Time filter

Source Type

Zhang C.,Zhejiang University | Wu H.,Finance and Economics of Zhejiang College | Gao B.-Q.,Zhejiang University
Zhendong yu Chongji/Journal of Vibration and Shock | Year: 2011

Based on large-scale numerical calculations for different forms of grid structures subjected to earthquake, dynamic failure modes and characteristics were analyzed, assuming the failure criterion is that the maximum displacement exceeds 1/50 of the span. Dynamic failure modes of grid structures are determined by four factors: the proportion of 8P bar, the maximum displacement during full-time history, the average plastic strain energy, and the ratio of the average to maximum displacement before expiration. As the failure mode is fuzzy, the four factors were analyzed using fuzzy C-means method, and the failure modes were classified into three categories: instability-based progressive collapse, strength-based overall collapse and strength-based progressive collapse, which are described by natural and numerical language respectively. The results show that fuzzy C-means method can effectively classify the failure modes of grid structures, and transform the description from natural to numerical. The numerical prototypes of failure modes were obtained, which can be used to recognize other unknown types of grids, and lay the foundation for performance-based design.

Wu H.,Finance and Economics of Zhejiang College | Cen D.-Q.,Zhejiang University | Gao B.-Q.,Zhejiang University
Zhejiang Daxue Xuebao (Gongxue Ban)/Journal of Zhejiang University (Engineering Science) | Year: 2011

There are some problems for cable dome structures, like the ridge cables are easy to be out of work, the construction requires high technology and outermost ring beams are always with high compressive force. To solve these problems, a type of rigid cable dome structure was presented, replacing ridge cables by rigid members. Approximate optimization was carried out using uniform design method. As an example, a 60m-span Geiger rigid cable dome subjected to symmetrical uniform load was analyzed using U12(37) uniform table. First the approximate functional relation between outcome indicators and design parameters was established. Then an approximate optimum rigid cable dome structure was obtained and the optimum result was verified by extreme value analysis. On this basis, comparing with the conventional cable dome, conclusions are arrived that the upper chords of rigid cable dome structure are under tension, only diagonal cables are necessary to be tensioned during the structural construction and the force of outermost ring beam decrease gradually with the load increasing.

Wu H.,Finance and Economics of Zhejiang College | Zhang R.,Shanghai Nuclear Engineering Research and Design Institute | Zhang R.,Zhejiang University | Gao B.-Q.,Zhejiang University
Gongcheng Lixue/Engineering Mechanics | Year: 2011

In order to investigate the effect of material damage accumulation, semi-rigid joints and rigid zone of joints on the dynamic behavior of suspend-dome structures under severe earthquakes, finite element analysis was performed on welded ball joints subjected to axial force and bending. The M-θ curves of welded ball joints were obtained, and then the semi-rigid joint model was established. Furthermore, five suspend-dome models considering semi-rigid joints, rigid zone of joints and material damage accumulation respectively were analyzed. The results show that: semi-rigid joints and material damage accumulation cause fully-developed structural plasticity and uniform structural stiffness; the structural failure areas, failure modes and the structural ductility are also changed. So the semi-rigid joints, rigid zone of joints and material damage accumulation have a great impact on the dynamic behavior of suspend-dome structures.

Shan Y.-L.,Zhejiang University | Wu H.,Finance and Economics of Zhejiang College | Gao B.-Q.,Zhejiang University
International Journal of Space Structures | Year: 2014

This article finds out the topology configuration and prestress which have the optimal robustness of cable-supported shells as follows. The structure robustness evaluation index is assessed by the H2 norm of system transfer function. The robustness based structure design is transformed into continuum topology optimization by using SIMP material model. The improved Big bang-Big crunch (BB-BC) method employing pseudo-gradient factor is used to get the optimal solution of the topology configuration and prestress joint optimization. Examples show that the improved BB-BC method can solve the joint optimization problems effectively. Topology configuration of the cable-supported shell with a single strut varies with the initial prestress conditions reasonably. The comparison of the joint optimized topology configurations of cable-supported shells with different struts shows that the distribution of material of the shell with five struts is more uniform than that of the shell with a single strut.

Gao B.,Zhejiang University | Cen D.,Zhejiang University | Wu H.,Finance and Economics of Zhejiang College
Shenzhen Daxue Xuebao (Ligong Ban)/Journal of Shenzhen University Science and Engineering | Year: 2013

To solve the withdrawal problem of ridge cables and the singleness of the form in cable dome structures of cable dome structure, a new square rigid cable dome structure is presented, and the clearance of the new structure is higher than that of the beam string. A 48 m-span and 1/16 rise-span ratio square rigid cable dome is studied. The Monte Carlo method based on orthogonal design response surface is employed to analyze the reliability sensitivity under double randomness. Compared with a beam string of the same span and rise-span ratio, the results show that the maximum displacement of the square rigid cable dome is smaller than that of the beam string. Controlled by displacement, the random variables including sectional area of rigid member and load are more sensitive for square rigid cable dome structural failure while sectional area of rigid member, load and prestress level of outermost diagonal cable are more sensitive for beam string structural failure.

Wu H.,Finance and Economics of Zhejiang College | Gao B.-Q.,Zhejiang University | Chen Q.,Zhejiang University
Journal of Zhejiang University: Science A | Year: 2012

A type of hollow cylinder joints connected with H-shaped beams is proposed for spatial structures. Based on von Mises yield criterion and perfect elasto-plasticity model, a series of finite element models of the joints is established, in which the effect of geometric nonlinearity is taken into account. Then mechanical behavior and load-carrying capacity of the joints were investigated, which were subjected to axial load, in-and out-plane bending moments, and their combinations. The results show that the ultimate loads of the joints are determined by the maximum displacement. Furthermore, the case of one joint connected with multiple beams was discussed. Experiments on a set of typical full-scale joints were conducted to understand the structural behavior and the failure mechanism of joint, and also to validate the finite element models. Finally, the practical calculation method was established through finite elements analysis (FEA) results and numerical fitting. The results show that the joints are more ductile and materially economical than welded hollow spherical joints, and the practical calculation method can provide a reference for direct design and the revision of relevant design codes. © 2012 Zhejiang University and Springer-Verlag Berlin Heidelberg.

Loading Finance and Economics of Zhejiang College collaborators
Loading Finance and Economics of Zhejiang College collaborators