预应力自复位装配式混合框架结构抗震性能试验研究

Experimental study on seismic performance of prestressed self-centering precast steel-concrete hybrid frame structures

为了提高传统装配式混凝土结构的抗震能力,结合螺栓连接的施工性能、后张预应力筋的复位性能和腹板摩擦装置的耗能性能优势,提出一种预应力自复位装配式混合(SPH)框架结构。SPH框架结构由预应力钢筋混凝土柱和预制预应力钢-混凝土混合梁通过高强螺栓拼装而成,主要通过布置在梁与柱内的后张无黏结预应力筋提供复位力,通过混合梁内的摩擦装置与钢梁段的塑性变形进行耗能。完成了1榀无预应力装配式混合(NPH)框架及2榀SPH框架的低周往复加载试验,分别考虑了预制梁、柱内预应力筋初始预应力、摩擦装置处高强螺栓初始预紧力及柱脚构造措施对该类结构承载能力、复位性能及耗能能力等抗震性能的影响。研究结果表明:采用千斤顶非接触锚具的后张预应力筋方法行之有效;SPH框架相较于NPH框架表现出更好的承载性能、复位效果、变形及耗能能力;SPH框架表现出明显的两阶段特征,即在位移角2.0%以前,结构整体表现为“强复位、低耗能”特点,可以有效控制残余变形,相对自复位率保持在85%左右,在位移角2.0%以后,结构整体表现为“弱复位、强耗能”特点;整个试验过程中SPH框架主体构件损伤不明显,基本实现震后可恢复功能。

To improve the seismic performance of traditional precast concrete structures,an innovative self-centering prefabricated steel-concrete hybrid(SPH)frame structure was proposed,which combines the advantage of bolted connections in mechanical behavior,that of post-tensioned connections in self-centering performance and that of steel friction devices in energy dissipation performance.The proposed SPH frame structure is assembled by pre-stressed reinforced concrete columns and pre-stressed steel-concrete hybrid beams using high-strength bolts.Its resilient ability is mainly provided by the unbonded post-tensioned strands in the beams,while the friction devices and plastic deformation of the steel beam ends provided the energy dissipation capacity in the structure.Quasi-static tests were conducted on one non-prestressed precast steel-concrete hybrid(NPH)frame specimen and two SPH frame specimens to investigate their seismic behavior.The effects of initial prestress in the beams and columns,the initial pretension force of the high-strength bolts at the friction device and the construction details at the column base were critically investigated.The test results indicate that the proposed post-tensioned strands method,in which no contact between the oil jack and the anchorage is needed,is verified to be reliable.The SPH frame shows better performance than the NPH frame in terms of the bearing capacity,self-centering effect,deformability and energy dissipation performance.The SPH frame exhibits obvious two-stage hysteresis behaviour.In the first stage(before the displacement angle reaches approximately 2.0%),the overall structure behaves following the principle‘strong self-centering,weak energy dissipation’,in which the structure can effectively control the residual deformation,and the self-centering ratio remains at approximately 85%.In the second stage(after the displacement angle reaches approximately 2.0%),the overall structure behaves following the principle‘weak self-centering,strong energy dissipation’.During the entire test process,the damage of the main structural components of the SPH frame is not obvious,indicating that the post-earthquake recoverable performance is basically achieved.