the to tal seismic forces in each direction, neglecting tor sional effects. 2. The seis mic force in the braced frames or shear walls in any one plane re sult ing from torsional effects shall not exceed 20 per cent of the total seismic force in the braced frames or shear walls In ter ac tion ef fects. Moment-resisting frames that are en closed or adjoined by stiffer elements not con sid ered to be part of the seismic-force-re sist ing system shall be de signed so that the ac tion or failure of those elements will not impair the ver ti cal load and seismic-force-resisting capability of the frame. The de sign shall con sider and provide for the effect of these rigid elements on the structural sys tem at deformations corresponding to the design story drift, D, as de ter mined in Sec tion In ad di tion, the ef fects of these elements shall be considered when determining whether a struc ture has one or more of the ir reg u lar i ties defined in Sec tion Deformational com pat i bil ity. Ev ery struc tural com po nent not in cluded in the seismic-force-re sist ing sys tem in the di rec tion un der consid er ation shall be de signed to be ad e quate for vertical load-car ry ing capacity and the induced mo ments and shears resulting from the de sign story drift, D, as de ter mined in accordance with Section Where allowable stress design is used, D shall be com puted with out dividing the earthquake force by 1.4. The moments and shears in duced in components that are not included in the seismic-force-resisting system in the di rec tion under consideration shall be cal cu lated in cluding the stiff en ing effects of adjoining rigid struc tural and nonstructural el e ments. Exception: Re in forced concrete frame mem bers not designed as part of the seismic-force-resisting sys tem shall comply with Sec tion of ACI Special moment frames. A special mo ment frame that is used but not re quired by Table is permitted to be discontinued and supported by a stiffer sys tem with a lower response modification coefficient, R, provided the requirements of Sections and are met. Where a special mo ment frame is re quired by Ta ble , the frame shall be continuous to the foundation. SECTION 1618 DYNAMIC ANALYSIS PROCEDURE FOR THE SEISMIC DESIGN OF BUILDINGS Dynamic anal y sis pro ce dures. The fol low ing dynamic anal y sis procedures are permitted to be used in lieu of the equivalent lateral force procedure of Sec tion : 1. Modal Re sponse Spectral Anal y sis. 2. Lin ear Time-his tory Analysis. 3. Non lin ear Time-history Analysis. The dynamic anal y sis procedures listed above shall be per formed in accor dance with the require ments of Sections 9.5.6, and 9.5.8, respectively, of ASCE 7. SECTION 1619 EARTHQUAKE LOADS SOIL-STRUCTURE INTERACTION EFFECTS Anal y sis procedure. If soil-structure inter ac tion is con sid ered in the deter mi na tion of seismic design forces and cor re spond ing displacements in the struc ture, the procedure given in Section of ASCE 7 shall be used. SECTION 1620 EARTHQUAKE LOADS DESIGN, DETAILING REQUIREMENTS AND STRUCTURAL COMPONENT LOAD EFFECTS Struc tural component design and detailing. The design and detail ing of the com po nents of the seismic-force-resist ing sys tem shall com ply with the requirements of Sec tion of ASCE 7 in addi tion to the nonseismic require ments of this code except as modified in Sections , and Ex cep tion: For struc tures de signed us ing the simplified analysis pro ce dure in Section , the provisions of Sections through shall be used ASCE 7, Sec tion Section of ASCE 7 shall not ap ply ASCE 7, Sec tion Modify ASCE 7, Section , to read as follows: Elements sup port ing dis con tin u ous walls or frames. Col umns, beams, trusses or slabs supporting discon tin u ous walls or frames of struc tures and the con nec tions of the discontinuous el e ment to the sup port ing mem ber having plan irregularity Type 4 of Table or ver ti cal ir regularity Type 4 of Table shall have the design strength to re sist the maximum axial force that can develop in accordance with the spe cial seis mic loads of Section Exceptions: 1. The quantity E in Section need not exceed the max i mum force that can be trans mit ted to the element by the lateral-force-resisting sys tem at yield. 2. Con crete slabs sup port ing light-framed walls. 338

5 ASCE 7, Sec tion Modify ASCE 7, Sec tion , to read as follows: Seismic De sign Category C. Struc tures assigned to Category C shall conform to the requirements of Section for Category B and to the requirements of this sec tion. Structures that have plan structural irregularity Type 1a or 1b of Table along both principal plan axes, or plan struc tural irregularity Type 5 of Table , shall be an a lyzed for seismic forces in com pli ance with Section When the square root of the sum of the squares method of combining di rectional effects is used, each term com puted shall be assigned the sign that will yield the most conservative result. The orthogonal combination procedure of Sec tion , Item a, shall be re quired for any col umn or wall that forms part of two or more in ter sect ing seismic-force-re sist ing systems and is subjected to ax ial load due to seis mic forces act ing along either principal