长悬臂板在作业平台荷载下的力学行为分析

Analysis on Mechanical Behavior of Long Cantilever Plate under Work Platform Load

当箱梁结构的悬臂翼缘长度达到和超过2.5m时,可以通过配置横向预应力钢筋以优化顶板及悬壁板的应力状态,而由于施工工艺或张拉控制的影响,可能会造成横向预应力损失过大或失效,从而导致长悬臂翼缘板在重载作用下损伤和破坏。文章以实际工程为例,分别考虑了横向预应力失效和不失效两种情况,对箱梁长悬臂翼缘上搭设作业平台的力学性能进行了线性和非线性分析。结果表明:箱梁长悬臂板设置横向预应力钢筋能够提高悬臂结构正常使用阶段的安全性,但不能提高其极限承载力,极限承载力取决于翼缘混凝土的强度和尺寸以及翼缘中普通钢筋的有效配筋率,同时长悬臂结构配置的横向预应力实际上消弱了结构本身的稳定性。

When the cantilever flange length of box girder structure reaches and exceeds 2.5m,the stress state of roof and cantilever plate can be optimized by configuring the transverse prestressing steel,but be-cause of the impact by construction process or tension control,it may cause the great loss or failure of trans-verse prestress,leading to the damage and destruction of long cantilever flange plate under heavy load.Tak-ing the actual engineering as the example,and considering respectively both situations of invalid and valid transverse prestress,this article conducted the linear and nonlinear analysis on the mechanical properties of work platforms erected on long cantilever flanges of box girder.The results showed that:the transverse pres-tressed steel installed on long cantilever plate of box girder can improve the safety of cantilever structure dur-ing normal usage,but it can not increase its ultimate bearing capacity,and the ultimate bearing capacity de-pends on the strength and size of flange concrete as well as the effective reinforcement ratio of ordinary steel in the flange,while the transverse prestress configured in long cantilever structure can actually weaken the stability of structure itself.