Yiyi Chen

Effect of loading protocols on the hysteresis behaviour of hot-rolled structural steel with yield strength up to 420 MPa

This paper presents a series of material tests on hot-rolled structural steel with nominal yield strength ranging from 235 MPa to 420 MPa to study the effect of loading protocols, material thickness and yield strength on the hysteresis behaviour. A total of seven tensile coupon tests were conducted and a total of twenty one experiments were conducted in cyclic axial configuration on hot-rolled structural steel. Three different cyclic loading protocols were adopted namely, Cyclic Ascend, Cyclic Alternate and Cyclic Tensile with strain amplitudes varying between +/–0.5% to +/–2%. The results of the hysteretic responses at different loading protocols were presented and compared. The results revealed the non-masing and accumulated strain-hardening behaviour of the tested materials and the effect of material thickness and yield strength on the characteristics of hysteretic response was minimal. The loading protocols affect the hysteresis behaviour but are insignificant for seismic applications within the range of the strain in the tests.

Seismic performance of floor-by-floor assembled steel braced structures with stiffened connections

This paper presents an overview of a full-scale testing on a tension-only concentrically braced beam-through frame (TCBBF). The implementation of TCBBF facilitates the construction of low-rise industrialised residential steel houses by means of floor-by-floor assembling. This type of TCBBF system features cold-formed hollow structural section columns connected to H-section through beams by end plate with bearing-type high-strength bolts. A two-storey, four-span by one-span TCBBF subjected to vertical loads was cyclically loaded horizontally to examine the seismic behaviour. Stable behaviour was observed up to a storey drift angle of 1/10. The cyclic behaviour was characterised by a linear response, a slip range and a significant hardening response. Deteriorating pinched hysteretic behaviour was notable for cyclic loading primarily because of cyclic brace compression buckling and tension yielding. TCBBF incorporates very slender bracing members that are unable to bear much axial load when subjected to compression. Alternating brace compression buckling and tension yielding induce unrecoverable plastic deformation, which results in a sharp decrease in the lateral system stiffness of TCBBF when lateral displacement becomes zero or around zero. Additionally, bracing members and frame members share different proportions of horizontal force although the dual systems bear the lateral forces collaboratively. The variation philosophy of distribution proportion of bracing and frame members is evaluated. Pushover analysis is undertaken to duplicate the test results and develop an analytical model, which is able to predict the elastic stiffness and the strength reasonably.

Overall investigation of affordable residential housing in China

Affordable housing is a key item identified in the world for the development of the 21st Century. The object of this paper is to get series of design concepts of affordable residential houses, using intensive steel solutions, in key geographical areas of China. Detailed Social-Geographical-Economic conditions, residential housing situation, including housing market as well as some traditional housing concept, and intensive steel residential building solutions in China are fully investigated. Based on these investigations, the affordable house suitable for China can be defined as a green humanized multi-storey house system comprised of medium-small-type dwellings whose cost is not higher than that of traditional reinforced concrete buildings. This definition could be the guiding ideology of the future residential housing design.

Three-Dimensional Cyclic Performance on New Ring-Beam Connection between Concrete-Filled Tubular Column and Reinforced-Concrete Beams

This paper introduces a new type of connection between concrete-filled steel tubular (CFST) column and reinforced concrete (RC) beam through a transitional RC ring beam encircling the CFST column. Four scaled specimens, representing an interior-column joint, were tested under bi-directional cyclic loads to examine the seismic performance and the influence of the reinforcement on the joint. Load-deformation response, failure mode, strain distribution, and energy dissipative performance were presented. Test results indicated ductile performance and the multi-directional nature of the force system in the ring beam. Finite element models were also calibrated against test results and results from parametric analysis confirmed the effect of tube diameter and longitudinal reinforcement in the ring beam on the structural performance.