现浇楼板对混凝土框架结构耗能分布的影响

为了研究现浇楼板对混凝土框架结构各构件滞回耗能分布的影响,基于多弹簧杆单元分别建立了矩形梁、考虑梁刚度、强度增强效应的矩形梁以及考虑楼板翼缘的T形梁共4个多层框架结构计算模型,进行了8度罕遇地震作用下结构滞回耗能分布比较分析。计算结果表明:梁强度增大使结构总滞回耗能增加,而梁耗能占总耗能的比例有所下降;梁刚度增大使得结构总滞回耗能略有增加,梁耗能占总耗能比例也有所上升。考虑楼板翼缘作用的T形梁对结构滞回耗能沿层分布、各层梁柱构件之间分布的影响主要体现在梁强度的增大,梁刚度的增大则会使滞回耗能分布产生突变,框架内梁滞回耗能小于外梁而边柱滞回耗能小于中柱。塑性铰的演化过程体现了结构耗能的转移过程,楼板翼缘作用可使结构由"梁铰机制"转为按"柱铰机制"破坏,这说明了楼板翼缘作用对于结构耗能分布的影响不可忽略。

The Influence of Cast-in-Place Slab on Distribution of Hysteretic Dissipative Energy for Reinforced Concrete Frame Structure

This paper establishes calculation models of four multilayer frame structures based on the multispring rod unit, in the light of the influence of cast-in-place slab on the hysteretic dissipative energy distribution of concrete frame structure members. The target structures include a rectangular beam model, a rectangular beam model with consideration of reinforced stiffness, a rectangular beam model with consideration of reinforced strength and a T-beam model with consideration of the flange slab. The paper also describes the hysteretic dissipative energy distribution on structure under rare occurrence earthquake of 8.0 seismic fortification intensity for comparative analysis. The calculation results show that, with the increase of beam strength, the total hysteretic dissipative energy on structure increases while the ratio of the dissipative energy of beam to the total dissipative energy decreases; and with the increase of beam stiffness, the total hysteretic dissipative energy on structure increases and the ratio of the dissipative energy of beam to the total dissipative energy also increases. With consideration of the effect of slab flange, the increase of T-beam strength obviously influences the distribution of dissipative energy on each layer and between beams and column members. The increase of beam stiffness makes sudden change on the distribution of hysteretic dissipative energy. The hysteretic dissipative energy of an inner beam on each layer is less than that of an outer beam and the hysteretic dissipative energy of a side column is less than that of a center column. The evolution course of plastic hinge reflects the transfer of dissipative energy of structure. Under the action of flange slab, the structure is damaged in the pillar-hinge manner instead of the original beam-hinge manner, proving that the influence of the slab flange on the dissipative energy of structure cannot be ignored.