反吊平台在桥梁维修加固中的应用研究

Application Research of Reverse Platform in Bridge Maintenance Reinforcement

桥梁的主梁维修加固时需要作业人员前往桥梁下方作业,在桥梁下部无法搭设落地支架的情况下,就需要搭设一个反吊平台用于桥梁维修加固。为研究反吊平台应用在桥梁维修加固中的可行性,本文分析了反吊平台的受力性能,说明了平台的结构组成及其施工方法,并计算分析了某反吊平台在承载能力极限状态下的强度和刚度,计算思路与扣件式支架类似,施工荷载按装修脚手架取值。反吊平台的主要受力构件为吊杆、吊杆上部的膨胀螺栓、吊杆下部的横向支撑钢管,经分析反吊体系受力性能良好,能承担施工时的人群机具荷载。本文所述施工案例中膨胀螺栓和横向支撑钢管的安全系数均不大于2,安全系数富余量较小,反吊平台的承载能力主要取决于膨胀螺栓抗拔强度和横向支撑钢管抗弯强度,而不取决于纵向钢管强度,安全起见应根据计算结果适当降低膨胀螺栓间距和横向支撑钢管跨度。

During the maintenance and reinforcement of the main beam of the bridge,operators need to work under the bridge.When the floor support cannot be erected at the lower part of the bridge,an anti lifting platform needs to be erected for bridge maintenance and reinforcement.In order to study the feasibility of the application of the anti lifting platform in bridge maintenance and reinforcement,this paper analyzes the mechanical performance of the anti lifting platform,explains the structural composition and construction method of the platform,and calculates and analyzes the strength and stiffness of an anti lifting platform in the limit state of bearing capacity.The calculation method is similar to the fastener support,and the construction load is taken according to the decoration scaffold.The main load-bearing components of the reverse hoisting platform are the suspender,the expansion bolt at the upper part of the suspender and the transverse supporting steel pipe at the lower part of the suspender.After analysis,the reverse hoisting system has good stress performance and can bear the loads of people,machines and tools during construction.In the construction case described in this paper,the safety factor of expansion bolt and transverse supporting steel pipe is not greater than 2,and the margin of safety factor is small.The bearing capacity of the anti-lifting platform mainly depends on the pullout strength of expansion bolts and the bending strength of transverse support steel pipes,not on the strength of longitudinal steel pipes.For safety reasons,the spacing of expansion bolts and the span of transverse support steel pipes should be appropriately reduced according to the calculation results.