Study On Lapping Connection Performance Of Constrain-anchorage Reinforcement In Shale Ceramsite Concrete

Precast concrete structure is one of the most important kinds of building industrialization,which has many advantages such as improved quality,shortened construction period,saving energy,reducing consumption and cleaned production.Assembling structure made with components of lightweight and high-strength could has less weight and convenience of transportation and installation.Otherwise,it meets the requirement of building energy efficiency and seismic design.Shale ceramsite concrete is one of the development direction of prefabricated concrete structure building under the building industrialization,depending on its wide use in prefabricated concrete structure and the mechanical properties of lightweight,high-strength and heat preservation.This paper studies the connection performance and its main affected parameters of the lap joint of shale ceramsite concrete constraint anchorage.Rebar connection forms and their scope of application,the advantages and disadvantages,as well as the bond mechanism between reinforcement and concrete and current studying of constraint anchorage were thought.And 45 lap joints of shale ceramsite concrete constraint anchorage were designed.4 affected parameters that the strength of shale ceramsite concrete,lap length,arrangement of spiral reinforcement and volume stirrup rate were chosed to analyzing.According to the performance grade of reinforcement joint from 《Technical specification for mechanical splicing of steel reinforcing bars》(JGJ 107-2010),three kinds of experiments including single tensile test,repeated high pressure tensile and compression test and repeated large deformation tensile and compression test were designed.Compared the result of same lap length shale ceramisite concrete specimens with different strength,the connection performance of shale ceramisite concrete constraint anchorage would be better with the higher strength of shale ceramisite concrete.lap length of the specimens named LC30、LC40、LC50 could be reduced at least 0.7laE by contrastive analysis.The failure form of the specimens with shorter lap length is splitting failure.Splitting cracks of several specimens with 0.5laE lap length are connected two ends of the surface.Soon after the reinforcement yield,the width of lengthways splitting cracks approach the specification limits.Before the reinforcement yield,the constraint from double spiral stirrups were improved with the higher volume stirrup rate.The specimens made with double spiral stirrups and others with single spiral stirrups have same connection strength and failure form.The constraint of double spiral stirrups is reliable when used in the reinforcement connection in the shale ceramisite concrete.