plan axis equal ing or ex ceed ing 20 percent of the ax ial load de sign strength of the col umn or wall Struc tural com po nent design and detailing (for use in the simplified analysis procedure of Section ). The design and detail ing of the com po nents of the seismic-force-resist ing system for structures designed using the simplified anal y sis pro ce dure in Section shall com ply with the require ments of this sec tion in addi tion to the nonseismic requirements of this code. Buildidngs shall not exceed the limitations of Section Exception: Struc tures assigned to Seis mic De sign Category A. Struc tures assigned to Seismic Design Category B (see Sec tion 1616) shall con form to Sec tions through Second-order load ef fects. Where q exceeds 0.10 as determined in Section in ASCE 7, second-order load ef fects shall be included in the evaluation of com po nent and con nec tion strengths Open ings. Where openings occur in shear walls, di a phragms or other plate-type elements, re in force ment at the edges of the openings shall be designed to transfer the stresses into the structure. The edge re in force ment shall ex tend into the body of the wall or di a phragm a dis tance sufficient to develop the force in the reinforcement Discontinuities in vertical system. Struc tures with a dis con ti nu ity in lat eral capacity, vertical irregularity Type 5, as defined in Table , shall not be over two sto ries or 30 feet (9144 mm) in height where the weak story has a calculated strength of less than 65 per cent of the story above. Exception: Where the weak story is ca pa ble of resisting a total seismic force equal to the overstrength factor, W 0, as given in Table , multiplied by the design force prescribed in Sec tion , the height limitation does not ap ply Connections. All parts of the structure, except at separation joints, shall be in ter con nected and the con nec tions shall be designed to re sist the seismic force, F p, induced by the parts be ing con nected. Any smaller por tion of the struc ture shall be tied to the remainder of the struc ture for the greater of: F p = S DS w p (Equation 16-58) or F p = 0.05 w p (Equation 16-59) where: S DS = The de sign, 5-percent damped, spectral re sponse accel er a tion at short pe ri ods as defined in Section w p = The weight of the smaller por tion. A positive connection for resisting a hor i zon tal force acting par al lel to the mem ber shall be pro vided for each beam, girder or truss to its support for a force not less than 5 per cent of the dead plus live load reaction Diaphragms. Per mis si ble de flec tion shall be that de flec tion up to which the diaphragm and any at tached dis tributing or re sist ing el e ment will main tain its struc tural in tegrity under de sign load con di tions, such that the re sist ing el e ment will continue to support de sign loads without dan ger to oc cu pants of the struc ture. Floor and roof diaphragms shall be de signed to re sist F p as follows: F p = 0.2 I E S DS w p + V px (Equation 16-60) where: F p = The seis mic force in duced by the parts. I E = Oc cu pancy im por tance factor (Table ). S DS = The short-pe riod site de sign spectral re sponse accel eration coefficient (Sec tion 1615). w p = The weight of the diaphragm and other elements of the struc ture at tached to the di a phragm. V px = The por tion of the seis mic shear force at the level of the di a phragm, re quired to be trans ferred to the com po nents of the ver ti cal seismic-force-resisting sys tem because of the offsets or changes in stiffness of the vertical components above or below the diaphragm. Diaphragms shall provide for both shear and bending stresses re sult ing from these forces. Di a phragms shall have ties or struts to distribute the wall anchorage forces into the di a phragm. Diaphragm con nec tions shall be positive, me chan i cal or welded-type connections Collector elements. Collector elements shall be pro vided that are ca pa ble of trans fer ring the seismic forces orig i nat ing in other por tions of the structure to the element providing the re sis tance to those forces. Col lec tor el e ments, splices and their con nec tions to re sist ing elements shall have the design strength to re sist the special load com bi nations of Section Exception: In structures or portions thereof braced en tirely by light-framed shear walls, collector elements, splices and con nec tions to re sist ing elements need only 339

