Experimental Study On Shear Performance Of High-strength Ceramic Concrete Frame Mid-joints

Concrete materials are the most widely used contemporary construction materials in the Civil engineering industry. With the development of science and technology and the incessant consumption of resources by human beings,countries continue to advocate using building materials with more green environmental protection,energy conservation and emissions reduction.Therefore,in the near future,low-carbon green buildings will be the mainstream in today’s society construction.And lightweight aggregate concrete as a kind of green environmental protection and energy saving materials has become a hot research topic in the field of modern architecture. But at the same time, lightweight aggregate concrete itself has some disadvantages of low elastic modulus and being prone to brittle failure, etc, thus to some extent, those disadvantages limit the application of the lightweight aggregate concrete in mechanical components, so the study of structures of lightweight aggregate concrete is particularly important.Six test pieces of frame mid-joint are tested by loading in low cycle and repeatedly and studied in the aspect of shear performance in this paper.among them,there are five test pieces are joints of the high-strength aggregate concrete and one is that of ordinary aggregate concrete variable parameters of the test them are axial compression ratio of end-column and the core areas’ stirrup ratio of joints.Through studying the failure modes,hysteresis rules, skeleton curve characteristics,ductility, energy dissipation, strength degradation and stiffness degradation and other issues of mid-joints of the high-strength aggregate concrete in different the core areas’ stirrup ratio and axial compression ratio,which will provide a scientific and effective basis for engineering application of lightweight aggregate concrete. The experimental results showed that fracture pattern of the ceramsite concrete joint is similar to that of common concrete;When axial compression ratio is the same,and stirrup ratio is less than 1.5%, for the ceramsite concrete with high axial compression ratio,its bearing capacity,the ductility and energy dissipation capacity are improved compared withthat with low axial compression ratio,but its strength and stiffness degradation slow down. When stirrup ratio is the same,and axial compression ratio is less than 0.3,for the ceramsite concrete with high stirrup ratio, the ductility of ceramsite concrete frame joints gets low compared with that with low stirrup ratio,its bearing capacity and energy dissipation ability improve,but its the strength and stiffness degradation slow down; Appropriate increase of axial compression ratio and stirrup ratio can enhance shear bearing capacity of the mid-joints in ceramsite concrete frame. Under the same conditions,the shear performance of joints of high-strength aggregate concrete is slightly lower than that of ordinary concrete node.At the end of the paper, it provides some recommendations for the calculation formula of the joints shear capacity of lightweight aggregate concrete,based on the calculation formula of the joints shear capacity of lightweight aggregate concrete advised on Lightweight Aggregate Structure Design Procedures.