Mechanical Analysis And Experimental Study Of Laminated Bamboo-Steel Bolt Connection

The morden glued bamboo has been widely used as engineering material. The reseach group put forward the new super large steel-cable-bamboo combined silo, and the laminated bamboo is introduced as the silo wall. The connection between bamboo and steel frame is a key point for the new silo. As a common used connection, bolt connection has been used widely with the traits of simple, safe and reliable, easy to use and so on. The bolt connection is used to connect bamboo silo wall and silo frame. However, there was little report on the laminated bamboo-steel bolt connection. It is important to research the bearing capacity of the connection.The laminated bamboo is a typical orthotropic material, and the corresponding twelve elastic constants, three compressive strength values and three shear strength values were tested and corrected. The single bolt connection and multi-bolt connection experiments were conducted, and the typical failure modes were summaried. The factors of end distance, bolt diameter, row space, and bolt arrangement were studied. Bisides, the suitability of domestic and foreign formulas for wooden bolt connection were verified. Finally, the finite element simulations for single and double bolt connections were conducted with ABAQUS. Acoording to finite and experiment results, the failure modes were analysised in detail. The FEA results of bearing capacities and load-displacement curves were compared with the experiment results.The following conclusions can be drawn by the research:(1) The laminated bamboo is an orthotropic material, and the corresponding twelve elastic constants, three compressive strengths and three shear strengths were obtained. Laminated bamboo has high mechanical strength and stability, which satisfies the mechanical strength requirements of structural material.(2) When the end distance is no less than five times bolt diameter, the bearing capacities of bolt connections won't significantly increase while the end distance largen.(3) When the row space is no less than five times bolt diameter, the bearing capacities of bolt connetions won't significantly increase while the row space largen.(4) The results of standard test method for evaluation dowel-bearing strength of wood and wood-based products, which uses 5% bolt diameter offset to define yield loads, are reasonable. The results of Chinese and American national design specifications for wood construction are much less than the actual capacities of laminated bamboo bolt connections.(5) The bearing capacities and load- displacement curves of finite element simulation are in line with corresponding experiment results, which verifies the Hill's yield criterion is suitable for laminated bamboo and the finite element models established are valid and correct to simulate the bamboo bolt connections.This work is supported by the Fundamental Research Funds for the Central Universities(NS2015006). The support is greatly acknowledged.