6 have the strength to re sist the load combinations of Section or Bear ing walls and shear walls. Bearing walls and shear walls and their an chor age shall be de signed for an out-of-plane force, F p, that is the greater of 10 percent of the weight of the wall, or the quan tity given by Equation 16-61: F p = 0.40 I E S DS w w (Equation 16-61) where: I E = Occupancy im por tance factor (Table ). S DS = The short-pe riod site de sign spectral re sponse acceleration coefficient (Sec tion or ). w w = The weight of the wall. In ad di tion, con crete and ma sonry walls shall be anchored to the roof and floors and mem bers that pro vide lat eral sup port for the wall or that are supported by the wall. The an chor age shall provide a direct connection be tween the wall and the sup port ing con struc tion ca pa ble of re sist ing the greater of the force, F p, as given by Equation or (400 S DS I E ) pounds per lin ear foot of wall. For SI: 5838 S DS I E N/m. Walls shall be de signed to resist bending be tween an chors where the anchor spac ing ex ceeds 4 feet (1219 mm). Parapets shall con form to the re quire ments of Section of ASCE Inverted pendulum-type struc tures. Supporting columns or piers of inverted pendulum-type structures shall be de signed for the bending moment calculated at the base de ter mined us ing the procedures given in Section and varying uniformly to a moment at the top equal to one-half the cal cu lated bend ing mo ment at the base Elements sup port ing discontinuous walls or frames. Col umns or other el e ments subject to vertical reactions from dis con tin u ous walls or frames of structures hav ing plan irregularity Type 4 of Ta ble or vertical irregularity Type 4 of Table shall have the design strength to re sist spe cial seis mic load combinations of Sec tion The connections from the discontinuous walls or frames to the sup port ing elements need not have the de sign strength to resist the spe cial seis mic load combinations of Sec tion Ex cep tions: 1. The quan tity, E m, in Section need not exceed the max i mum force that can be transmitted to the el e ment by the lateral-force-resisting system at yield. 2. Con crete slabs sup port ing light-framed walls Direction of seis mic load. The di rec tion of ap pli ca tion of seismic forces used in de sign shall be that which will pro duce the most critical load ef fect in each component. The re quire ment will be deemed satisfied if the design seis mic forces are applied sep a rately and independently in each of the two or thogo nal di rec tions Seismic Design Cat e gory C. Structures assigned to Seis mic Design Category C (see Sec tion 1616) shall conform to the requirements of Section for Seis mic Design Category B and to Sections through Anchorage of concrete or masonry walls. Concrete or masonry walls shall be an chored to floors and roofs and members that pro vide out-of-plane lat eral sup port for the wall or that are sup ported by the wall. The an chor age shall pro vide a positive direct con nec tion between the wall and floor or roof ca pa ble of re sist ing the hor i zon tal forces spec i fied in Equation for struc tures with flex i ble diaphragms or in Section of ASCE 7 (us ing a p of 1.0 and R p of 2.5) for structures with diaphragms that are not flexible. F p = 0.8 S DS I E w w (Equation 16-62) where: F p = The de sign force in the individual an chors. I E = Occupancy im por tance factor in ac cor dance with Section S DS = The de sign earthquake spec tral re sponse ac cel er a tion at short period in ac cor dance with Section w w = The weight of the wall trib u tary to the anchor. Diaphragms shall be pro vided with con tin u ous ties or struts between diaphragm chords to distribute these anchorage forces into the di a phragms. Where added chords are used to form subdiaphragms, such chords shall trans mit the an chor age forces to the main cross ties. The maximum length-to-width ratio of the structural subdiaphragm shall be 2 1 / 2 to 1. Connections and anchorages ca pa ble of resisting the prescribed forces shall be pro vided between the diaphragm and the at tached components. Con nec tions shall extend into the di a phragms a sufficient distance to develop the force trans ferred into the di a phragm. The strength design forces for steel el e ments of the wall an chor age sys tem shall be 1.4 times the force oth er wise re quired by this section. In wood di a phragms, the con tin u ous ties shall be in addition to the di a phragm sheath ing. Anchorage shall not be accom plished by use of toenails or nails subject to withdrawal, nor shall wood ledgers or framing be used in cross-grain bending or cross-grain ten sion. The diaphragm sheathing shall not be con sid ered effective as providing the ties or struts re quired by this section. In metal deck di a phragms, the metal deck shall not be used as the continuous ties re quired by this sec tion in the direction perpendicular to the deck span. Diaphragm-to-wall anchorage using em bed ded straps shall be at tached to or hooked around the re in forc ing steel or other wise terminated so as to di rectly transfer force to the reinforc ing steel Direction of seismic load. For struc tures that have plan structural irregularity Type 1a or 1b of Table along both principal plan axes, or plan struc tural irregularity Type 5 in Ta ble , the crit i cal di rec tion requirement of Section shall be deemed satisfied if com ponents and their foun da tions are de signed for the following or thogo nal com bi na tion of pre scribed loads. One hundred per cent of the forces for one direction plus 30 per cent of the forces for the perpendicular direction. The

