Seismic Design Requirements, H-18-8 - Office of Construction and ...

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3.0 MODIFICATIONS TO THE REQUIREMENTS OF IBC FOR NEW CRITICAL ANDESSENTIAL FACILITIES ASSIGNED TO HIGH SEISMIC DESIGNCATEGORIES3.1 Structural Irregularities (ASCE 7, Section 12.3.3)For structures assigned to Seismic Design Categories D, E, or F, the followingtypes of irregularities as defined by ASCE 7 Table 12.3-1 & 2 are not allowed:a. Stiffness irregularity – Soft Storyb. Stiffness irregularity – Extreme Soft Storyc. Weight (mass) irregularityd. Vertical geometric irregularity3.2 Seismic-force-resisting-systems (ASCE 7, Table 12.2-1)The following structural systems are permitted for new Critical and EssentialFacilities assigned to Seismic Design Categories D, E, or F.a. Building Frame Systemsi. Steel eccentrically braced frames (EBF) moment resisting connections atcolumns away from linksii. Special reinforced concrete shear walls (Building Frame)iii. Special reinforced masonry shear walls (Building Frame)iv. Special steel concentrically braced framesv. Light frame walls with shear panels-wood structural panels/sheet steelpanels (Building Frame) for structures two stories or lessvi. Buckling-restrained braced frames, moment-resisting beam-columnconnectionsb. Moment-Resisting Frame Systems, if approved by VA.i. Special steel moment-resisting frames (SMRF)ii. Special reinforced concrete moment-resisting framesc. Dual Systemsi. Special reinforced concrete shear walls with SMRFii. Special reinforced masonry shear walls with SMRFiii. Steel EBF with SMRFiv. Special steel concentrically braced frame with SMRFv. Buckling-restrained braced frameOther structural systems as permitted by the IBC for Seismic Design Categories D,E or F, including ones that employ seismic isolation and seismic damping systemsare permitted subject to written approval by the VA.8
3.3 Special Provisions for structures assigned to Seismic Design Categories D,E, or F.The provisions of this section shall apply to all new Critical and Essential Facilities.a. Bay spacing essentially shall be equal and uniform throughout.b. Transfer beams or trusses supporting upper level columns shall not be usedunless permitted on a case by case basis by VA.c. Seismic joints shall be avoided, in so far as possible. When required, they shallbe specifically identified in the schematic design phase of the project andapproved by VA, subject to the following provisions:1. Seismic joints shall be properly detailed on the working drawings;2. Seismic joints shall be sized based on the maximum expecteddisplacements, considering the effects of story drift, diaphragmdisplacements and rotations, and a realistic approximation of elementsection properties. For materials designed considering the ultimate limitstate, such as concrete, the stiffness representative of this state shall beused. Seismic separations shall be 125% of the separation required byASCE 7; and3. Adjacent structures that are not integral with an existing structure shall beseparated by not less than 2 inches per story.3.4 Limitations on Reinforced Concrete StructuresThe provisions of this section shall apply to all new Critical and Essential Facilitiesassigned to Seismic Design Categories D, E, or F.a. Prestressed concrete structural members, including pre-tensioned and posttensionedmembers, and precast elements such as tilt-up wall panels, andprecast beam and column elements shall not be used to resist seismic forces.b. Lightweight concrete shall not be used in structural members resistingearthquake forces, except in concrete floors and roof slabs used as diaphragmelements to distribute earthquake forces to vertical lateral-load resistingelements.9
Page 2 and 3: FOREWORDBackgroundIn 1971, after th
Page 4 and 5: 1.0 DEFINITIONS1.1 ASCE/SEI 41-06:
Page 6 and 7: 2.0 GENERALThese requirements cover
Page 10 and 11: 3.5 Limitations on Steel Structures
Page 12 and 13: 5.0 SITE DATA FOR CRITICAL AND ESSE
Page 14 and 15: 6.0 COMMENTARYSection 1.0Section 1.
Page 16 and 17: [VA Facilities Occupancy Categories
Page 18 and 19: SiteTable 4 (continued)Spectral Res
Page 24: SiteTable 4 (continued)Spectral Res

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