Study On Test Method Of Shear Performance Of Direct Shear Anchor Bolts

Nowadays,Post-Anchorage technology is very popular in the reinforcement industry in China,and has become one of the commonly used reinforcement technologies.At present,a lot of achievements have been made on this technology at home and abroad.These studies are all carried out by the anchor steel plate reinforcement method.From these results,the anchor steel plate reinforcement method can greatly improve the bearing capacity of members,and also limit the development of cracks in members.But there are also some problems in the anchor steel plate method.For example,the specification of our country stipulates that the full-thread form of anchor bolt should be adopted in this technology.Although this form can increase the bonding effect between the bolt and the anchor glue and the base material concrete,it will inevitably reduce the bearing capacity of the bolt.Therefore,it is necessary to discuss whether this regulation is applicable to the shear of anchor bolt or not.The bolt reinforcement method can't make each bolt work together because of the construction technology problems,and it will certainly reduce the ultimate bearing capacity of the bolt.Although domestic and foreign research has made detailed reasons for its occurrence,there are very few new ideas to avoid this problem,or even if the new method is put forward,it still has little effect after use.Finally,the traditional anchor shear test device can not avoid the shear warping effect of loading plate,which can not well meet the actual situation of the project.In this paper,the above three problems are discussed.Firstly,a new single-anchor loading device is developed,which is to increase the tension-assisted anchor bolt in the single-anchor shear test and inhibit the steel plate from lifting.It is called double-anchor shear test method.Then,C30 concrete base plate was selected to carry out single anchor test for six groups of semi-threaded bolts and six groups of full-threaded bolts.According to the failure modes and load-displacement curves of the two groups,it is concluded that semi-threaded bolts are suitable for bolts under shear loads.Finally,in the summary of the predecessors,our team developed the technology of direct shear type steel plate technology,and carried out five groups of ordinary double anchors,five groups of ordinary three anchors,five groups of ordinary four anchors,five groups of direct shear double anchors,five groups of direct shear three anchors and five groups of direct shear four anchors.By comparing with ordinary anchor bolt,the direct shear anchor bolt technology can greatly improve the stiffness,carrying capacity and ductility of components.It is concluded that the direct shear anchor bolt has better performance,which provides experimental basis for popularizing the technology of direct shear profiled steel sheet.In addition,ABAQUS finite element analysis of single anchor,direct shear double anchors,direct shear three anchors and direct shear four anchors is carried out in this paper.Reasonable agreements can be seen between the shear-displacement curves from the test and finite element analysis.This paper innovation point:(1)The loading device in this paper is developed by our team independently.Compared with the traditional loading device,it has the advantages of easy promotion and simple operation.(2)The single anchor test in this paper is carried out by the double anchor shear test method developed by our team independently.It solves the problem of steel plate heave when single anchor is used by auxiliary anchor bolt,and the results are closer to the actual engineering anchor bolt state.(3)For the first time,the direct shear anchor group anchor is comprehensively analyzed.The direct shear double anchor is compared with the ordinary double anchor,the direct shear three anchor with the ordinary three anchor,the direct shear four anchor with the ordinary four anchor,and the direct shear anchors group has better performance than the ordinary anchors group.