Shanshan Cheng

Sidewall Buckling of Equal-Width RHS Truss X-Joints

AbstractThis paper presents a new design methodology for equal-width rectangular hollow section (RHS) X-joints failing by sidewall buckling. In the new approach, a slenderness parameter is defined based on the elastic local buckling stress of the sidewall, idealized as an infinitely long plate under patch loading. A Rayleigh-Ritz approximation is thereby used to obtain a closed-form solution. The proposed design equation is verified against experimental results over a wide range of wall slenderness values obtained from the literature and complemented by a brief experimental program carried out by the authors. It is demonstrated that the new design equation yields excellent results against the experimental data. Finally, a reliability analysis is performed within the framework of both the Eurocode and the AISI standards to ensure that the proposed design equation possesses the required level of safety. The newly proposed equation strongly outperforms the current Comite International pour le Developpement e...

Thermal Buckling Analysis of Axially Loaded Columns of Thin-Walled Open Section with Nonuniform Sectional Properties

This paper presents an analytical study on the thermal buckling analysis of axially loaded columns of thin-walled open section with nonuniform sectional properties. Obtained herein are critical loads related to flexural, torsional and flexural-torsional buckling of an I-section column subjected to an axial compressive load applied at the geometric centroid, and under linearly varied non-uniform temperature distribution scenarios. The analysis is accomplished using traditional energy methods. The influences of thermal strain, nonuniform distribution of pre-buckling stresses, and variation of pre-buckling stresses along the longitudinal axis of the column on critical buckling loads are examined. The present results highlight the importance of nonuniform sectional properties in the buckling analysis of columns of doubly symmetric section.

Finite Element Analysis of the Subsidence of Cap Rocks during Underground Coal Gasification Process

This paper discusses the possible surface subsidence and deformation of the overlying rock during the underground coal gasification (UCG) process, which is an important part of feasibility studies for UCG operations. First coal seam roof movement and surface subsidence in the shallow UCG process were simulated by a finite element model coupled with heat transfer module in COMSOL. Numerical results from this model were compared with and in good agreement to the existing studies. This was followed by the development of model for deeper coal seam cases. The comparison of the numerical results from two models shows that surface uneven settlement in deep underground coal gasification is only 7% of that in shallow underground coal gasification.

Study of Transverse Section Temperature Distribution in Underground Coal Gasification

In order for current laboratory studies of strata performances under high temperature to be applied in Underground Coal Gasification (UCG) technology, the temperature scope (range) of UCG must be studied. Based on the heat conduction differential equation, this paper simulates the transverse section temperature distribution of UCG in the multi-physics coupling field. It demonstrates that the strata properties at a range of two meters are affected by high temperature, and the influence on sandstone is more obvious than that of coal. The temperature curves show a trend of linear to nonlinear as time goes. This paper presents the precedent of using multi-field coupling calculation to simulate UCG.

Numerical Simulation of Natural and Super-Critical Carbonation on Concrete Porous Brick

Based on the partial differential equations on the carbonation of porous materials, this paper develops the natural and super-critical carbonation model by the multi-physics field coupling software to simulate and predict the relation between carbonation degree and the period of carbonation. It is shown that the carbonation degree after 1 day under super-critical condition is equivalent to that after 1 year under natural condition. The bidirectional carbonation makes the concrete porous brick carbonated faster than the concrete block, thus it is suitable for commercial production.