Analysis On Influencing Factors To Stability Bearing Capacity Of The Steel Tube Formwork Support With Couples And Study On Construction Measure

The steel tubular formwork support frame with couples is mostly widely used in the cast-in-place concret structure recently in China because it is convenient, versatile, high carrying capacity and relatively inexpensive. However, because of the uncertain and unsafe factors during designing calculation and practical building of this frame, collapses of support frame frequently take place, which results in substantial ecomomic loss and casualties. Therefore, the study on this kind of support frame has important theoretic and practical meanings.Based on other's works about support frame, the author performed following works through collecting materials, analysis and calculation:(1) On the basis of the analysis and summarization of some typical support frame collapse accidents happened in recent years in China, this thesis completely analyzed the reasons of collapses and its preventive countermeasures from the angles of technology and management.(2)After summarizing several calculation methods of carrying capacity, the emphasis is put on the discussion about the the applicability and defects of the calculation method in current codes. The author holds that the overall stability factors were not considered in the calculation method of current codes with the unseriousness of standing rod's calculation length and the application premises of the method is strict assurance of construction measures.(3)Through using SAP2000 to establish the space 3D model of the bracing system and simulating the performance, the paper analyzes the affects of various factors to the bearing capacity, such as the floor members, step length, span, bridging in horizontal planes, bridging in uprightness planes, wall-linking element, height, height-width ratio, thickness of steel pipe, the routing of casting concrete and so on. The analysis shows that all various factors have influence on the bearing capacity with different degrees and the floor members, bridging and wall-linking element are the most critical structural factors.(4)In view of the construction requirements of formwork support frame are not quite uniform in the preesent code system and easily produce ambiguity without drawing description, the thesis systemized and summarized all the details and requirements with drawing of most details for the first time, which are effective for the carrying capacity. Considering the importance and complexity of the wall-linking element, the paper makes a valuable exploration to the setting methods and draw some conclusions which could provide available and useful references to the safety of practicing the steel tubular formwork support frame.