巨型钢框架—预应力支撑体系预拉力取值准则试验

Experimental Study on Rule of Prestress in Steel Mega-Frame-Prestress-Braced Structure

目的研究巨型钢框架—预应力支撑体系的工作机理,获得其预拉力取值准则.方法进行室内模型试验,在不同的初始预拉力下,对模型进行横向加载到额定荷载,记录加载过程中受压索传感器示数为零时对应的外荷载和此时受拉索的剩余索力,以及相应的顶点侧移.结果巨型钢框架—预应力支撑可以减小结构的整体侧移,提高结构抗侧刚度;初始阶段,结构抗侧刚度随拉索预应力增大而增大,当拉索预应力增加到一定程度时,结构抗侧刚度几乎不变;预拉力以在外部作用下受压预应力支撑剩余拉力接近零为准则.结论验证了竖向预应力钢结构体系拉索预拉力取值一般准则的正确性:使得结构在外荷载作用下,受压最大的拉索剩余拉力接近于零.

The aim is to obtain the rule of prestress of brace in steel mega-frame-prestress-braced structure through studying the work principle of the structure. An indoor model test is done to study the characteristics of steel mega-frame-prestress-braced structure with different initial tensile force. External loads are recorded at the time of sensor reading of compressed cable is zero in loading process. Residual force of tensioned cable and apex side-movements at that time are also recorded. The relationship between pre-tension force and lateral stiffness, relationship between pre-tension force and residual cable force are obtained. The results indicate that prestressed brace can improve lateral stiffness of structure. Under determinate direction load, compression brace has adverse effect on controlling lateral displacement. And lateral stiffness of the structure is increasing with the increased prestress force of cable in initial stage. Then, lateral stiffness almost unchanged when prestress force increases to a certain value. Initial prestress value should comply with the rule that residual tension in compression brace is near to zero under exterior loads. The correctness of rule of vertical prestress steel structure system＇s cable pretension is verified. That is value of residual tension of cable which is beraing the most of compression is near to zero under exterior loads.