Papers by Author: Xiang Lin Gu

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Authors: Xiao Bin Song, Hong Yong Tang, Wei Ping Zhang, Xiang Lin Gu
Abstract: This paper presents the results of an experimental study on the compressive stress-strain relationship of wood confined with fiber composite sheets. Wood cylinders confined with carbon fiber composite sheets along full length were tested by compression load. The tests considered up to three layers of fiber sheets. The results will be used to verify a numerical analysis model, which will be further used to conduct a parametric study of the influential factors. The generated knowledge can be used as reference for strengthening designs of historical timber structures using fiber reinforcing products.
Authors: Mattia Santandrea, Giovanni Quartarone, Christian Carloni, Xiang Lin Gu
Abstract: The rehabilitation of existing masonry elements by means of jacketing of columns using composite materials is becoming a remarkable technique in several applications that aim to increase the strength of existing masonry buildings. Fiber reinforced cementitious matrix (FRCM) composites are a newly developed strengthening system that consist of high-strength fibers embedded in a cementitious grout and externally bonded to the substrate. High resistance to fire and high temperatures, ease of handling during application, and vapor permeability with the substrate are some of the characteristics that make FRCMs a promising alternative to traditional organic composites such as fiber reinforced polymer (FRP) composites. This work presents the results of an experimental study carried out to understand the behavior of masonry columns with a square cross-section confined by steel and basalt fiber sheets embedded in a mortar matrix subjected to monotonic concentric compressive load. The effectiveness of the confinement is studied in terms of load-bearing capacity with respect to unconfined columns. The effect of corner radius for columns confined with basalt fibers is investigated.
Authors: Li Xue Jiang, Shi Ju Zheng, Wei Ping Zhang, Xiang Lin Gu
Abstract: Eight weak reinforced concrete beam-column connections and two strong ones subjected to cyclic loads were tested. Effects of the one-way slab, top reinforcement ratio of the beam as well as the transverse reinforcement ratio inside the joint on the seismic behavior of reinforced concrete beam-column connections were primarily investigated. Tests results show that, when subjected to the negative moment, the beam flexural resistance increases notably due to the presence of the slab. However, failure mode of the weak connection transforms from the beam flexural failure to the joint shear failure, resulting from the increased joint shear brought by the slab participation. Besides, the presence of the slab reduces the ultimate relative rotation, ductility and energy-dissipation capacity of the connection. Generally, weak connections can receive more benefit from the one-way slab than strong connections. Connections with less amount of top reinforcement in the beam exhibit better ductility and energy-dissipation capacity, which indicates that it is not always good to strengthen the beam negative moment zones in existing structures. The transverse reinforcement inside the joint has little effect on the seismic behavior of the weak connection with a one-way slab.
Authors: Xian Yu Jin, Nan Guo Jin, Xiang Lin Gu
Abstract: : In order to analyze the cause of water leakage in highway tunnels, the damage property of waterproof board in composite tunnel lining with concrete matrix defects under hydraulic pressure was studied using Galerkin method for plates with large deflection. The deflection, stress and strain of waterproof boards were calculated in the conditions of rectangular and elliptic boundary due to concrete matrix defects. First strength theory was used to determine the critical load of the board and the critical depth of the defect. Investigation results showed that the maximum principal stress generates in the middle of longer side in the rectangular boundary condition and in the center in the elliptic boundary condition, the failure of the waterproof board under certain hydraulic pressure is related with the dimensions of concrete matrix defects and the dimension of the concrete matrix defect needs to be controlled in the design and construction of waterproof layer for tunnels.
Authors: Xiang Lin Gu, Dong Jie Sun, Kai Sun, Guang Hong Hu
Abstract: Most of the existing historic buildings are masonry buildings in China. Among them, some of buildings have served for a long time, their mechanical performance deteriorated significantly. They need to be inspected thoroughly and assessed accurately for the purpose of protection. However, there is still no available engineering software designed for the reliability assessment of existing historic masonry structures. Therefore, a Masonry Assessment software Package with three modules of pre-processing, core analyzing, and post-processing was developed based on the characteristics of historic masonry building structures. In this paper, the development technology for the software is introduced, and the suitability of the software is verified through the application of the software in a real historic masonry building.
