空间管桁架结构胎架同步卸载偏差分析及现场监测

Synchronization and Unloading Deviation Analysis and Site Monitoring of Space Tube Truss Structures

为了提高施工精度,对某体育场管桁架罩棚设置一定的临时支撑胎架。罩棚桁架间连接杆件安装完毕后进行胎架卸载,这个过程是胎架逐步退出工作,主体结构逐步承担荷载的转换过程。施工过程中由胎架和结构共同受力,在胎架拆除过程中逐渐变为由结构独自受力,该过程对结构而言就是反向加载。针对此种情况,对某体育场进行卸载偏差分析研究。运用有限元软件对局部模型和整体模型的卸载进行非线性分析,发现钢罩棚在卸载过程中位移和应力较卸载前变化明显。同时对比分析卸载出现偏差的情况,每级卸载量不均匀发生在不同桁架上时,结构中的应力、位移最大位置及卸载后结构形态均与设计不吻合,出现了6%以内的误差;而每级卸载量不均匀发生在同一桁架的不同支点处,会引起结构受力的改变,应力、位移均与设计值产生约10%的误差。

In order to improve construction accuracy,some temporary support frame for a stadium tube truss cover shed are provided.After the installation of the canopy shed truss connection rod rack unloading,this process is the gradually pulled back from the work of tire rack,the main structure gradually takes the loading conversion process.During the construction process,the common force is applied by the tire frame and structure,and gradually takes the loading of the structure during the process of removing tire frame.The process is reversely loaded to the structure.In view of this situation,this carries on unloading deviation analysis research to a certain stadium.Finite element software is used to analyze the unloading of local model and whole model.It is found that the displacement of the steel canopy during the unloading process changes obviously.At the same time,the deviation of unloading is compared and analyzed.When the unloading of each level occurs unevenly on different truss,the maximum position of stress and displacement and the structure after unloading are not consistent with the design,and the error is less than 6%.Uneven unloading occurs at different fulcrums of the same truss,which will cause changes in the structure stress.The stress and displacement both produce about 10% error as compared to the designed value.