7 com bi na tion requiring the maximum com po nent strength shall be used. Al ter na tively, the effects of the two or thogonal directions are per mit ted to be com bined on a square root of the sum of the squares (SRSS) ba sis. When the SRSS method of combining directional effects is used, each term computed shall be as signed the sign that will re sult in the most con ser va tive result. The orthogonal combination procedure above shall be required for any column or wall that forms part of two or more in ter sect ing seismic-force-resisting sys tems and is subjected to axial load due to seismic forces act ing along either principal plan axis equal ing or ex ceed ing 20 per cent of the ax ial load design strength of the column or wall Seismic Design Cat e gory D. Structures assigned to Seis mic Design Category D shall con form to the require ments of Section for Seismic Design Category C and to Sec tions through Plan or vertical irregularities. For build ings having a plan struc tural irregularity of Type 1a, 1b, 2, 3 or 4 in Table or a ver ti cal structural irregularity of Type 4 in Table , the de sign forces determined from Section shall be increased 25 percent for con nections of di a phragms to vertical elements and to collectors, and for con nec tions of collectors to the vertical el e ments. Exception: When connection de sign forces are determined us ing the special seismic load combinations of Section Ver ti cal seismic forces. In ad di tion to the applicable load combinations of Section 1605, hor i zon tal cantilever and hor i zon tal pre stressed components shall be designed to resist a minimum net upward force of 0.2 times the dead load Diaphragms. Floor and roof diaphragms shall be designed to resist design seismic forces determined in accor dance with Equation as fol lows: n F i F px = i= x n w px (Equa tion 16-63) w i i=x where: F i = The de sign force applied to Level i. F px = The di a phragm de sign force. w i = The weight trib u tary to Level i. = The weight trib u tary to the diaphragm at Level x. w px The force determined from Equation need not ex ceed 0.4S DS I E w px but shall not be less than 0.2S DS I E w px where S DS is the de sign spec tral re sponse ac cel er a tion at short pe riod determined in Sec tion and I E is the occupancy im por tance factor determined in Section When the diaphragm is re quired to trans fer design seismic force from the ver ti cal-re sist ing el e ments above the diaphragm to other vertical-resisting elements below the diaphragm due to off sets in the place ment of the elements or to changes in rela tive lat eral stiff ness in the ver ti cal el e ments, these forces shall be added to those determined from Equa tion and to the upper and lower limits on that equation Collector elements. Collector elements shall be pro vided that are ca pa ble of trans fer ring the seismic forces orig i nat ing in other por tions of the structure to the element providing resistance to those forces. Collector el e ments, splices and their con nec tions to resist ing elements shall resist the forces determined in accordance with Equation In ad di tion, col lec tor el e ments, splices and their con nec tions to re sist ing elements shall have the design strength to resist the earthquake loads as defined in the spe cial load com bi na tions of Sec tion Exception: In structures, or portions thereof, braced en tirely by light-framed shear walls, collector elements, splices and their connections to re sist ing elements need only be de signed to resist forces in ac cor dance with Equa tion Build ing sep a ra tions. All structures shall be sepa rated from adjoining struc tures. Sep a ra tions shall allow for the dis place ment δ M. Adjacent build ings on the same prop erty shall be separated by at least δ MT where δ MT = (δ M1 ) 2 +(δ M 2 ) 2 (Equation 16-64) and δ M1 and δ M2 are the displacements of the adjacent build ings. When a struc ture ad joins a property line not com mon to a public way, that struc ture shall also be set back from the property line by at least the dis place ment, δ M, of that structure. Exception: Smaller sep a ra tions or prop erty line setbacks shall be permitted when justified by ra tio nal anal y ses based on maximum ex pected ground mo tions An chor age of concrete or masonry walls to flexi ble di a phragms. In ad di tion to the requirements of Sec tion , con crete and ma sonry walls shall be anchored to flexible diaphragms based on the following: 1. When elements of the wall an chor age system are not loaded concentrically or are not per pen dic u lar to the wall, the system shall be de signed to re sist all components of the forces induced by the eccentricity. 2. When pi las ters are pres ent in the wall, the anchorage force at the pi las ters shall be cal cu lated con sid er ing the ad di tional load trans ferred from the wall panels to the pi las ters. The min i mum an chor age at a floor or roof shall not be less than that specified in Item Seis mic Design Category E or F. Structures assigned to Seis mic Design Category E or F (Section 1616) shall con form to the require ments of Sec tion for Seis mic Design Category D and to Sec tion Plan or ver ti cal irregularities. Structures having plan irregularity Type 1b of Ta ble or ver ti cal ir reg u lar i ties Type 1b or 5 of Ta ble shall not be per mit ted. 341

