Research On Joint Quality Detection Technology Of Assembled Concrete Double Deck Shear Wall Structure

In recent years,China advocates green construction,and the development of prefabricated building has become the mainstream.As a new fabricated shear wall,the double-sided laminated shear wall is composed of two layers of prefabricated slabs and truss steel bars.The vertical connecting steel bars are inserted into the cavity between the prefabricated slabs,and then concrete is poured to connect and fix the walls,one part of the vertical connecting steel bars is embedded in the concrete of the lower member,and the other part is exposed,until the upper shear wall is connected with the lower shear wall to form a whole.Therefore,the quality of the steel bar connection directly affects the bearing capacity and seismic performance of the double-sided laminated shear wall structure,but the vertical connecting steel bar is temporarily inserted and fixed in the construction site,in the process of on-site construction,various complex working conditions and human factors will lead to insufficient anchorage length or large spacing of the steel bar,which seriously affects the structural safety;The middle layer of the double-sided laminated shear wall is post-poured concrete,as a secondary molded product,there will be a new and old concrete interface between the precast layer and the post-poured layer,and the bonding quality of the interface will also affect the mechanical performance of the double-sided laminated shear wall;Because the upper and lower members are wrapped by the post cast concrete of the middle layer to achieve the force transfer effect,the middle layer is not easy to form Whether the post cast concrete is dense or not will also affect the connection performance.But there is no complete technical standard for testing,and there is no effective technical support for the above problems.In order to ensure that the connection quality of the double-sided laminated shear wall meets the design requirements,this thesis conducts testing and research on the connection quality of the vertical connecting steel bars,the bonding quality of the new and old concrete joints,and the density of the post-cast concrete,and proposes corresponding detection methods and precautions.The specific work is as follows:(1)For the inspection of the connection quality of the vertical connecting steel bars in the double-sided laminated shear wall,three double-sided laminated shear wall specimens were designed and fabricated,the X-ray in vitro reference object method was proposed,and the empirical formula was derived,and used this method to test and verify the length and spacing of the vertical steel bars between the layers inside the test piece,and the test results have a smaller error compared with the preset working conditions.At the same time,the radar method is used to determine the length and spacing of the vertical connecting steel bars inside the test piece,the detection results are compared with the preset working conditions,and the error is also small;By comparing the two detection methods,the X-ray detection image is clearer,the detection accuracy is higher,the radar signal is easy to be interfered,and the misjudgment or missed judgment phenomenon is easy to appear in the image recognition.(2)For the detection of the bonding quality of the new and old concrete joint surfaces of the double-sided laminated shear wall,the ultrasonic method is used to detect the defects of the joint surface,and the drill core planting bar drawing method is used to detect the bonding strength of the joint surface.The test results show that the ultrasonic method can accurately measure the position of the defect at the joint surface,and the inspection image is clear.The drilling core planting bar drawing method can detect the bonding strength of the joint surface,indicating that the joint surface is the weak part of the laminated component.It is suggested that the method of planting bars in the middle post pouring layer should be used to detect the bonding strength of the joint surface.(3)For the detection of the density of post-poured concrete of the double-sided laminated shear wall,ultrasonic method,X-ray method and radar method were used to detect the density of post-poured concrete.The test results show that the three methods can detect the density of post-poured concrete.Ultrasonic method can display its position and depth through imaging,X-ray method can clearly capture the size of the defect,radar method can also detect the signal of the defect,but the radar signal of the defect is susceptible to interference,and it will be misjudged or missed during recognition,it is necessary to further study the applicability of radar method to detect the defects of post-poured concrete.