罕遇地震下少筋混凝土桥墩最低配筋率研究

Study of Minimum Reinforcement Ratios for Concrete Piers Arranged with Small Amount of Reinforcement Under Rare Earthquake

为了研究少筋混凝土桥墩在罕遇地震下的抗震性能,给少筋混凝土桥墩的配筋率设计提供理论依据,以高速铁路32m简支梁桥为研究对象,通过拟静力试验得到了少筋混凝土桥墩的抗震验算指标,基于有限延性抗震设计思想提出了相应的验算方法,并分析了3种场地条件、2种墩高下的桥墩抗震性能。结果表明:在场地较好的条件下,配筋率小于0.5%的中、低墩,在强震作用下可达到"大震不倒"的抗震性能要求;地震动峰值加速度为0.1g、0.21g、0.32g、0.38g、0.57g时,少筋混凝土中、低墩的最低配筋率分别为0.1%、0.2%、0.3%、0.4%、0.5%;场地条件对桥墩地震反应的影响显著,场地条件较差时,应提高桥墩的配筋率,并加强结构的抗震措施。

To study the seismic performance of the concrete piers arranged with a small amount of reinforcement under the rare earthquake and to provide the theoretic basis for the design of rein‐forcement ratios for the piers ,a 32‐m span simply‐supported beam bridge on the high‐speed rail‐way was taken as the study object and the seismic checking indexes of the piers were obtained though the pseudo static tests .Based on the seismic design idea of the limited ductility ,the corre‐sponding checking calculation method was proposed and the seismic performance of the piers under the 3 kinds of the filed conditions and 2 kinds of the pier height was analyzed .The results of the a‐nalysis reveal that under the fine field condition ,the low and medium height piers with reinforce‐ment ratios being less than 0 .5% can meet the seismic resistance requirement of “not collapsing in the strong earthquake” under the action of the earthquake . When the peak acceleration of the ground motion is 0 .1g ,0 .21g ,0 .32g ,0 .38g and 0 .57g ,the minimum reinforcement ratios for the low and medium height piers are respectively 0 .1% ,0 .2% ,0 .3% ,0 .4% and 0 .5% .The influ‐ences of the field conditions on the seismic responses of the piers are significant and w hen the field condition is poor ,the reinforcement ratios for the piers should be increased and the seismic meas‐ures should be strengthened .