8 SECTION 1621 ARCHITECTURAL, MECHANICAL AND ELECTRICAL COMPONENT SEISMIC DESIGN REQUIREMENTS Component design. Architectural, mechanical, electrical and nonstructural systems, components and elements permanently attached to structures, including supporting structures and attachments (hereinafter referred to as components ), and nonbuilding structures that are supported by other structures, shall meet the requirements of Section 9.6 of ASCE 7 except as modified in Sections , and , excluding Section , of ASCE 7, as amended in this section ASCE 7, Section : Section of ASCE 7 shall not apply ASCE 7, Section Modify ASCE 7, Section , to read as follows: General. Partitions that are tied to the ceiling and all partitions greater than 6 feet (1829 mm) in height shall be laterally braced to the building structure. Such bracing shall be independent of any ceiling splay bracing. Bracing shall be spaced to limit horizontal deflection at the partition head to be compatible with ceiling deflection requirements as determined in Section for suspended ceilings and Section for other systems. Exception: Partitions not taller than 9 feet (2743 mm) when the horizontal seismic load does not exceed 5 psf (0.240 KN/m 2 ) required in Section of the International Building Code ASCE 7, Section Modify ASCE 7, Section , to read as follows: Mechanical equipment, attachments and supports. Attachments and supports for mechanical equipment not covered in Sections through or Section shall be designed to meet the force and displacement provisions of Section and and the additional provisions of this section. In addition to their attachments and supports, such mechanical equipment designated as having an I p = 1.5, which contains hazardous or flammable materials in quantities that exceed the maximum allowable quantities for an open system listed in Section 307 of the International Building Code, shall, itself, be designed to meet the force and displacement provisions of Sections and and the additional provisions of this section. The seismic design of mechanical equipment, attachments and their supports shall include analysis of the following: the dynamic effects of the equipment, its contents and, when appropriate, its supports. The interaction between the equipment and the supporting structures, including other mechanical and electrical equipment, shall also be considered. SECTION 1622 NONBUILDING STRUCTURES SEISMIC DESIGN REQUIREMENTS Nonbuilding structures. The requirements of Section 9.14 of ASCE 7 shall apply to nonbuilding structures except as modified by Sections , and ASCE 7, Section Modify Section , Item 9, to read as follows: 9.Where an approved national standard provides a basis for the earthquake-resistant design of a particular type of nonbuilding structure covered by Section 9.14, such a standard shall not be used unless the following limitations are met: 1. The seismic force shall not be taken as less than 80 percent of that given by the remainder of Section The seismic ground acceleration, and seismic coefficient, shall be in conformance with the requirements of Sections and , respectively. 3. The values for total lateral force and total base overturning moment used in design shall not be less than 80 percent of the base shear value and overturning moment, each adjusted for the effects of soil structure interaction that is obtained by using this standard ASCE 7, Section Modify Section to read as follows: General. This section applies to all earth-retaining walls. The applied seismic forces shall be determined in accordance with Section with a geotechnical analysis prepared by a registered design professional. The seismic use group shall be determined by the proximity of the retaining wall to other nonbuilding structures or buildings. If failure of the retaining wall would affect an adjacent structure, the seismic use group shall not be less than that of the adjacent structure, as determined in Section Earth-retaining walls are permitted to be designed for seismic loads as either yielding or nonyielding walls. Cantilevered reinforced concrete retaining walls shall be assumed to be yielding walls and shall be designed as simple flexural wall elements ASCE 7, Section Add a new Section to read as follows: Buried structures. As used in this section, the term buried structures means subgrade structures such as tanks, tunnels and pipes. Buried structures that are designated as Seismic Use Group II or III, as determined in Section 9.1.3, or are of such a size or length as to warrant special seismic design as determined by the registered design professional, shall be identified in the geotechnical report. Buried structures shall be designed to resist seismic lateral forces determined from a substantiated analysis using standards approved by the building official. Flexible couplings shall be provided for buried structures where changes in the support system, configurations or soil condition occur.

9 á SECTION 1623 SEISMICALLY ISOLATED STRUCTURES Design requirements. Every seismically isolated structure and every portion thereof shall be designed and constructed in accordance with the requirements of Section 9.13 of ASCE 7, except as modified in Section ASCE 7, Section Modify ASCE 7, Section , to read as follows: Fire resistance. Fire-resistance ratings for the isolation system shall comply with Section of the International Building Code. 343

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