This paper outlines a new approach to structural stainless steel design that is based on exploiting the full deformation capacity of cross-sections, by adopting a continuous method of cross-section classification and member design, coupled with more accurate material modelling. Recently generated laboratory test results are presented, and it is shown how these have been used in combination with existing test data to validate the proposed method. A comparison of the prediction of test results is made for the proposed procedure and the Eurocode approach for square and rectangular hollow section stub columns, beams and pin-ended columns failing by flexural buckling. Average design advantages of around 20-25% are achieved.

     Pretensioned long-span steel space structures are a new type of hybrid structures resulting from combining modern prestressing technology with long-span structures such as space grid structures (including space trusses and lattice shells), cable-bar tensioned structures and spatial truss structures. These structures have been developed rapidly and have found many applications in China in the recent decade. This paper provides a review of applications and developments of pretensioned long-span steel structures in China. The following topics on new technologies and new structures are given emphasis: prestressed grid structures, cable-stayed grid structures, beam string structures and prestressed segmental steel trusses. Prospects for pretensioned steel space structures are presented at the end of the paper.

     Steel arches may be subject to instability caused by in-plane buckling or out-of-plane flexural-torsional buckling. The in-plane buckling of flat steel arches is addressed in this paper, where the method of virtual work is used to determine the buckling loads of circular arches with either pinned or fixed ends and subjected to a uniform loading distributed radially around the arch, and to a point load at the crown. The formulation includes the nonlinear prebuckling configuration of the arch, in deference to the classical stability formulations that treat the prebuckling response as being linear. Design formulae for the elastic buckling loads of arches are derived, as are the limits of the arch modified slenderness that delineates between antisymmetric and symmetric (snap-through) buckling modes.

     Due to the expansion of micro defects, the mechanical properties of structural steel, such as yielding strength, Young's modulus and hardening coefficient will deteriorate under cyclic loadings, and low cycles fatigue failure may take place. Based on continuum damage theory and experimental results, a cumulative damage mechanics model using effective plastic strain is suggested. A general procedure of FEM analysis considering damage cumulation effects is presented and damage crack criterion is proposed as well. Cantilever members subjected to cyclic loading are numerically simulated with FEM program which took the damage cumulation into consideration. The analytical results agree very well with the experiments, and hence, the proposed cumulative damage mechanics model is demonstrated to be accurate enough to simulate the behavior of steel structures under seismic loading. Since the model proposed in the paper can also calculate the cumulation of the damage, it means that the method can also be adopted to access the seismic behavior of steel structures under earthquakes.

     The behaviour of joints in steel rectangular hollow sections filled with concrete is frequently governed by the deformability of the column face loaded in bending. A good estimate of the joint moment-rotation response relies on the knowledge of the behaviour of this component, yet to be fully characterized. With the objective of providing design procedures for this type of joints within the framework of the component method, already adopted by Eurocode 3 to assess the moment-rotation behaviour of joints, an experimental study on test specimens loaded under monotonic loading is presented. Test setup, tested geometries, instrumentation and a description of the behaviour are described in detail, focusing on the column face stress distribution and deformation pattern. The moment-rotation curves and the resulting models to establish the force-displacement curves are presented. Finally, the paper closes with a discussion of the influence of the main geometrical parameters on the joint behaviour.

     After the Northridge earthquake in 1994, some researches in USA have identified three critical issues that significantly affect the strength and ductility of beam-column connections: (i) fracture toughness of weld metal, (ii) geometry and size of weld access hole, and (iii) control of panel zone deformation. This paper reports the experimental results from the second phase of a major research program on ductility of welded beam column connections under cyclic loadings which is supported by the Natural Science Foundation of China. The experiments focus on the geometry and size of weld access hole. Three new types of connection details are proposed and eight full size specimens are tested under cyclic loading. The ductility, the stress concentration behaviour, and the hysteretic behavior of these connections are investigated. Moreover, the influence of connection details on both the ultimate strength and the premature fracture behaviour of these connections are also analyzed, formulating advices on improvement of connection details. The experimental results provide valuable information for updating the seismic design code of high-rise steel buildings in China.

