活性粉末混凝土中带肋钢筋搭接性能试验研究#br#

为明确活性粉末混凝土RPC（reactive powder concrete）中带肋钢筋搭接连接的受力性能，合理确定RPC中纵筋的搭接长度，以纵筋搭接长度、RPC强度、搭接钢筋净距和配箍率为试验参数，对39个RPC中的钢筋搭接连接试件进行对拉试验，获得各试验参数对RPC中带肋钢筋搭接连接性能的影响规律。结果表明：对拉荷载作用下，RPC中带肋钢筋搭接连接分别出现钢筋拔出和拉断两种破坏模式，对于保护层厚度小于2倍钢筋直径的拔出破坏试件，一般还伴随外围RPC劈裂裂缝的出现；对于拔出破坏试件，搭接区域的搭接强度随搭接长度增大而略有减小、随RPC强度和配箍率的增加而增大；相较于搭接长度为100mm的试件，搭接长度为150mm试件的搭接强度约减小5%；强度等级为100MPa、120MPa和150MPa的RPC与直径为20mm带肋钢筋间的搭接强度分别约为17.5MPa、19.5MPa和21.1MPa；相较于未配箍筋试件，配箍率为0.34%和0.75%试件的搭接强度分别提高7.8%和13.1%；相较于钢筋净距为20mm试件，净距为0和40mm试件的搭接强度分别约减小5%和8%，但净距40mm试件搭接强度的降低主要是由于试件RPC保护层厚度过小，使得钢筋外围RPC产生劈裂所致。根据试验结果，建立搭接区域钢筋表面搭接强度及临界搭接长度的计算公式，并以该文及其他研究者的试验结果验证了所提公式的适用性，据此可确定带肋钢筋在RPC中的临界搭接长度。

Experimental study on performance of lap-spliced ribbed steel bars in#br# reactive powder concrete

In order to investigate the mechanical behavior of lap-spliced ribbed steel bars in RPC (reactive powder concrete) and determine the splice length of longitudinal steel bars reasonably, tensile tests were conducted on 39 specimens with lap-spliced ribbed steel bars in RPC and the test parameters include the splice length, RPC strength, clear space between the lap-spliced ribbed steel bars and stirrup ratio. The results show that: two failure modes, namely pullout and tensile fracture of the lap-spliced ribbed steel bars, were found for those specimens. For those specimens with cover thickness less than 2 times of the bar diameter and pullout failure mode, the splitting cracks may also be observed on the side surface of the RPC block. For those specimens with pullout failure mode, the splicing strength of the lap-spliced bars decreases slightly with the increase of the splice length, and increases with the increase of RPC strength and stirrup ratio. Compared with that of the specimen with splice length of 100mm, the splicing strength of the specimen with splice length of 150mm decreases about 5%; the splicing strength of lap-spliced ribbed steel bar of 20mm diameter in the RPC of 100MPa, 120MPa and 150MPa, are 17.5MPa, 19.5MPa and 21.1MPa,respectively; and the splicing strengths of the specimens with stirrup ratio of 0.34% and 0.75% increase by 7.8% and 13.1% respectively compared with that of the specimen without any stirrup; compared with the splicing strength of the specimens with clear space of 20mm between lap-spliced bars, the splicing strength may decrease about 7.8% and 13.1%, separately, for those specimens with clear space of 0 and 40mm. The equations of predicting the average splicing strength and the critical splice length of the lap-spliced bars were established based on the test results, and their feasibility was verified by the test results from the third party.