Abstract: Reciprocal frame (RF) structures were developed in this work using pultruded glass fibre reinforced polymer (GFRP) members and the formulation of mathematical model for geometric forming and capacity design of such structures were presented. Firstly, governing geometric relationships are identified for the height, span and slope of the RF structure and its overall geometry can be formed accordingly. Once the geometry is determined, the structure can be analysed to calculate the internal forces of each component and connections under given loads. GFRP pultruded members were used to assemble the RF structure due to their high strength and lightweight. Considering the closed shape of the tubular section and the anisotropy of the materials, an innovative connection configuration was developed to facilitate the assembly and minimise the requirement of tools in the construction. Both the conceptual design and modelling analysis are supported with experimental results at connection and structural levels. The load-drift relationships of the connections were experimentally examined. Subsequently, A GFRP reciprocal frame structure was then assembled with a span of 4.5 m and subjected to multi-point bending to verify the proposed evaluation method and to study its mechanical performance. Verified by experimental results, a two-dimensional numerical model of the RF structure was developed and analysed using the finite element (FE) approach where different structural boundary conditions and connection stiffnesses were discussed. Finally, the geometrical nonlinear analysis was also studied for the structure through FE modelling.
Link to this article: https://doi.org/10.1016/j.engstruct.2021.113420
How to cite this article: CHEA Cheav Por, BAI Yu, FANG Yihai, ZHANG Yimin. (2022). Geometric forming and mechanical performance of reciprocal frame structures assembled using fibre reinforced composites. Engineering Structures, 250, p.113420
Abstract: The riser system is subject to vibration due to marine environmental loads, which can affect the efficiency of the system or even destroy it. This paper proposes a solution for the vibration control problem of a 2-D variablelength flexible riser based on PDE model. Firstly, a disturbance observer is developed to estimate and offset the unknown disturbance in the feedback loop. Based on the above method, an effective boundary controller is designed to realize the elastic suppression goal of the 2-D variable-length flexible riser. Secondly, when considering the asymmetric output constraints, a time adjustment function is introduced to develop a new controller based on the barrier Lyapunov function, which realizes the control objective of suppressing the boundary vibration of the flexible riser within specified constraints in a finite time. Finally, the effectiveness of the controller is verified by simulation examples.
Link to this article: https://doi.org/10.1016/j.oceaneng.2024.119042
How to cite this article: WANG Meng, ZHANG Jianhua, CHEA Cheav Por, SUN Ke, LIU Feng. (2024). Vibration control of 2-D variable-length flexible riser systems with unknown boundary disturbance. Ocean Engineering, 312, p. 119042
Abstract: Optimization design and manufacturing play an important role in obtaining successful composite structures with high efficiency and safe use of materials. In this paper, we first present the optimization design procedure for a composite box girder by ANSYS para metric design language (APDL) in the ANSYS software. The input parameters used in the simulation work were determined via fundamental experimental tests of composite specimens. Then we manufactured the designed composite box girder by moldpressing prepreg technology according to the optimization results. The finial composite girder structure composed of arch top, web and bottom composite plate was obtained. The optimization procedure indicated that the use of stiffening plates in a girder could decrease the weight and increase the failure load. The location and ply mode of the stiffening plates in girder were suggested. The three-point-bending test was performed on the girder, and the test indicated that load-carrying capacity in unit mass of the optimized girder was as high as 107.8 N/g. Simulation and experimental results match well, and the maximum and minimum stresses in each layer were within the strength limitation of carbon material after optimized in the procedure.
Link to this article: https://doi.org/10.1515/secm-2016-0123
How to cite this article: YANG Bin, TONG Lili, CHEA Cheav Por. (2016). Optimization design, manufacturing and mechanical performance of box girder made by carbon fiber-reinforced epoxy composites. Science & Engineering of Composite Materials, 25(2): 297-307.
Abstract: In the design code system of China, frame-core tube structure should be designed as a dual lateral-force resisting system, and there are strict requirements for the secondary lateral-force resisting system of such structure. In other words, the outer frame of the frame-core tube structure should have sufficient lateral stiffness and strength. However, in the design codes of other countries (e.g., ASCE-7 of the United States), the outer frame of the frame-core tube structure is permitted to only carry the vertical load. Therefore, to compare the seismic performances of the single and dual lateral-force resisting systems of the frame-core tube structure, a dual lateral-force resisting system model was firstly designed following the design codes of China. Subsequently, under the same gravity load (and the same concrete consumption), the single lateral-force resisting system model of the frame-core tube structure was design according to the following procedures: 1) the secondary lateral-force resisting system was removed from the dual system, and the shear force adjustment of the frame was ignored; 2) the seismic detailing requirement of the frame was lowered to reduce the sectional size. As a result, the tube beared most of the seismic load, and the frame only resisted the vertical load. The structural responses and component damage of these two systems under SLE (Service Level Earthquake) and MCE (Maximal considered earthquake) were analyzed. Furthermore, the collapse mechanisms of two structures and their collapse-resistances were investigated. Finally, the variation of the shear force and shear distribution of the frame under different levels of earthquake and the corresponding damage of key components were discussed. The research shows that the response of the dual system structure was slightly greater than that of the single system, and their collapse resistant capacities were similar. However, the steel consumption of the single system was less than that of the dual system.
Link to this article: https://doi.org/10.6052/j.issn.1000-4750.2018.11.0635
How to cite this article: CHEA Cheav Por, XIE Linlin, LIN Yuanqing, LU Xinzheng. (2019) Study on seismic performance and collapse-resistant capacity of typical frame-core tube structures with single and dual lateral-force resisting system. Engineering Mechanics, 36(10): 40-49. (in Chinese)