Papers by Keyword: Strengthening

Paper TitlePage

Authors: Xiao Ling Zhao, Masoud Motavalli
Abstract: There is a great potential in using fibre reinforced polymer (FRP) to strengthen aging metallic structures. This paper briefly describes the benefit of using FRP to strengthen metallic structures. It then addresses how fatigue load affects the bond between FRP and steel. FRP fatigue strengthening of cracked steel plates and connections are discussed. Furthermore, effects of using prestressed FRP on flexural and fatigue behaviours of a FRP-steel composite system are addressed. Bonded and un-bonded FRP-to-steel applications, as two different approaches for steel strengthening, are discussed. Finally fatigue strengthening of metallic riveted bridges using un-bonded pre-stressed FRP plates is presented. A comprehensive list of references is provided.
Authors: Sheng Nan Huang, Xin Zheng Lu, Lie Ping Ye
Abstract: A hysteretic model of conventional steel braces consisting of 18 parameters is proposed. This model is able to simulate the hysteretic behavior of conventional steel braces accurately. The collapse-prevention strengthening effect with steel braces for a typical reinforced concrete (RC) frame that was close to the epicenter and collapsed during the Great Wenchuan Earthquake is discussed via push-over analysis and collapse fragility analysis based on incremental dynamic analysis. The result could be referred to for the seismic collapse prevention design of RC frames.
Authors: Yi Ye, Shen Shan Pan, Zhe Zhang
Abstract: The method of strengthening the existing reinforced concrete suspension bridges by changing suspension system into cable – stayed- suspension system is presented in this paper. Based on a typical bridge, the analysis of the static behavior of the bridge before and after the strengthening is preformed. The results show that the bending moment of the girder is reduced obviously and the capacity of carrying load is greatly improved. The original cable system is fully utilized and can meet force requirement. It has certain theory significance and practical engineering value to the similar bridge’s strengthening.
Authors: Daniele Ferretti, Eva Coisson, Marco Rozzi
Abstract: The present paper concentrates on the numerical modelling of masonry vaults, adopting a type of analysis first developed at the University of Parma for applied mechanics, based on the use of non-smooth dynamics software, through a Differential Variational Inequalities (DVI) formulation specifically developed for the 3D discrete elements method. It allows to follow large displacements and the opening and closure of cracks in dynamic field, typical of the masonry vaulted structures. Once the modelling instrument was calibrated, thanks to the comparison with the recurrent damage mechanisms previously analysed, it was also applied to foresee the behavior of the same structure with different actions and with different types of strengthening. The development of damage mechanisms, both in quasi-static cases (for insufficient lateral confinement or for possible soil settlements) and in the occurrence of seismic events, make this type of structures very difficult to be modelled precisely with other methods. Given the three-dimensional CAD model of a vault modeled with a great number of masonry units with specific positions and pattern, the method proved to be able to reproduce the behavior of the structure under both static and seismic loads, showing the mechanism of collapse, the network of contact forces, the displacements and other useful data. The aim is to inspect the possible influences in the structural behavior given by the discrete geometry and the changes in the mechanisms development given by different strengthening interventions. Once the modeling instrument will be calibrated, also through the comparison with real cases and with the results obtained through limit analysis, it will be possible to adopt it as a base also for the prevision of the future behavior of the vaults subjected to strengthening, avoiding uncalibrated and uncritical applications of materials based more on trends rather than on a thorough analysis for the specific case.
Authors: E. Wen Huang, Yan Dong Wang, Bjørn Clausen, Michael L. Benson, Hahn Choo, Peter K. Liaw, Lee M. Pike
Authors: De Ying Zhang, Yun Sheng Li, Chun Lei Cui
Abstract: Some retrofitted methods are introduced, and in these retrofitted methods, a strengthening case of using the sandwich plate system (SPS) to strengthen the orthotropic steel bridge deck of a suspend bridge was studied. A local finite element model is established by ANSYS based on an orthotropic steel bridge deck sample, stress distribution of deck due to the wheel load of the vehicle defined in China current code were analyzed under different loading conditions, and the strengthening effect with SPS was evaluated. The influence of the thickness and elastic modulus of elastic sandwich on the transverse stress of deck was analyzed. The results show that, compared with the orthotropic steel bridge deck before strengthened, the stress peak is decreased obviously without new welding residual stress be generated, and the fatigue resistant of bridge deck is increased apparently after the deck strengthened by SPS. The variation of the thickness and elastic modulus of the elastic sandwich have little influence on the stress behaviours of the orthotropic steel bridge deck.
Authors: Wei Wei, Kun Xia Wei, Igor V. Alexandrov, Fei Wang, Jing Hu
Abstract: The composite filament structure was produced in the Cu-5.7%Cr and Cu-12.4%Cr as-cast alloy ingots by using equal channel angular pressing (ECAP) at room temperature. Optical and TEM microstructure, micro-hardness, tensile strength and electrical conductivity of ECAPed samples were investigated. The rotation and spreading of Cr particles took place during ECAP, and resulted in long thin in-situ filaments. The tensile strength increased with the number of the ECAP passes. A strengthening model was recommended to predict the enhancement of the tensile strength in Cu-Cr in situ fibrous composites.
Authors: Hua Jun Liu, Yong Qi, Bing Zhang
Abstract: Crane and part of the column section of a monolayer industrial plant has a collision caused by uneven settlement of the foundation pillar. Based on the test on column bracket elevation, a overall uplift scheme for the basis of larger settlement has been proposed:truncate the middle column and stuff steel columns the same size as the original column section in the middle of column,then weld the column section and the truncated,upper and lower column groove. Flange plate and web plate are reinforced by steel plate and angle steel.Truncated steel columns can be lifted by down chain with a simple installation gantry, meanwhile control the displacement of uplift,preventing offset.
Authors: Hai Yan Wang, Hui Ping Ren, Zong Chang Liu
Abstract: Microstructure evolution of Fe-1.18%Cu high purity steels during solution and aging was investigated under high-resolution electron microscope (HREM). In addition, the aging strengthening mechanisms were discussed based on the microstructure observation. The results show that there were lots of Cu atom clusters in ferrite matrix during solid solution and aging initial stages, subsequently, Cu-rich metastable Fe-Cu particles precipitate at the aging strength peak. It is found that the intense strengthening is controlled by the coherency relationship of Fe-Cu metastable phase with matrix that forms the obstacle of the dislocation motion, while the decrease of strength after the peak is attributed to the loss of coherency, which should highly likely be the dominant reason of aging strengthening in Cu bearing high purity steels Thus our TEM observation results are in reasonably agreement with some previous assume.
Authors: Hua Ping Liao, Shi Sheng Fang
Abstract: Three reinforced concrete (RC) beams strengthened by high-performance ferrocement and two control specimens without strengthened are investigated when RC beams have low compressive strength. Flexural behaviors of strengthened RC beams with high-performance ferrocement are evaluated based on comparative analysis with RC beams. The strengthening results of steel meshes with U-shape (i.e. ferrocements are put onto the tension face and two profile faces) are analyzed. The flexural capacity, deflection and crack width of RC flexural beams are measured, and then comparative analysis is carried out for deformation performance and law of crack development. The test results show that ferrocement contributes greatly to increase the flexural capacity and raise crack-resisting capacity. The experimental results can provide a theoretical reference for actual engineering designs.
Showing 1 to 10 of 302 Paper Titles