Experimental evaluation of coupler behavior for mechanical rebar splices in reinforced concrete structures

Abstract

The use of mechanical splices to connect steel bars is an important solution in many infrastructure projects worldwide. In Brazil, this system is rarely used. The Brazilian standards regarding this subject are old and out of date; particularly with regard to the performance evaluation test methods for these splices in the laboratory. This paper presents and discusses the test procedure proposed in the international standard ISO 15835 [1] in light of the current procedure defined by Brazilian Standard ABNT NBR 8548 [2], applied to types of mechanical splices commonly used in Brazil: taper threaded and bolted couplers. Performance parameters for these mechanical splicing systems related to structural integrity in reinforced concrete structures are evaluated on the basis of the results obtained in these tests. In the end, it is intended that this paper provide support for discussion of design procedures and laboratory performance evaluation of couplers for mechanical splices of steel bars in reinforced concrete structures in future reviews of Brazilian standard ABNT NBR 8548 [2].

Optimizing Rebar Consumption and Cutting Waste in Column Reinforcement: Integrated Mechanical Couplers and a Special-Length-Priority Minimization Algorithm

“…Although conventional lap splicing has long been considered a reliable and effective method for rebar splicing, it has several drawbacks that limit its applicability. These drawbacks include increased rebar consumption and waste, rebar congestion, a higher cost, and unsuitable use in the plastic hinge region [4,10,11,15]. Moreover, several studies [12,15,29] have highlighted that the adoption of lap splices may lead to the over-reinforcement of the section, reduced ductility, and ultimately a change in the structure's deformation capacity.…”

“…This discovery provides valuable knowledge regarding the behavior and applicability of couplers in RC structures. Furthermore, previous studies have reported several benefits of mechanical couplers [4,11,15]: (1) alleviating rebar congestion problems;…”

“…A variety of couplers are commercially accessible and available on the market, namely, (1) shear screw couplers [31,32], (2) grouted sleeve couplers [31,32], (3) parallel threaded couplers [4,31,32], (4) swaged couplers [4,31,32], and (5) rib-thread couplers [4,31,32], as illustrated in Figure 1. Threaded couplers are the most prevalent type of coupler, characterized by their short length and ease of installation [14,33].…”

“…Conventional lap splicing with confining reinforcement, commonly used to connect adjacent rebars for decades [3,4], is one of the major contributors to waste and carbon emission issues in the industry. Lap splices necessitate longer lapping lengths, especially for larger-diameter rebars in high-rise buildings, and they have to be positioned following building codes, which augment rebar consumption and waste.…”

“…In addition, the application of conventional lap splicing has several drawbacks, including rebar congestion, increased rebar waste, higher costs, and impaired structural integrity [4,[10][11][12][13][14][15]. The emergence of mechanical splices or couplers sheds light on this issue.…”