Wei Lian Qu

Multi-Scale Elastoplastic Dynamic Analysis of Steel Frame Welded Connections under Strong Earthquake Excitation

Multi-scale elastoplastic dynamic analysis of the welded connections is conducted under the strong earthquake excitation based on a steel frame engineering case. Two types of multi-scale model are built for the contrastive analysis, and the plastic deformation of the connection section is extracted to investigate the application of the plane-section assumption. The results indicate that elastic-plastic status makes the column and beam sections not meet the flat section assumption. Finally, the determination method of the refined modeling zone is studied based on the application of the plane-section assumption.

Multiaxial Fatigue Life Prediction of Metallic Materials Based on Critical Plane Method under Non-Proportional Loading

The critical plane method is widely discussed because of its effectiveness for predicting the multiaxial fatigue life prediction of metallic materials under the non-proportional loading conditions. The aim of the present paper is to give a comparison of the applicability of the critical plane methods on multiaxial fatigue life prediction. A total of 205 multiaxial fatigue test data of nine kinds of metallic materials under various strain paths are adopted for the experimental verification. Results shows that the von Mises effective strain parameter and KBM critical plane parameter can give well predicted fatigue lives for multiaxial proportional loading conditions, but give poor prediction lives evaluation for multiaxial non-proportional loading conditions. However, FS parameter shows better accuracy than the KBM parameter for multiaxial fatigue prediction for both proportional and non-proportional loading conditions.

Experimental Study on Extremely Low-Cycle Material Fatigue Resistance for Two Types of Welded Structural Details

Extremely low-cycle fatigue and fracture is one of the most critical damage types of the welded beam-to-column connections when the steel frame subjected to the strong earthquake excitation. The investigation on extremely low cycle fatigue behavior of welded structural details is useful for the fatigue design of welded structure. In the present study, extremely low cycle material fatigue tests were carried out to examine the fatigue failure mechanism of two types of welded structural details, which were the plate butt weld (PB) specimen and cruciform load-carrying groove weld (CLG) specimen. Fatigue tests were performed on 12 welded specimens under strain-controlled constant loading in the plastic range. The fitting S-N curves of the two types were presented. The fatigue S-N curves of the similar welded structural details in IIW Fatigue Recommendation was adopted to correlate the fatigue resistance of the two types of welded structural details. The results demonstrated that the failure mode of PB specimens was not the same as that of CLG specimens. The extremely low-cycle material fatigue strength of the investigated welded structural details was lower than expected high cycle fatigue S-N curves provided by IIW, showing shorter fatigue lives, which indicated that the cumulative damage of welded details involved ductile damage besides cyclic fatigue damage in extremely low-cycle fatigue situation.

Comparative Analysis of Davenport Wind Spectrum and Kaman Wind Spectrum in the Towering Structural Design

To the Yangtze River a long-span transmission tower as an example, this paper makes a comparative analysis on the davenport wind spectrum and kaman wind spectrum, using two different wind spectrum calculation of wind-induced response of the structure. Obtained the conclusions that kaman wind spectrum of considering vertical correlation get greater wind-induced response in a large span transmission tower engineering.

A Comparison of Fatigue Design Recommendations for Welded Details

The fatigue strength of weldments is remarkably different form smooth specimens due to the welding. To deal with the fatigue assessment of the various types of the weldments, the weld detailing catalog is widely adopted in the fatigue recommendations. This paper focuses on the comparison of fatigue design recommendations for welded details. Meanwhile the resent development method in the fatigue assessment is also discussed.

Study on Distributed Properties of Welding Residual Stress in Bridge Nodes

The distributed properties of residual stress in bridge nodes have been investigated in the paper. Based on some bridge node, the three dimensional thermodynamics finite element model has been established, meanwhile, the double ellipsoidal distributed heat source model are used to simulate the whole welding procedure of bridge nodes according to the welding parameters. Thus, the distributed regularities of residual stress of bridge node have been obtained. Simulating results show that the residual stresses distribute uniformly in the welding direction, and the max value reaches the yield strength of steel Q345qD. Besides, the residual stress in the lateral direction reaches the max value in the place of welding district, and decreases rapidly when far away from the welds.

Welding Residual Stress Numerical Simulation of Guyed Mast Earplate Welded Joint

Fatigue damage of guyed mast earplate welded joint is one of the main failure forms of guyed mast under wind load, and the welding residual stress is a important influence on fatigue performance of the welded joints, therefore, accurate welding residual stresses assessment of earplate welded joint is of great significance to the research on fatigue performance of guyed mast earplate welded joint under wind load. In this paper, welding temperature field of earplate welded joint was simulated by using thermal finite element method and the gauss heat source was used as thermal input. Then, welding residual stress of earplate welded joint was simulated by using thermal elastic-plastic finite element method and the temperature field results were used as the load. The welding temperature field simulation results better reflect the locality of heating, mobility of heat source and instantaneity of heating and cooling process during the welding process. The welding residual stress simulation results show that the residual stress peak of earplate welded joint reaches the yield strength of material, and appears at the dangerous point of earplate welded joint under structural external load. This point under influence of the welding residual stress and structure load is likely to be fatigue crack initiation location.

The Impact to the Guyed Mast Welding Earplant Joint's Wind-Induced Cumulative Fatigue Damage by Different Eliminate Proportion of Welding Residual Stress

This paper proposes a method to quantitative assess the impact of welding residual stress to structures cumulative fatigue damage. We use ANSYS finite element software to eliminate the welding temperature field and welding stress field, and by changing the load order, preheat consider we can get the welding residual stress of different eliminate proportion. Based on critical damage plane method we finish the welding earplant joint s wind-induced cumulative fatigue damage by different eliminate proportion of welding residual stress .

Dynamic Analysis of Power Transmission Tower Collapse with Wind Load

Transmission tower collapses in adverse weather conditions now and than,which always accompanied thunderstorm.The simulation of transmission collapse under downburst wind load is studied. The tower is modeled as an assembly of beamcolumn elements,fournode isoparametric curved element,and prestressed pole unit simulation insulator,using bilinear restoring force model to formulate the material nonlinear.Simulated downburst wind load time history samples,apply it as external load to the established transmission tower model.Analysis of transmission tower know that transmission towers destroyed in the lower part of the body of the Tower, compressive failure modes in the beam , causing transmission towers final collapse.

Transmission Tower Collapse Analysis with Wind Load Based on LS-DYNA

Large span transmission tower is the lifeline of electricity transmission，Its collapse destroyed will causes adverse to the social and economic effects，The mechanism of the power transmission tower collapsed caused peoples attention.The analysis is based on LS-DYNA program，explicit beam161 beam element is adopted to establish the finite element model for transmission towers，Analyses the collapse process of transmission tower and its failure mode with downburst load.