摘要:
以某梁板高支模架倒塌事故为背景,分析高支模架倒塌原因是没有按照规范构造要求搭设;分别应用刚性节点和铰接节点模型分析脚手架竖向剪刀撑的重要性,发现对于铰接节点模型,加上剪刀撑以后使基本单元从几何可变体系变为几何不变体系;对于刚接节点模型,建模分析计算发现,立杆在加上剪刀撑后构件的轴力要比没有加剪刀撑时轴力减少25%以上。对倒塌区域拆除方案进行讨论,在拆除之前先搭设生命线;对于Ⅰ区塌陷部分,先将梁之间的板凿碎卸载,留下主梁和板带;同时钢筋网不割断,以维持其平衡状态,待模架加固以后才拆除大梁;对于Ⅶ区已经严重外凸变形的外脚手架,拉设了网状钢丝绳进行固定。最后确定了整体拆除顺序,顺利拆除了塌陷部分。
Abstract:
Based on the collapse of the high scaffolding for bracing forms,the cause of collapse was analyzed;it was that the constructional requirements of standard were not met.The importance of vertical cross bridging of the scaffolding was analyzed by the rigid-connected and the hinged models respectively.It was found that variable geometry system had become the invariable one for the hinged model when the cross bridging was added to the scaffolding;on the other hand for the rigid-connected model,the axle force of the vertical bar was reduced by more than 25% compared with that of the one without the cross bridging.The removing scheme was discussed.The secure line was set up before the removal work began; for the collapsed in zone Ⅰ part,the concrete plate was removed firstly.At the same time the main beam and the mesh reinforcement were remained to keep the force balance.The steel wire netting was set up on the surface of the deforming scaffolding in zone VII to strengthen the scaffolding.At last,the removal sequence of the whole structure was determined and the collapsed part was removed smoothly.