The Experimental Research On Shear Behavior Of The Groove Interface With Rebar Between New And Existing Concrete (C30)

The augmented section method and the additional prestressing method have become a common way of strengthening concrete structure. The shear resistance of the new and existing concrete interface is the key for the success of the two methods. The shear resistance of the new and existing concrete interface can be improved by cutting groove and implanting rebar on the interface. But it is a lack of research at home and abroad, and there’s no relevant design specification in our country, so it is significant to study the shear behavior of groove interface with rebar between new and existing concrete.Interface processing, groove size and steel ratio are set as test parameters in this paper. 18 specimens with different parameters are made and tested. The influence of different test parameters on shear behavior of the new and existing concrete interface is studied by cracking load, residual load, ultimate strength, slippage, transverse displacement and failure mode of the specimens. Achievements have been made as followings.(1) In this paper, the reasons for the weakness of the new and existing concrete interface are analyzed, the influence factors on the bonding property of the new and existing concrete interface are summarized. Based on the bonding model, the bonding mechanism of the new and existing concrete interface is analyzed under the condition of both implanting rebar and without implanting rebar.(2) Test results show that the cracking load of the new and existing concrete interface can be improved by cutting groove, increasing the width of the groove and increasing the ratio of implanting rebar on the new and existing concrete interface. The residual load of the new and existing concrete with rebar increased with increasing the steel ratio, cutting groove on the new and existing concrete interface with rebar can also improve the residual load while the width of the groove has less influence on it.(3) According to the shear load-vertical slip curves and the shear load-horizontal slip curves of the new and existing concrete specimens, the monolithic specimens and the surface roughening specimens without rebar failed brittlely while the specimens with rebar failed ductilely. The specimens with rebar can still withstand loads and maintain integrity while the vertical relative slip approach 4 mm.(4) The shear capacity formula in the specification of ACI 318-14 and AASHTO LRFD 2014 and presented by the domestic and foreign scholar in the literatures are summarized in this paper. The result of the test is compared with the result calculated by formulae. It can provide guidance to the concrete structure strengthening engineering.