## 1 Introduction  
Tubular structure has been widely used in many buildings such as railway stations, stadiums, airports, bridges, jack-up offshore platforms, coal sheds and farm buildings due to its high bearing capacity and low weight [1]. Generally, a tubular structure is constructed by connecting different hollow section members. Therefore, connection between different hollow section members is crucial. The thickness of hollow section members used in heavy-load tubular structures is relatively thick, and thus, they are frequently welded together directly in reality. However, for light-steel tubular structures, thickness of the hollow section members is generally in between 0.6 and 2 mm, and thus, it is not preferred to use welding to connect them due to welding defects that frequently occur, such as welding penetration. Besides, welding is very time consuming and also requires high welding skill. Traditionally, screws, rivets and bolts are preferred to connect thin-walled steel sections used in light-steel structures [2; 3; 4; 5; 6; 7] and the ultimate bearing capacity of the connection is one of the main concerns in engineering practice. Many researchers have studied the bearing capacity, joint stiffness and failure mode of different connections of light-steel structures. For instance, [PERSON] and [PERSON] [8] investigated the joint stiffness of bolted single-lap joints and cold-formed steel (CFS)trusses by conducting tests. They also proposed a theoretical model for predicting joint stiffness. [PERSON] and [PERSON] [9] carried out tests and numerical analyses on a full-scale apex connection of CFS frames. The apex connection was fabricated by connecting two CFS back-to-back double sigma rafter sections using a gusset apex plate and bolts. Similarly, [PERSON] et al. [10] investigated the mechanical behavior of the eaves joint of CFS portal frames by carrying out finite element analyses (FEA). The eaves joint consisted of channel sections, screws and bolts. [PERSON] et al. [11] investigated the shear stiffness of thin-walled cold-formed storage rack frames by carrying out experiments and numerical analyses. Channel sections of storage rack frames were connected using bolts. [PERSON] et al. [4] carried out a comparative study on the mechanical behavior and construction characteristics of 96 CFS lap shear tests, including four types of connection using the self-piercing rivet, clinching, self-drilling screw and blind rivet, respectively. [PERSON] et al. [12] investigated the flexural behavior of CFS trusses assembled by using self-piercing rivets. [PERSON] et al. [13] also carried out experimental tests to investigate the structural behavior of CFS truss composite floors in which the truss is assembled using self-piercing rivets. Similarly, [PERSON] et al. [14] carried out cyclic loading tests on CFS truss composite floors. The steel truss consisted of C-shaped steel sections connected by self-drilling screws. [PERSON] et al. [15] carried out tests and FEA to investigate the effect of deployment patterns of self-drilling screws on the bearing capacity of high-strength CFS joints. [PERSON] et al. [16] investigated the bearing capacity of five CFS connections assembled using two types of gusset plates and self-tapping screws. [PERSON] et al. [17] conducted static and cyclic loading tests to investigate the failure mechanism and structural behavior of 26 CFS trusses. The CFS truss specimens were assembled by connecting C-shaped steel sections using a novel developed Howick rivet connector (HRC). [PERSON] et al. [18] experimentally investigated the strength and stiffness of floor trusses consisting of CFS lipped channels. [PERSON] et al. [19] investigated the bimoment effects on the load transfer in CFS bolted moment connections. The lipped channel chord and braces of the CFS trusses were connected using bolts. [PERSON] et al. [20] conducted static loading tests on five CFS joints with positive eccentricity. The chord of the five CFS joints was hat section and was connected with the C-shaped braces using bolts.