Study On Axial Compression Performance Of Bamboo-phosphogypsum Composite Wall

In this thesis,a new type of bamboo-phosphogypsum composite wall was proposed based on the application requirements and material properties of bamboo and phosphogypsum.The composite wall was mainly composed of original bamboo tubes,cast-in-place phosphogypsum filling layer,oriented strand boards and swallowtail nails.It was economical and environmental friendly with advantages of heat and fire prevention,heat and sound insulation,and excellent axial load bearing capacity to meet the needs of green buildings development.Firstly,this thesis studied the basic mechanical properties of bamboo and phosphogypsum,and summarized failure modes of parallel-to-grain tensile and compressive specimens of bamboo,and the failure modes of axial compressive and splitting tensile specimens of phosphogypsum.The parallel-to-grain tensile strength and elastic modulus,the compressive strength and elastic modulus of bamboo,and the axial compressive strength,splitting tensile strength,compressive strength,tensile elastic modulus and Poisson’s ratio of cast-in-place phosphogypsum were obtained from experienments.Secondly,this thesis tested four full-length walls.The detailed production process,assembly steps and test methods of wall specimens were introduced systematically.The failure modes of four wall specimens were summarized.The influences of oriented strand boards and the number of bamboo tubes on the axial bearing capacity of composite walls were analyzed.The strain variation of measuring points of wall specimens was also analyzed.The results show that the failure modes of four composite walls were similar.The top side of composite wall was taperedly crushed,and the top side of the bamboo tube was splitting failure.The oriented strand board has no significant effect on the axial bearing capacity of the composite wall,while the increase of bamboo tubes can improve the wall stiffness and axial bearing capacity.The bamboo-phosphogypsum composite wall has excellent cooperating performance according to similar strain variation value of measuring points on bamboo and phosphogypsum.Finally,the finite element model of bamboo-phosphogypsum composite wall was constructed in Abaqus software,and the accuracy of the model and the correctness of the simulation method were verified by combining the experimental phenomenon and results.Based on reasonable finite element model construction method,variable parameter analysises were carried out on the thickness of cast-in-place phosphogypsum filling layer,the thickness of bamboo tube walls and the diameter of bamboo tube,the distance of adjacent bamboo tubes,the height of composite wall,the thickness of protective layer of bearing surface,and the bamboo tube filled with phosphogypsum.The results show that the axial compression capacity of the composite wall model enhances with the increase of the thickness of cast-in-place phosphogypsum filling layer,the thickness of the bamboo tube walls and the diameter of the bamboo tube.The set of bearing surface of protection layer and the decrease of distance between bamboo tubes and the height of composite wall can improve the bearing capacity of axial compression.The stiffness and ultimate bearing capacity of composite wall can be improved by filling bamboo tubes with phosphogypsum.