Experimental research on pullout performance of prestressed threaded steel bar with anchor plate

LIU Junli; PEI Tianshi; AN Yongchang; LIANG Tao; CHEN Jun; ZHENG Yan

doi:10.16186/j.cnki.1673-9787.2023040001

Abstract：Objectives In order to investigate the anchoring performance of prestressed threaded steel bars with a diameter of 25 mm and a strength grade of PSB1080 when pulled out from reinforced concrete thick slabs or foundations with effective anchorage lengths of 150,200,250 mm,Methods experiments were conducted on 7 specimens with parameters including effective anchorage length,presence of sleeve,width of anchor plate,and number of structural rebars.The failure characteristics of the specimens were studied,and the load-displacement curve,ultimate pull-out capacity,crack load of the specimens,and load-strain curve were analyzed.Results The pull-out capacity of the specimens increased with the increase of anchorage length,and when the effective anchorage length was 250 mm,all prestressed threaded steel bars could yield;the crack load of concrete in-creased with the increase of effective anchorage length,width of anchor plates,and the addition of a sleeve,and the influence of the number of structural rebars on the crack load of surface concrete was not significant;the crack load of surface concrete specimens with a sleeve was 2.66 times higher than that without a sleeve;ac-cording to the load-displacement curve,it can be seen that adding structural rebars on the anchor plate can pre-vent the phenomenon of a sharp decrease in load capacity when prestressed threaded steel bars with anchor plates are pulled out;based on the test results and relevant literature,the experimental values of specimens with anchor zone concrete cone failure were compared with the calculated values,Nilforoush's proposed formula and the Japanese JSCE specification formula 9.2.11,which were respectively 19%and 10%lower than the ex-perimental values.Conclusions Adding a sleeve can effectively increase the crack load;using Japanese JSCE specification formula 9.2.11 to calculate the pull-out capacity is closer to the experimental values.