具有抗拉功能的隔震支座力学性能试验研究

Experimental research on mechanical properties of anti-tension isolation bearing

在某些特定情况下,隔震结构底部会产生拉力,由于普通隔震支座受拉能力较差,从而导致隔震层破坏。为此,提出具有抗拉功能的铅芯叠层橡胶支座(TLRB),与普通铅芯橡胶支座(LRB)相似,该支座具有较小的水平抗侧刚度,以隔绝水平地震能量输入,在大剪切应变时提供稳定的水平刚度和恢复力,同时可以有效承受拉力。通过试验对TLRB试件的偏压、偏拉刚度及拉压状态下的水平刚度等特性进行了研究,并对其极限压缩、拉伸及剪切等性能进行了分析。同时对LRB试件进行了对比试验。试验结果表明,TLRB具有可靠的受拉特性及良好的水平刚度特性,试验测得的TLRB最大受拉应力达3.51 MPa,远大于LRB的极限受拉应力;在受压状态下,当剪切应变从100%増大到250%时,TLRB的水平等效刚度减小了10.7%,而LRB水平等效刚度则减小了52.9%。根据试验结果及橡胶体弹性理论,给出了TLRB在受压、受拉状态下的水平刚度计算式,建立了支座极限剪切应变计算式,确定了TLRB在拉-剪作用下不会发生破坏的安全范围。数据分析表明,采用建议相关计算式的计算结果与试验结果吻合较好。

Under certain conditions, potential tension forces may generate at isolation floor and lead to the fracture of bearings because of their low tensile capacity. For this reason, a new isolation device-anti-tension lead core laminated rubber bearing （TLRB） was designed. Analogous to common lead core rubber bearing （ LRB）, the TLRB can isolate the horizontal earthquake energy with small shear stiffness. Furthermore, the TLRB has excellent tension resistant capacity and can provide stable shear stiffness and restoring force at large shear strain. A series of tests were performed to investigated the mechanical properties of TLRB, such as eccentric-compressive stiffness, eccentric-tensile stiffness, shear stiffness, limit compressive and tensile performances. In order to have a basis for comparison, the same tests were carried out for LRB at the same time. The results of the tests show that the TLRB has more desirable tensile capacity and shear stiffness than LRB. The maximum testing tensile stress of TLRB is 3.51 MPa, which is much larger than the limit tensile stress of LRB. The equivalent shear stiffness of TLRB is decreased by 10. 7% under compression, whereas this value for LRB is 52.9% , when shear strain is increased from 100% to 250%. Based on the testing results and elastomeric rubber theory, the formulae of horizontal stiffness at different vertical stress states was proposed, and the model for limit shear strain was developed at the same time. The data analysis reflects that there are good agreements between these theoretic formulae and testing results.