钢筋混凝土梁变幅滞回耗能能力衰变规律试验研究

Experimental study of plastic energy dissipation capacity deterioration of RC beams under variable amplitude loading histories

在基于能量的结构性能设计方法中,需要根据耗能需求对构件进行能力设计,而了解位移历程和配筋状况对构件滞回耗能能力的影响规律是实现这一步骤的基础。通过对22根钢筋混凝土梁试件分别采用稳态变幅加载和任意变幅加载,分析位移历程、配箍率和配筋率的变化对钢筋混凝土梁滞回衰变规律的影响。研究表明,常幅滞回条件下,增加配箍率能够延缓钢筋混凝土梁滞回耗能能力的衰变过程,其延缓效果随滞回幅值的增大而降低;配筋率的变化对构件耗能能力的衰变过程未见规律性的影响;相对于配箍率与配筋率,滞回位移幅值的影响更为明显且更具规律性,滞回位移幅值越小,构件衰变至稳定的过程会更快,而衰变稳定后的残余耗能能力将更高。变幅滞回条件下,钢筋混凝土梁在某个半滞回的耗能能力决定于历史最大位移和已累积耗散的滞回能量,即钢筋混凝土梁的滞回耗能能力受最大历史位移和累积耗能的双控。基于这一双控规律,通过量化箍筋与滞回位移幅值对构件滞回耗能能力衰变的影响,提出了钢筋混凝土梁变幅滞回耗能能力的估计方法。

During the energy-based seismic design procedure for structures,structural members need to be designed based on hysteretic energy demand,and understanding the effects of the loading history and reinforcement conditions on energy dissipation capacity of structural members is the basis for this step. In this paper, deterioration characteristics of energy dissipation capacity for 22 reinforced concrete beam specimens with different stirrup ratios and reinforcement ratios under various displacement reversals were investigated. The results show that,under the constantamplitude displacement cycles, increasing stirrup ratio of beams can delay the energy dissipation capacity deterioration,and the delay rate is decreased with cyclic amplitude. The effect of reinforcement ratio on deterioration characteristics of energy dissipation capacity lacks regularity. Relative to the stirrup ratio and reinforcement ratio,cyclic amplitude effect is more obvious and more regular. The smaller cyclic amplitude would lead to the faster decay process of deterioration and the greater residual energy dissipation capacity. Under the variable-amplitude displacement cycles,the remaining energy dissipation capacity in a forthcoming displacement cycle is dependent on both the relative relationship between the maximal displacement cycle and the energy dissipated along the completed displacement path.Plastic energy dissipation capacity of reinforced concrete beams are both displacement path dependent and cumulative hysteretic energy dependent. Based on this double-dependency rule,a method was developed in order to predict the energy dissipation capacity of reinforced concrete beams subjected to random variable amplitude displacement cycles simulating severe seismic excitations.