Study Of The Ultimate Bearing Capacity Of Full-hall Formwork Support System With Mortise And Tenon Joints

With the rapid development of China's economy, the urban construction and the construction of urban public infrastructure has entered a peak period, the building structures have become higher or with larger span; Providing support for the construction or operation platform for the erection of building structures, scaffolding sysem will also get into the direction of becoming higher or with larger span. Currently, only in domestic area, there are many types of scaffolding systems, such as: fastener scaffold, Bowl-Scaffold Support system, disc-type scaffold, gate-type scaffold. Although many types of scaffolding are used on construction site and we can say that we've already got everything. However safety accidents occur frequently, the collapse of scaffolding bearing system seems the most commonly happened safety accident on construction site. So, finding a more reasonable, safer, more economical scaffolding bearing system becomes a popular voice.This article describes the most commonly used tenon connections in ancient wooden structure which are adopted in modern steel-tube supporting systems which is officially called full-hall formwork support system with Mortise and Tenon Joints). Full-hall formwork support system with Mortise and Tenon Joints currently has not yet been used for engineering application on domestic construction site, there is no related experimental research yet. With the advantage of faster and user-friendly construction operation, longer working life, finer applicability, higher overall stiffness, higher bearing capacity, it seems that this new type of supporting system can be widely used for construction purpose and the purpose of widely being used on construction site needs full-scale tests to determine overall bearing capacity and joints tests to guarantee the reliability of tenon connections made of steel. To study the overall bearing capacity of this full-hall formwork support system with Mortise and Tenon Joints, this paper mainly dealt with the following task:(1) Conducted experimental tests to determine the overall bearing capacity of 11 full-hall formwork support system with Mortise and Tenon Joints and quantitatively analyzed the influence of pole spacing and bar-step's influence on the new type support system's ultimate bearing capacity with or without X-bracing and analyzed the X-bracing's effect on the new type support system's ultimate bearing capacity.(2) Analyzed the displacement variation of each measuring point according to the load variation and the This displacement results illustrate this new type support system with tenon joint's buckling mode and used the displacement variation identified finite element computing model's boundary conditions.(3) Adopted the semi-rigidness theory and created 11 FEM model for this new type support system with tenon joints and also used the nonlinear post-buckling analysis method to gain the overall ultimate bearing capacity and the displacement variation of each measuring point according to the load variation; The FEM model's predicted bearing capacity were very close to the experimental tests which verified the FEM model's Rationality and applicability.(4) Experimental tests were conducted to verify the reliability of tenon joint, including semi-rigid test, shearing test, bending and shearing test and tensile test, the test results have verified the reliability of tenon joints.(5) Consider the establishment of an inter-dimensional Designed 3D solid model of this new type tenon joints with the consideration of behavior normal to the surfaces and frictional forces between surfaces(contact analysis) which could accurately reflect the actual working conditions of tenon joints; The consistency of simulation results with experimental tests further validated the rationality and reliability of new type tenon joints.The study of the above aspects including experimental research and finite element analysis, thus the conclusion from this paper could give guidance for the writing of company or industry specifications of full-hall formwork support system with Mortise and Tenon Joints and could also guide the application of the new support system on construction site.