作为能力保护构件的桥梁群桩基础设计地震力简化计算方法

在桥梁延性抗震设计中,群桩基础往往作为能力保护构件进行设计。基于这一设计方法,计算群桩基础的设计地震力时,需要计算承台的地震惯性力。该文建立了承台-墩梁两质点模型,分析了承台惯性力随桥墩刚度的变化规律,提出了承台地震惯性力的简化计算公式,以及群桩基础的设计地震力简化计算公式。最后,以实际桥梁工程为背景建立有限元计算模型,通过弹塑性时程分析验证了简化计算公式的正确性和实用性。

Simplified Calculation Formula for Design Seismic Force of Bridge Group Pile Foundation as Capacity Protective Member

In the seismic design of bridges ductility,the foundation of group pile is designed as the capacity protective member sometimes.Based on this design method,it is required to calculate the seismic inertial force of base slab when the design seismic force of the foundation for the group pile is calculated.The article sets up a two-particle model of base slab-pier beam,analyzes the variable rule of the inertial force of base slab with the variation of pier rigidity,and puts forward the simplified calculation formula of seismic inertial force of base slab and the simplified calculation formula of the design seismic force of the foundation for the group pile.Finally,a finite element model based on a practical bridge project is established.The correctness and practicability of the simplified calculation formula is validated by the elastoplastic time-history analysis.