Mechanical Behavior And Reliability Analysis Of Strength Design Value Of Bamboo Scrimber Under Tension Or Compression

Bamboo scrimber is a kind of bamboo material made by disintegrating the original bamboo into net-like fiber bundles along the length direction,arranging the fiber bundles in parallel,and then drying,dipping,molding,hot pressing or cold pressing.Short-term regeneration,degradable after the abandonment,high utilization rate,strong mechanical properties,excellent seismic effect,strong carbon fixation ability,and factory prefabrication.Compression and tension mechanical properties have been widely studied as important indicators to measure the mechanical properties of bamboo scrimber.At present,the relevant research on the mechanical properties of bamboo scrimber under compression and tension mostly refers to the relevant specifications of Chinese and American wood structure test methods.However,there is no relevant literature to analyze the difference and connection between the mechanical properties of the bamboo scrimber obtained by the two different test methods in China and the United States.In addition,the current design values of compressive and tensile strength of bamboo scrimber mostly adopt the allowable stress design method and limit state design method.Most of the design values based on the analysis of limit state design theory need to be calculated through programming,which does not conducive to engineering popularization and application.Therefore,it is necessary to compare and analyze the compression and tension mechanical performance parameters of the bamboo scrimber obtained by the wood structure test methods of China and the United States,and propose a simple calculation method for the reliability analysis of the design value of the compression and tension strength of the bamboo scrimber.In this paper,with reference to wood structure test specifications of China and the United States,the compression and tensile properties of bamboo scrimber(parallel to grain,perpendicular to grain)have been tested,and the following researches have been carried out:(1)Combined with the trend of the stress-strain curve,the failure modes of the bamboo scrimber under compression and tension are deeply analyzed,and the mechanical performance parameter values of each control stage are extracted;the goodness of fit test is performed on the mechanical performance parameter values of each control stage;The differences and connections between the mechanical properties of the bamboo scrimber obtained by using two different test methods in China and the United States are analyzed in this dissertation.(2)The nonparametric method was used to extract the percentile values of the mechanical properties of the bamboo scrimber specimens under pressure and tension at each control stage,and the compressive and tensile elastic modulus and each control stage of the bamboo scrimber were obtained through linear and nonlinear fitting.The correlation between stress,and the correlation between compressive and tensile strength.(3)Based on the analysis of the failure mode,stress-strain curve trend,and mechanical property parameter values of the bamboo scrimber specimens under compression and tension,a mathematical model of the stress-strain relationship is proposed.The stress-strain models of each compression and tension are fitted.The optimality is analyzed,and the optimal function expressions of the compressive and tensile stress-strain models are proposed.Based on engineering safety and data stability considerations,a 95% guarantee rate of component stress-strain relationship expressions is proposed.(4)Solve the standard values and design values of compressive and tensile strength of bamboo scrimber under parametric and nonparametric methods with reference to the specifications;a simplified probability limit state design method are proposed,and the corresponding design value of the compressive strength parallel to grain are calculated.According to the reliability index,the design value of the compressive strength parallel to grain that does not meet the reliability requirements of the specification was revised;the influence of the different values of the component resistance coefficient and the continuous load effect coefficient on the design value of the compressive parallel to grain are analyzed.