1、Section 5 DESIGN REQUIREMENTS FOR BRIDGES IN SEISMIC PERFORMANCE CATEGORY A 5.1 GENERAL or, Bridges classified as SPC A in accordance with Table 3.4 of Article 3.4 shall conform to all the requirements of this Section. 5.2 DESIGN FORCES FOR SEISMIC PERFORMANCE CATEGORY A If a mechanical device is us
2、ed to connect the super- structure to the substructure it shall be designed to resist a horizontal seismic force in each restrained direction equal to 0.20 times the tributary weight. For each segment of a superstructure, the tributary weight at the line of fixed bearings, used to determine the long
3、itudinal connection design force, is defined as the total weight of the segment. If each bearing supporting a segment or simply sup- ported span is restrained in the transverse direction, the tributary weight used to determine the transverse connec- tion design force is defined as the dead load reac
4、tion at that bearing. 5.3 DESIGN DISPLACEMENTS FOR SEISMIC PERFORMANCE CATEGORY A Minimum bearing support lengths as determined in this article shall be provided for the expansion ends of all girders. Bridges classified as SPC A shall meet the following requirement: Bearing seats supporting the expa
5、nsion ends of girders, as shown in Figure 3.10, shall be designed to provide a minimum support length N (in. or mm), mea- sured normal to the face of an abutment or pier, not less than that specified below. N = (8 + 0.02L + 0.08H) (1 + 0.000125S2) (in) (5-1A) N= (203 + 1.67L + 6.66H) (1 + 0.000125S2
6、) (mm) (5-1B) where, L = length, in feet for Equation (5-1A) or meters for Equation (5-1B), of the bridge deck to the adja- cent expansion joint, or to the end of the bridge deck. For hinges within a span, L shall be the sum of LI and L2, the distances to either side of the hinge. For single span br
7、idges L equals the length of the bridge deck. These lengths are shown in Figure 3.10. S = angle of skew of support in degrees, measured from a line normal to the span. and H is given by one of the following: for abutments, H is the average height, in feet for Equation (5-1A) or meters for Equation (
8、5-1B), of columns supporting the bridge deck to the next ex- pansion joint. H = O for single span bridges. for columns and/or piers, H is the column or pier height in feet for Equation (5-1A) or meters for Equation (5-1B). for hinges within a span, H is the average height of the adjacent two columns
9、 or piers in feet for Equation (5-1A) or meters for Equation (5-1B). 5.4 FOUNDATION AND ABUTMENT DESIGN REQUIREMENTS FOR SEISMIC PERFORMANCE CATEGORY A There are no special seismic design requirements for the foundations and abutments of bridges in this category. Nevertheless, compliance is assumed
10、with all require- ments that are necessary to provide support for vertical 457 45 8 HIGHWAY BRIDGES 5.4 and lateral loads other than those due to earthquake mo- tions. These include, but are not limited to, provisions for the extent of foundation investigation, fills, slope stabil- ity, bearing and
11、lateral soil pressures, drainage, settlement control, and pile requirements and capacities. 5.5 STRUCTURAL STEEL DESIGN REQUIREMENTS FOR SEISMIC PERFORMANCE CATEGORY A No consideration of seismic forces is required for the design of structural components for bridges in this cate- gory except for the
12、 design of the connection of the super- structure to the substructure as specified in Article 5.2. Nevertheless, design and construction of structural steel columns and connections shall conform to the re- quirements of Division I. Either Service Load or Load Factor design may be used. If Service Lo
13、ad design is used the allowable stresses are permitted to increase by 50%. 5.6 REINFORCED CONCRETE DESIGN REQUIREMENTS FOR SEISMIC PEWORMANCE CATEGORY A No consideration of seismic forces is required for the design of structural components for bridges in this category except for the design of the co
14、nnection of the superstructure to the substructure as specified in Ar- ticle 5.2. Nevertheless, design and construction of cast-in-place monolithic reinforced concrete columns, pier footings and connections shall conform to the requirements of Division I. Either Service Load or Load Factor design may be used. If Service Load design is used the allowable stresses are permitted to increase by 33%.
