橡胶隔震支座安装螺栓受力特性的试验研究

Experimental study on mechanical characteristics of anchor bolt for rubber isolation bearing

为研究橡胶隔震支座与隔震支墩螺栓连接部位在竖向及水平地震作用下的受力特性,分别对直径600mm和700mm的铅芯隔震支座进行了竖向和水平剪切变形加载的试验研究。为模拟钢筋混凝土支墩与支座连接面的接触特性,在支座的底部设置了一块50mm厚的钢筋混凝土板。支座竖向加载后,预紧的螺栓出现了应力松弛现象。面压12MPa的支座发生剪切变形时与面压0MPa的支座发生剪切变形时螺栓的轴力变化历程虽有较大差异,但达到水平极限剪切变形时,两种情况下受拉侧螺栓拉力值接近。根据《橡胶支座第3部分:建筑隔震橡胶支座》(GB 20688.3—2006)附录G中的公式计算的隔震支座安装螺栓的拉力也与试验值接近。此外试验中出现了钢筋混凝土板角部混凝土开裂和脱落的现象,说明螺栓会在螺孔产生较大的外劈作用力,实际工程中应予以注意。

To study the mechanical characteristics of bolt connection parts of rubber isolation bearings and isolation piers under vertical and horizontal earthquake loads, experimental studies were conducted on vertical and horizontal shear deformation loading of lead core isolation bearings with diameters of 600mm and 700mm respectively. In order to simulate the contact characteristics of the reinforced concrete pier and the bearing connection surface, a reinforced concrete slab with 50mm thick was set at the bottom of the bearing. After the bearing was loaded vertically, the stress relaxation phenomenon was appeared in the pre-tightening bolt. There is large difference between bolt axial force variation processes in bearing shear deformation with surface pressure of 12MPa and OMPa respectively, but tension-side bolt tension values for the two conditions were close when achieving the ultimate horizontal shear deformation. According to the formula of Appendix G of Rubber bearings-third part： building isolation rubber bearings （ GB 20688.3-2006 ）, the calculated isolation bearing installation bolt＇s tension is also close to the test values. In addition, the phenomena of corner concrete cracking and peeling in reinforced concrete slab appear in experiment, which indicates that the bolt will generate large splitting force in screw holes and attention should be paid for this in practical engineering.