رفتار سازه اتصالات پیچی فولاد ضد زنگ سرد شکل گرفته

This paper presents a series of tests on cold-formed stainless steel bolted connections. The test specimens were fabricated from three different types of stainless steel, including austenitic stainless steel EN1.4301 (AISI 304) and EN1.4571 (AISI 316Ti having small amount of titanium) as well as lean duplex stainless steel EN1.4162 (AISI S32101). The material properties of the three types of stainless steel were determined by tensile coupon tests. Stainless steel single shear and double shear bolted connections with different bolt diameter and bolt arrangement were tested. Two main failure modes were observed in the bolted connection tests, namely the bearing and net section tension failures. The test strengths were compared with the nominal strengths calculated using the American Specification, Australian/New Zealand Standard and European codes for stainless steel structures. It is shown that the nominal strengths predicted by these specifications are generally conservative. Furthermore, the failure modes observed from the tests were also compared with the failure modes predicted by the specifications. It is shown that the failure modes predicted by the European codes are more accurate than the American and Australian/New Zealand predictions.

The desirable characteristics of stainless steel, such as attractive appearance, corrosion resistance, better fire resistance as compared to carbon steel, low maintenance and so on, can be exploited in a wide range of construction applications [1] and [2]. A comprehensive discussion of these characteristics and the application of stainless steel in structural design have been reported by Gardner [3]. Bolted connection is one of the common types of connection in cold-formed steel construction. The design rules of stainless steel bolted connections are available in the current design specifications, i.e. the American Specification (ASCE) [4], Australian/New Zealand Standard (AS/NZS) [5] and Eurocode 3 Part 1.4 (EC3-1.4) [6]. However, the design rules in these specifications are mainly based on the rules of carbon steel with small modifications as experimental works of stainless steel bolted connections were relatively limited [7]. Tests of carbon steel bolted connections were conducted by researchers such as Zadanfarrokh [8], Rogers and Hancock [9], [10] and [11] and Chung [12]. The behavior of austenitic stainless steel type EN1.4306 (AISI 304L) bolted connections was investigated by Bouchaïr et al. [13]. It should be noted that experimental investigation on stainless steel bolted connections is limited so far. Furthermore, the stress–strain behavior of stainless steel is fundamentally different from that of carbon steel [3]. Therefore, it is important to investigate the structural behavior of bolted connections of stainless steel. In this study, the connection specimens were fabricated from three different types of stainless steel, including austenitic stainless steel EN1.4301 (AISI 304) and EN1.4571 (AISI 316Ti, containing 0.34% titanium as specified in the STALA Tube mill certificate) as well as lean duplex stainless steel EN1.4162 (AISI S32101). Lean duplex stainless steel is a relatively new material in the family of stainless steel. It is a high strength material having the nominal yield stress (0.2% proof stress) of 450 MPa. The lean duplex material cost is much lower than the duplex material. Up to date, no test has been reported on lean duplex stainless steel bolted connections. It should be noted that the current design specifications do not cover the design of lean duplex. In this study, the material properties of the three types of stainless steel were determined by tensile coupon tests. Stainless steel single shear and double shear bolted connection tests were conducted on the three types of stainless steel by varying the size of bolt, the number of bolt and the arrangement of bolt. The test strengths were compared with the nominal strengths obtained using the ASCE Specification [4], AS/NZS Standard [5] and Eurocodes [6] and [14]. In addition, the failure modes observed from the tests were also compared with the failure modes predicted by these specifications.

An experimental investigation of cold-formed stainless steel bolted connections has been presented. The connection specimens were fabricated from three different types of stainless steel, including austenitic stainless steel EN1.4301 (AISI 304) and EN1.4571 (AISI 316Ti having small amount of titanium) as well as lean duplex stainless steel EN1.4162 (AISI S32101). The tests were carried out under both single shear and double shear bolted connections. The test specimens were designed by varying the size of bolt, the number of bolt and the bolt arrangement. The test strengths were compared with the nominal strengths predicted by the American Specification, Australian/New Zealand Standard and European codes for stainless steel bolted connections. The nominal strengths predicted by the three specifications are generally conservative for both single shear and double shear bolted connections. However, the single shear bolted connections are generally more conservative than the double shear bolted connections predicted by the three specifications. Generally, the nominal strengths predicted by the American and Australian/New Zealand specifications are more conservative than those predicted by the European specifications. The bearing failure and the combined of bearing and net section tension failure were mainly observed from the stainless steel bolted connection tests. The failure modes observed from the tests were also compared with the failure modes predicted by the specifications. It is shown that the failure modes predicted by the European codes are generally agreed with the failure modes observed from the tests. The failure modes predicted by the American and Australian/New Zealand specifications are less accurate than the European codes predictions.