Authors: Ling Li Gong, Nan Guo Jin, Xiang Lin Gu, Xian Yu Jin
Abstract: In this paper, the development of cubic compressive strength of concrete with the age was studied first. Four kinds of concrete, which were made from the mixes by using 0%, 20%, 30% and 40% Composite Mineral Admixture (CMA) as the replacement of the cement for each kind of concrete, were used in the study. Test results showed that the concrete with 30% CMA had the best properties compared with others both under standard-curing condition and steam-curing condition. Furthermore, the normal concrete (without CMA ) and the high performance concrete (with 30% CMA) were chosen as the main materials in comparative tests to study the effect of curing conditions on the property of high performance concrete, such as the basic mechanical properties, the property against chloride penetration, and the property against carbonization. The results indicated that the curing temperature would increase the concrete strength in early age but not in long term. The curing condition would affect the property of concrete against carbonization but not the property of concrete against chloride penetration obviously.
Authors: Nan Guo Jin, Xian Yu Jin, Xiang Lin Gu
Abstract: Taking free shrinkage as the key parameter in evaluating cracking of concrete, the cracking properties of self-compacting concrete with strength grade of C35 and C50 were investigated based on ring and slab restraint tests. Meanwhile, the ultimate tensile strain of self-compacting concrete was studied by using flexural test. Experimental results show that the shrinkage of self-compacting concrete is lower than that of normal concrete. Self-compacting concrete cracks later than normal concrete with the same strength grade. Although the ultimate flexural tensile strains of self-compacting concrete in 7 d and 28 d are a little bit lower than that of the normal concrete, it can still be concluded from the research that the cracking property of self-compacting concrete can be greatly improved by using proper mix proportion.
Authors: Xiang Li, Xiang Lin Gu, Xiao Bin Song, Jian Nan Wang
Abstract: Surveying and mapping the appearance of architecture plane is a supporting technology of historic buildings. To meet the need of plan survey in-house, a new close-range photogrammetry method was developed by laser reticule system. With the help of the system, two parallel level lines and eight vertical laser lines can be marked on the surface of inner walls. When the relationship between the distance from a vertical line and the length of the same line on an image picture is studied, the spatial location of room corners and some characteristic points on the images can be determined. Based on the photogrammetry and plane table operation method, architectural plane mapping can be done easily following a set of laser reticule images which were shot in situ closed by a non-metric digital camera. More details of historic buildings can be recorded on drawing sheets and images monogamy at the same time by using the proposed method, which are the basic information for the structural analysis of historic buildings.
Authors: Wei Cui, Wei Ping Zhang, Xiang Lin Gu
Abstract: In this paper, limit state criteria for safety evaluation of historical buildings according to different target period of usage were introduced briefly. The effect of beam-column connection and the contribution of bricks surrounded columns and infill masonry walls on the seismic behavior of the historical buildings were identified based on calculation results. Main features of performance-based seismic evaluation method, including classification of importance of historical buildings, determination of target period of usage and performance index, were discussed. An engineering project was discussed to illustrate the evaluation procedures, and verify the effectiveness of the evaluation method.
Authors: Feng Lin, Ying Wang, Xiang Lin Gu, Xin Yuan Zhao
Abstract: Important historic buildings may be subjected to accidental loads during their service life. It is therefore necessary not only to evaluate their safety under traditional loads and seismic action (only in earthquake area), but also to evaluate the structural performance of resisting progressive collapse. For historic buildings, two aspects make them different from the modern buildings: the material properties are usually deteriorated to some extent, and the structural system/constructions may not meet the requirements of current design and construction codes. Considering such aspects, a method consisting of four steps to evaluate the performance of the historic buildings to resist progressive collapse is presented in this paper. Firstly, the building layout should be evaluated whether it can protect the occupants from the possible explosion. Secondly, geometrical information, structural constructions and the material properties are to be investigated in details. Thirdly, by means of tie force method and the alternate path method the performance of the structure is analyzed to resist progressive collapse. The load combinations used in the analysis are derived based on the expected service life of the structure. The failure criteria for the structural elements as well as the damage limits for the structure follow the provisions addressed in American Unified Facilities Criteria “Design of Structure to Resist Progressive Collapse” (UFC 4-023-03). Finally, based on the above information an overall evaluation is made for the probably structural retrofitting and strengthening. This method is illustrated with a case study of a steel frame historic building, namely the Bund 18 building, in Shanghai, China. Some suggestions for retrofitting and strengthening this building are also presented.
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