     A unified structural analysis method is developed in order to take into account the histories of corrosion loss of material and repair on their long-term mechanical performance of steel structures in addition to the histories of the damages caused by excessive external loads, e.g. big seismic loads. This analysis method is characterized by the point that the volume change in material due to corrosion or repair is adopted as a new controlling parameter in addition to the conventional parameters such as load and displacement. By introducing this new parameter, the histories of corrosion and repair process under dead loads is precisely simulated. That is, the change in residual stress and deformation caused by corrosion under dead loads can be accurately evaluated at an arbitrary point of their lifetime. As a result, the effect of this change in residual stress and deformation can be reflected in assessing the ultimate behavior of steel structures, thus improving the accuracy of predicting the long-term mechanical performance of steel structures.

     In modern commercial or residential buildings with high specifications in building services, a common method of incorporating services within the floor-ceiling zone of buildings is to create large openings in the webs of beam members. The openings are most likely to be rectangular or circular, and may be in the form of discrete openings, or a series of openings, along the member length of the beam. Over the past few decades, the structural behaviour of beams with web openings was a popular research topic, and numerous research projects were executed and reported including experimental investigations, finite element studies, and also development of design rules. This paper presents a review on recent developments on design of perforated steel beams with web openings of various shapes and sizes.

     A problem of reflection and transmission of an SH-wave through a self-reinforced elastic slab (layer) sandwiched between two transversely isotropic and inhomogeneous elastic solid half-spaces has been investigated. Formulae for reflection and refraction coefficients are obtained in a closed form and it is found that these coefficients are strongly influenced by the anisotropy and inhomogeneity of the half-spaces and on the reinforcement parameters of the sandwiched layer. These coefficients are computed for different values of heterogeneity parameters of the half-spaces and reinforcement parameters of the sandwiched layer. An effect of thickness of sandwiched layer on these coefficients is also noticed.

     The fundamental equations of plane strain problems in generalised thermoelasticity with one relaxation time parameter including the heat source have been written in the form of a vector matrix differential equation. Integral transform techniques are adopted, namely: the Laplace transform for the time variable and the exponential Fourier transform for one of the space variables. Exact expressions for the temperature distribution, thermal stresses and displacement components are obtained in the Laplace-Fourier transform domain. A numerical approach is implemented for the inversion of both transforms in order to obtain the solution in physical domain. Finally, numerical computations of the stresses and temperature have been made and represented graphically (for different values of time t and relaxation time parameter t as shown in the figures).

     The stress-strain relationship of the deep drawing quality (DDQ) and intersitial free (IF) steel sheets was determined by uniaxial and equibiaxial (hydraulic bulging) tensile tests. The sheet thickness gradation in different points of the hemisphere formed in the bulge test was analysed, both experimentally and theoretically. The Hollomon equation was used to describe uniaxial and biaxial strain hardening curves, and the differential (strain dependent) strain hardening exponent nt was determined on the basis of the results of uniaxial and biaxial testing.

     The parametric instability behavior of a stiffened plate subjected to uniform in-plane edge loading is studied using the finite element analysis. The method of Hill's infinite determinants is applied to analyze the dynamic instability regions. Numerical results are presented to demonstrate the effects of various parameters, such as the aspect ratio, boundary condition, stiffening scheme, on the dynamic stability of stiffened plates. The results show that the location, size and number of stiffeners have a significant effect on the location of the boundaries of the principal instability regions when compared with those of a flat unstiffened plate.

     Thermo-poro-elastic equations describing the pressure and temperature diffusion from a deep layer of high temperature and pressure to a fluid saturated porous permeable layer are considered. The coupled partial differential system is transformed into an ordinary differential system via similarity transformations. Approximate analytical solutions to the ordinary differential system are found using perturbation methods and the criteria for validity of the solutions are established. Series solutions of the ordinary differential system are also given. Perturbation solutions and series solutions are contrasted with numerical solutions. When the criteria are met, perturbation solutions and numerical solutions are in good agreement. In contrast, the series solutions have a limited range of applicability.