Experimental Study On Mechanical Properties Of Post-anchored Adhesive Bonded Anchors For Lightweight Concrete

Adhesive bonded anchors have the advantages of low temperature resistance,heat resistance and easy installation,and have been widely used in normal concrete.The anchorage performance in lightweight concrete is still unclear,which restricts the application of this type of anchors.In order to study the tensile performance,shear performance and tensile and shear combined loading performance of adhesive anchors,static loading tests were conducted to analyze the influence of anchor diameter,anchorage depth and other factors on the ultimate load of adhesive anchors,and the specific work and results are as follows.(1)For the constrained tensile performance of adhesive bonded anchors in lightweight concrete,39 specimens were designed for the constrained tensile tests.By analyzing the ultimate load and failure mode,the effects of concrete type,bonded anchor type,bonded anchor diameter and anchorage depth on the constrained tensile performance were obtained,and a multivariate nonlinear regression analysis was performed on the test results to give the design formula for the constrained tensile load applicable to lightweight concrete.The results of the study show that there are two types of failure modes of bonded anchor specimens under the constrained tensile conditions: pull out failure and anchor steel failure,in which the adhesive-cone interface failure occurs in through-wire bonded anchor specimens and the adhesive-steel interface failure in inverted cone bonded anchor specimens.The analysis shows that the bond strength decreases with the increase of bonded anchor diameter and increases with the increase of anchorage depth.(2)For the unconstrained tensile performance of bonded anchors in lightweight concrete,42 specimens were designed for unconstrained tensile tests.The effects of concrete type,bonded anchor type,bonded anchor diameter and anchorage depth on the ultimate tensile load and failure mode were studied.The test results were analyzed against the codes of different countries,and the formulae for calculating unconstrained tensile load of bonded anchors applicable to the lightweight concrete were obtained by multiple non-linear regression and failure mode combination analysis.The results show that concrete cone failure and combined cone failure occurred mostly in the specimens.The tensile load of the specimens increased with the increase of anchorage depth,and the failure mode changed from concrete cone failure to combined cone failure and splitting failure.(3)For the shear performance of bonded anchors in lightweight concrete,48 specimens were designed for shear tests.The effect of concrete type,bonded anchor type,bonded anchor diameter and anchorage depth on the shear load was studied,and the test results were analyzed against the codes of various countries to obtain the formula for calculating the shear load of bonded anchors applicable to lightweight concrete.The results show that: under the shear test,more occurring anchor steel failure.The shear load of anchor steel failure increases significantly with the increase of diameter,and is not related to the anchorage depth,concrete type and other factors.(4)For the tensile and shear combined loading performance of bonded anchors in lightweight concrete,20 specimens were designed for the tensile and shear combined loading test.The effect of concrete type,bonded anchor diameter,anchorage depth and tensile-shear ratio(the ratio of tensile load to shear load)on the tensile and shear combined loading performance was analyzed,and after comparing the test results with the calculation results of the specification formula,a multivariate nonlinear regression was performed on the test data to obtain the design formula for the design value of the load under the tensile and shear combined loading conditions applicable to lightweight concrete.The results show that the specimens are subjected to tensile failure.The ultimate load in both normal concrete and lightweight concrete increased with the increase of anchorage depth and decreased with the increase of tensile-shear ratio,and the change of tensile-shear ratio had no significant effect on the tensile force on the anchors.