Papers by Author: Zhan Wang

Abstract: The bending capacity of the beam end-plate or the column flange and the tensile property of the bolt could be expressed by an equivalent t-stub model. In this paper, ten groups of different sizes of T-stub are designed for monotonic loading test. The accurate element models are established for comparable study with the experimental result. The stress distribution and deformation characteristics of the T-stub and bolts are determined. A theoretic formula of tensile stiffness for T-stub is derived, it is presented that the calculation results are consistent with the tests.

Abstract: The frame column and frame structure with column end of steel-concrete composite joint is a new-type architectural structure. To obtain the mechanical property of the new-type frame column and frame structure, comparative tests between 6 new-type columns and 3 ordinary columns and comparative tests between new-type frames and ordinary frames are carried out. This paper elabrately introduces the specimen design, experiment load, test program, test results and others. Thus, the transformation and failure characteristics of new-type long and short columns at different axial compression ratios and the transformation and failure characteristics of new-type grames at different prestresses are obtained. They are respectively compared with the ordinary long and short columns and frames. Results show that the seismic performance of the new-type column and frame structure is obviously superior to that of the ordinary ones. The tests can achieve the expected test objectives and are proved successful.

Abstract: Beam-column connection with cantilever beam bolted-splicing is also known as the joint of column-tree moment-resisting frame. The study is still relatively small for the semi-rigid behavior and rotational stiffness of the joint. This paper deal with four specimens of the joints with cantilever beam splicing and four specimens of the welded joints by using three dimensional finite element model analysis. The strain, stress, yield and ultimate loads, yield and ultimate deformations had been compared between the joint with cantilever beam splicing and the welded joint. The analysis results show that, when the splicing area of the joint with cantilever beam splicing was designed more strongly, the stress distribution, the load-displacement curves in elastic working stage, and the initial rotational stiffness are good agreement between the joint with cantilever beam splicing and the welded joint. The hysteresis curves of the joint with cantilever beam splicing were inverse S-shaped, indicating that there was greater slipping deformation because of bolt splicing. The welded joint had no slipping phenomenon.

Abstract: Considering the elastic-plastic stage of steel constitutive relationship, the assumption that element is elastic perfectly-plastic is no longer valid. The yield function that considers the effect of trilinear model is derived by using section assemblage concept. Element with two subsprings at each end is presented to consider the effect of section stiffness and yielding. Based on the proposed yield function and element, an efficient nonlinear analysis method for steel frame with trilinear model is proposed. The proposed element has the same nodal degrees of freedom as conventional beam-column element by condensing the non-nodal degrees of freedom. Other factors influence the capacity of steel frames, such as shear deformation, residual stress, geometric and material nonlinearity are explicated. The efficiency and accuracy of the proposed approach are demonstrated through the numerical example.

Abstract: The moment behavior of beam-column connections should be considered in advanced steel space frame analysis. A trilinear model and calculation method were presented. Based on the comparison with the FEM results, it has been proved that the M-θ relationship of semi-rigid end-plate connections can be accurately estimated by this simplified calculation method and satisfy the requirement of structural design. This calculation method is simple and ease of use, it benefits application of this kind of joint in actual structure engineering and provides the basis and reference for design of the semi-rigid connection.

Abstract: Comparing with the frame structure without any aseismic members, bracing-frame is a better form for the aseismic frame structure. But the form of bracing –frame is determined by the engineering experience. The best design plan can’t be determined using the traditional design method. In order to find the optimal result for the bracing –frame structure, the bracing system topology and the semi-rigid connection topology was considered in this paper. And the optimal model was built based on on discrete topology math model. And the dominant winning role for genetic algorithm was adopted due to a large number of non-linear problems. Through the optimal design for active semi-rigid frame bracing system based on discrete topology method, we can get the best design plan in whole structure system, which have better engineering significance and reference value usually.

Abstract: In structure design, for expressions with partial safety factors, partial safety factors and nominal value of loads are calculated based on the presupposition that the design reference period is 50 years. When the design reference period is not 50 years, it would cause unclear reliability of building structure by using expressions with partial safety factors following correlative codes yet. It may lead to hidden dangers in that way. In order to derive expressions with partial safety factors suitable for any design reference period, two useful methods are shown in this paper, modification of partial safety factors and modification of importance factor of structures. From results of analysis, we get the conclusions that it can assure the reliability index of the expression using the method of modification of partial safety factors, and the method of modification of importance factor of structures is very simple, but cannot assure the reliability index of the expression.

Abstract: In order to hurdle the limitations of Monte Carlo method and Response Surface method, the advanced Monte Carlo method was shown in this paper. And the system reliability of a one-bay and three-story steel framework structure was analyzed using the improved Monte Carlo method. Results of reliability analysis showed that there were high precision and a short calculating time using the improved Monte Carlo method. Then, the model of optimal design for steel frame based on the system reliability was built in accordance with the improved Monte Carlo method. And the optimal design on the steel frame was shown using the modern optimization method--genetic algorithm. From results, it was proved that optimal design without reliability could make structure have not enough reliability, even would not reach the required level of structural safety of Chinese criterions. It may lead to hidden dangers when only to reach objection on economy but haven’t considering reliability.

Abstract: The type of beam-to-column connection in framework structure is determined beforehand in analyzing the frame structure using traditional design method. But it is not comprehensive and exact following that idea. It is difficultly to find the better and more proper design result such as the type of beam-to-column connection and the section of member in many viable design results. Therefore, a new design idea on steel frame -- the active semi-rigid connection design method is advanced in this paper. And some examples on the active semi-rigid connection design and the active semi-rigid connection optimal design are showed. From results, the type of semi-rigid connection makes an important effect on the mechanical behavior of the frame; it will cause the mechanical behavior of the frame to change obviously. And it will be got a better optimal result which considering more comprehensively in the whole frame view based on semi-rigid connection optimal design.

Abstract: Application of continuum structural topology optimization methods to the layout design of bracing systems for multistory steel frame buildings under earthquake loads is explored in this work. A weighted average strain energy sensitivity of element is formulated to be served as the element removal criterion in the optimization process, and then an ESO-based continuum structural topology optimization method for the layout design of multistory steel frame bracing systems subjected to earthquake-induced ground motions is presented. In each iterative design, an approximate reanalysis technique named CA method is adopted to reduce the computational effort. Finally, a design example is given to demonstrate the effectiveness of the presented optimization method for the optimal layout design of steel frame bracing systems under earthquake loads.