拟静力试验装置比较与改进

Improvement and comparison on pseudo-static test device

为了精确地模拟建筑结构的实际受力情况,减少试验装置对试件加载过程中的影响,对比分析了不同类型的拟静力试验装置。通过分析拟静力试验装置的加载特征,提出了改进方法。首先,计算了反力横梁引起的附加水平荷载,计算结果表明由试验装置引起的附加水平荷载对开裂荷载或屈服荷载的影响可以达到5.07%~33.39%,因此在进行拟静力试验之前,应确定导轨的摩擦系数,考虑导轨摩擦力对试验结果的影响。其次,将带有球铰的竖向千斤顶倒置安装,可以保证竖向荷载的稳定性;用高精度油压传感器代替荷载传感器,可以减少试验安装的工作量。再次,对于上部设有可移动反力横梁的墙、柱拟静力试验装置,在移动反力横梁上部设置固定横梁,能够抵消由高强钢棒引起的附加水平荷载;在试件底部设置钢梁,与高强钢棒、可移动反力横梁组成自反力体系,可以降低静力台座设计难度。最后,当梁柱节点拟静力试验采用柱端加载方式时,用两根钢索代替支承连杆,用铁环或U形环代替铰支座,可以避免连杆失稳破坏。

In order to simulate the actual mechanical behavior of structural elements and reduce the impact of the additional load caused by test devices on specimens, this paper compared and analyzed different types of pseudo-static test devices. Some problems were found, and some measures to improve pseudo-static test devices were presented after analyzing the loading characteristics of the test device. Firstly, we calculated the additional horizontal load caused by the reaction beam, and the results showed that the impact of the additional horizontal load on cracking load or yield load can reach 5.07%~33.39%, so the friction coefficient of the guide rail should be determined beforehand, and the impact should be subtracted when processing the test data. Secondly, the vertical jack with ball hinge should be inverted to ensure the stability of the vertical loads and high precision oil sensors can be substituted for the load sensors so as to reduce the amount of test equipment installation. Thirdly, in case of pseudo-static test devices with movable counter-force beam, a fixed beam can be installed on the upper of the movable counter-force beam so that the additional horizontal load can be offset rather than exert on the test specimen;a high-strength steel beam can be arranged at the bottom of the test specimen so the self-reaction force system is formed to reduce the design complexity of the static pedestal. Finally, when pseudo-static test of beam column joints adopts the method of loading at the end of the column, the instability and failure of the connecting rod can be avoided by replacing the supporting connecting rod with two steel cables and replacing the hinged support with iron ring or U-ring.