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以一座由简支橡胶支座支撑的多跨混凝土桥梁为实例,对桥面的滑移和回填土桥墩的碰撞进行了研究。在1999年的集集地震中,该桥遭受了水平和竖直两个方向的地震作用。为考虑土壤-结构的相互作用,回填土的刚度和强度常数由桥墩的倾角和回填土的支座反力共同决定。为评估桥梁的性能,将时程分析法应用在离散的质点-弹簧模型上,模拟大量的非线性行为,包括支座的摩擦滑移,桥面和桥墩的碰撞反应和回填土的弹塑性压缩量。模型中的主要参数包括伸缩缝间距、支座的摩擦系数和土壤的强度极限。模拟结果证实,支座垫上的摩擦滑移和回填土的塑性变形是避免强烈地震中桥面坍落的关键因素。模型中支座的摩擦系数为0·1~0·2,桥墩在碰撞中产生的最大倾角减少了1/10。甚至当土壤强度降低一半时,桥面的最大位移变化也不会超过两倍。在任何一种情况下,桥面的倒塌都不太可能发生。
Taking a multi-span concrete bridge supported by a simply supported rubber bearing as an example, the collision between the deck slip and the backfill pier was studied. During the 1999 Jiji earthquake, the bridge suffered horizontal and vertical seismic effects. In order to consider the soil-structure interaction, the stiffness and strength constants of backfill soil are determined jointly by the angle of the pier and the reaction force of the backfill soil. To evaluate the performance of the bridge, the time-history method is applied to the discrete particle-spring model to simulate a large number of nonlinear behaviors, including the friction and slip of the abutment, the collision reaction between the bridge deck and piers, and the elasto-plastic compression the amount. The main parameters of the model include the expansion joint spacing, the friction coefficient of the support and the soil strength limit. The simulation results confirm that the friction slip on the support pad and the plastic deformation of the backfill soil are the key factors to avoid the slump of the deck during strong earthquakes. The friction coefficient of the bearing in the model is between 0.1 and 0.2, and the maximum inclination of the pier in the collision is reduced by 1/10. Even when the soil strength is reduced by half, the maximum displacement of the bridge deck will not change more than twice. In either case, the collapse of the deck is less likely to occur.