Mechanical Properties Of The Thin-walled SHCC Pipes Under Compression Using Three Edge Bearing Method

As one of the most developing Fiber Reinforced Concrete,Polyvinyl AlcoholStrain Hardening Cement-based Composites(PVA-SHCC or SHCC for short) is a new type of concrete. By mixing the PVA fibers,flyash,and quartz into cement-based concrete,the toughness of the SHCC could be improved significantly. When bearing the tensile load,SHCC showed the features of multi-cracking and strain hardening. A increasing number of developed countries had used this new material in projects,but there is few research focus on the SHCC pipe. This paper made some research on SHCC pipe based under the support of National 863 Plan(2013AA031306).Focused on problems in the application of the SHCC pipe,this paper analyzed the strain,deflection and cracking behavior of the SHCC pipe under the flat load based on lots of experiments. Furthermore,the ultimate bearing capacity and stiffness of the SHCC pipe have been discussed. The contributions are showed as follows:(1) Based on the uniaxial tensile test and flat crushing test,the failure process of the SHCC could be divided into 4 stages:elastic stage,cracking stage,strengthening stage and failure stage. This paper analyzed the test result of each stage and concluded that:comparing to the common cement-based concrete pipe,the SHCC pipe has the advantages of thiner wall,lighter mass and higher strength.(2) This paper built a new mechanical model for SHCC pipe under the condition of flat crushing. Based on the theories of the maximum compressive strain and maximum moment,the ultimate load bearing capacity of the SHCC has been calculated and analyzed by each theory. Moreover, we discussed the advantages and disadvantages for both theories.(3) The analysis for the stiffness of the SHCC pipe under the conditioni of flat crushing showed: the stiffness of the SHCC pipe was changing from the cracking stage,and with the increasement of the flat crushing load,the changing trend was becoming faster.All contributions proposed in this paper was centred on the SHCC pipe. And,to some extent,the conclusions improved the basic theory of the SHCC and may promote the application of the SHCC pipe.