大跨径连续刚构桥梁底维修平台设计

Design of Maintenance Platform Below Girder of Long-Span Continuous Rigid-Frame Bridge

某大跨径跨海大桥主桥为(124.4+170+124.4)m预应力混凝土连续刚构桥,为对该桥进行裂缝处理、混凝土表面缺陷修复及防护涂装,需在梁底下部搭建维修平台。结合该桥结构特点和桥下通航净空要求,维修平台采用倒梯形吊挂式钢管脚手架结构,由Φ48mm×3.5mm钢管拼装成顺桥向每2m一道的横向支撑架,再由纵向钢管连接形成全封闭的梁底施工平台。采用有限元软件建立跨中及墩顶典型部位8m长倒梯形吊挂式钢管脚手架平台结构局部模型,经计算平台结构强度、刚度及稳定性均满足要求。实践证明该平台施工过程安全可靠。

The main bridge of a long-span sea-crossing bridge is a prestressed concrete continuous rigid-frame bridge with span arrangement of（124.4＋170＋124.4）m.To treat the cracks in the bridge,restore the surface defects of concrete and carry out prevention coating,a maintenance platform must be erected below the girder.By the consideration of the structural characteristics of the bridge and the requirements of the navigational clearance,the maintenance platform adopts the under-hung inverted trapezoidal scaffolding structure made of steel tubes.The steel tubes of48mm×3.5mm were assembled to form transverse supporting frames with 2mintervals along the bridge length,which were then connected by longitudinal tubes to form a fully-closed construction platform below the girder.The local finite element models of the 8 m long under-hung inverted trapezoidal scaffolding construction platform made of steel tubes at the locations of the mid-span and pier tops were established.The results of the calculation show that the structural strength,stiffness and stability of the platform meet the requirements.The engineering practice proves that the maintenance platform could ensure safe and reliable construction operation.