The Optiml Shape and Bracing Way for Scaffold Shores

在營建工程災害中，模板支撐倒塌意外在營建工程災害中所佔比例約 為20%，由於模板支撐的倒塌是大面積大區域的破壞，造成現場營建人員 集體性的傷亡，對於生命、財產造成嚴重的損失。有鑑於此，國內外學者 已紛紛投入模板支撐相關研究，且已穫初步成果。本論文主要探討鋼管鷹 架外觀形狀的不同對其支撐能力之影響及鋼管鷹架連接法之研究。利用 ANSYS有限元素法分析軟體進行數值分析，並配合鷹架試驗驗證。結果顯 示，鋼管鷹架形狀對支撐能力影響，其補強桿件形狀以直線型補強桿件為 最佳。補強桿件與水平桿件之接點位置以水平桿件中心點為最佳(Kw=1.0) ；與垂直桿件之接點位置以垂直桿件中心點偏上方為最佳(Kv=0.4)。就經 濟效益而言，亦可得到相同之結果。水平桿件長度對其承載能力並無明顯 之影響。鋼管鷹架支撐系統承載能力隨搭設層數增加而折減，其折減量隨 著層數的減少而趨於平緩。對於鋼管鷹架模板支撐系統in-plane方向上之 側向支撐位置，以架設於第一層與第二層鷹架間為最佳，至於其上方各層 側向支撐效果則不明顯。但需各排均加上側向支撐才能達到有效的支撐效 果。out of plane上交叉拉桿只要不是水平搭接，其與鋼管門型鷹架之連 結位置對鋼管門型鷹架之承載能力並無明顯之影響。in-plane方向上大型 竹材交叉拉桿對承載能力有改善作用，但需在系統內外各排均加上大型竹 材交叉拉桿才能達到有效的支撐效果。鋼管鷹架模板支撐系統之承載能力 將隨大型交叉拉桿之勁度增加而增高，但其效果並不明顯，所以建議以普 通經濟材料取代即可。The main objective of the study is the influence on the load-carrying capacity of the door-type steel scaffolds with different shapes and bracing locations. The research work includes indoor experiments and numerical analysis. The indoor experiments were carried out to obtain the critical loads and the failure modes of the one-story and two-story door-type steel scaffolds with different shapes. The finite element analysis software "ANSYS" is used for the numerical analysis. Both the experimental and numerical results show that the optimal shape of steel scaffold should be like the following: the subframe is straight; the connected location between the subframe and the horizontal bar is at the midpoint of the horizontal bar (Kw=1.0); the connected location between the subframe and the vertical bar is near the midpoint of the vertical bar (Kv=0.4). This optimal shape for load is also almost the most economical shape. The results also show that the length of the horizontal bar has no obvious influence on the load-carrying capacity. The load-carrying capacity of steel scaffold system is decreasing as the number of the stories is increasing. The optimal lateral bracing locations in the in- plane direction are between the first and the second stores. They must be braced for all rows of the steel scaffold system. The cross-brace locations in the out-of-plane direction have no obvious influence unless they are totally horizontal. The large size bamboo cross braces can improve the load-carrying capacity of the steel scaffold systems. It is effective only when all rows are tied with bamboo cross braces. The load-carrying capacity will increase as stiffness of the large size bamboo cross braces increase, but the effect is not obvious. Therefore, the economical material for the large size bamboo cross braces are recommended