Papers by Author: Lian Guang Jia

Abstract: In order to research the random initial imperfections on the influence of steel braced frame structures deformation,the full-path advanced analysis by using the finite element software ANSYS for 20-story steel frame structures with the symmetrical arrangement of brace.The random initial imperfections in structural system and its individual members could be taken into account by Monte Carlo method,the lateral displacement of columns and the mid-span deflection of beams are gained according to probability statistics,and analysis method of various standards were compared.Results indicate that the ultimate deformation of steel braced frames are proportional to the size of the initial imperfections;The braced frame deformation considering random initial imperfections are closed to the results of ideal frames without imperfection.The ultimate bearing capacity calculated by advanced analysis of high-rise steel braced frame structures often does not meet the requirements of serviceability limit ,structural design ultimately controlled by the displacement limit.

Abstract: The serviceability limit state of structures is subject to increasing attention. Flooring-systems may encounter vertical vibrations that may be perceived as annoying by stationary persons sitting or standing on the structure. This paper looks into human induced floor vibration of a 33-storey residential building by using theoretical analysis and in-situ inspection. The results show that though the vertical eigenfrequency of the floor satisfies the demand of vibration comfort stated in the Technical Specification for Concrete Structures of Tall Buildings (JGJ3-2010), the maximum value of vertical vibration of the floor system is excessively large, which is caused by the stiffness shortage of the floor due to the decreased floor thickness.

Abstract: In this paper, based on the Midas/gen platform, a three-dimensional finite element model (FEM) for a transfinite stadium with a large-span and large-cantilever roof , located in Shenyang, was used to study its potential responses to seismic activities. In the numerical analysis, an earthquake spectrum stipulated by the Chinese Seismic Code (GB50011-2010) was adopted to calculate the bidirectional horizontal displacements by the Complete Quadratic Combination (CQC) method on the basis of the response spectrum analysis. The computational results indicate that the maximum displacements in both of the two horizontal directions locate at the top of this structure, i.e. the transfinite part of the roof.

Abstract: For floor serviceability, stiffness and resonance are dominant consideration in the design of long-span floor systems or large-cantilever floor systems, which usually have lower stiffness and smaller dampings. In this paper, a dynamic characteristics test of long-span cantilevered floor systems in Shenyang Culture & Art Center was performed by using pulsating methods to determine the natural frequencis and the dampings, which were compared with those from the numerical modal analysis based on the Midas/gen platform. The research provides a basis for a further study of floor vibrations due to human comfort.

Abstract: In this paper, a further research has been carried on mechanical properties of concrete filled steel tube reinforced concrete columns after exposure to fire. A finite element analysis (FEA) model for concrete filled steel tube reinforced concrete columns after exposure to fire under axial compression is developed by ABAQUS. The temperature of cross-section element after exposure to fire has been obtained. The FEA model of temperature field is then used to investigate the mechanism of such composite columns further. Influences of parameters on Load-bearing Capacity such as fire duration time and steel ratio were analyzed. The work in this paper provides a basis for further theoretical study on concrete filled steel tube reinforced concrete columns after exposure to fire.

Abstract: This paper presents finite element analysis on cold-formed steel-section columns with complex edge stiffeners and web holes under axial compression. A total of 18 channel models with different parameters such as length, thickness and flange width are simulated. Failure modes, the ultimate load and the stress distribution around web holes are researched. The analysis results show that, the main failure mode of-section columns with complex edge stiffeners and web holes is distortional buckling. The carrying efficiency is higher as the thickness-width ratio increasing. Because of perforations on the web, the position of the max stress changes from the web near the mid-height of the specimens to the location adjacent to holes.

Abstract: This paper presents an experimental investigation and a numerical analysis on the bending strength and behavior of cold-formed steel C-section and ∑-section beams with complex edge stiffeners and web holes. Local buckling, distortional buckling and interaction between local and distortional buckling were observed in the tests. The experimental results show that the stiffened web has great influence on member's bending strength. Compared with C-section specimens, the stiffness of the web stiffeners of ∑-section specimens reduced the influence of the holes. The finite element analysis results show good agreement with the experimental results in terms of bending strength and buckling mode.

Abstract: Castellated components have many advantages such as high bearing capacity, better bending stiffness, reasonable cross-section form and significant economic benefit. Castellated components are weakened by the reason of web openings, so it is more prone to appear local stability problem. Therefore, the researches of local stability in castellated components play a very important role in the application of the castellated components. In this issue, scholars at home and abroad do a lot of researches, including theoretical research, numerical simulation analysis and experimental research. But the research of castellated bending components are still in groping stage .That has seriously hampered the application and promotion of castellated components in China. So it is necessary to study the local stability of castellated components.

Abstract: Structure may encounter higher seismic fortification intensity than adopted. So how the structure reacts in that case becomes a concerned problem for civil engineers. In order to solve the problem, the response of a steel braced frame structure is analyzed in this paper when facing higher seismic fortification intensity. The result shows that the lateral sway between layers, the vertex displacement, the bending and shear strength of the frame beams and the stability of the components are still meet the design requirements, and steel frame structure has good seismic performance.

Abstract: In order to find out the mechanics behaviors of the inclined CFST stub columns which are used in some real engineering projects, a series of tests are performed and a total of 6 specimens with circular section were experimented. The main parameters were the inclined angle (0 degree and 9 degree) and with or without infilling concrete. Comparisons between measured sectional strengths and predicted sectional strengths using the existing codes were made. The results show that the circular inclined CFST stub columns behaved in a ductile manner and all the codes were conservative and available for predicting the capacities of the specimens.