火灾后再生混凝土型钢构件力学性能研究

Study on mechanical performance of shaped steel member of recycled concrete after fire disaster

针对国内废弃混凝土循环利用率低的问题,本文通过对再生骨料混凝土的研究,结合H型钢混凝土柱刚度大、承载力高、抗震性能好等特点,制备了H型钢再生混凝土(H-RC)柱,对其火灾后的粘结性能及轴压性能展开分析研究。研究结果表明:随再生细骨料(RFA)替代率的提高,再生混凝土立方体抗压强度逐渐降低;试件的质量损失率随着RFA取代率的增加而逐渐增大,同时构件的火灾抗裂性能降低。试件的受火温度越高,质量损失越严重。RFA取代率100%试件的压缩变形呈明显的三阶段,最终的破坏荷载稳定在55%~65%极限荷载;受火温度的升高能明显降低,H-RC构件的承载力及型钢与混凝土之间的粘结力,取代率100%的H-RC构件易压缩。研究结果对于合理评估火灾后型钢混凝土结构的力学性能具有重要意义,旨在推动再生混凝土在建筑中的大量运用。

Aiming at the problem of low cyclic utilization rate of waste concrete in China,the H-shaped steel recycled concrete(H-RC)column is prepared in combination with its characteristics of high stiffness,high bearing capacity,better seismic performance,etc.through the study made on the recycled aggregate concrete,and then the bonding performance and axial compression property of it after fire disaster are analyzed and studied.The study result shows that the compressive strength of the recycled concrete cube is to be gradually decreased along with the increase of the replacing rate of the recycled fine aggregate(RFA),while the mass loss rate of the test specimen is to be gradually increased along with the increase of the RFA replacing rate,meanwhile,the crack resistance of the structural member for fire disaster is to be decreased as well.The higher the fired temperature of the structural member is,the more serious the mass loss is to be.The compressive deformation of the test specimen with the RFA replacing rate of 100%exhibits obvious three stages and the final failure load is stabilized at the ultimate load of 55%~65%,while the increase of the fired temperature can obviously decrease both the bearing capacity of the H-RC structural member and the bonding capacity between the shaped steel and the concrete,of which the H-RC structural member with the replacing rate of 100%is prone to be compressed.The study result has an important significance for reasonable assessment of the mechanical performance of the shaped steel concrete structure after fire disaster,so as to promote the massive application of the recycled concrete to construction.