Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such a...Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such as lateral shear deformation, warp generated by nonuni- form torsion and second-order shear stress, coupling of flexure and torsion, and large displacement with small strain. With an additional internal node in the element, the element stiffness matrix is deduced by incremental virtual work in updated Lagrangian (UL) formulation. Numerical examples demonstrate that the presented model well describes the geometrically nonlinear property of spatial thin-walled beams.展开更多
In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single clos...In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This method is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free beading as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method. is introduced to form a,. numerical algorithm. Both static and natural vibration problems of sample box beams axe analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.展开更多
Based on Timoshenko's beam theory and Vlasov's thin-walled member theory, a new model of spatial thin-walled beam element is developed for analyzing geometrical and physical nonlinearity, which incorporates an inter...Based on Timoshenko's beam theory and Vlasov's thin-walled member theory, a new model of spatial thin-walled beam element is developed for analyzing geometrical and physical nonlinearity, which incorporates an interior node and independent interpolations of bending angles and warp and takes diversified factors into consideration, such as traverse shear deformation, torsional shear deformation and their coupling, coupling of flexure and torsion, and the second shear stress. The geometrical nonlinear strain is formulated in updated Lagarange (UL) and the corresponding stiffness matrix is derived. The perfectly plastic model is used to account for physical nonlinearity, and the yield rule of von Mises and incremental relationship of Prandtle-Reuss are adopted. Elastoplastic stiffness matrix is obtained by numerical integration based on the finite segment method, and a finite element program is compiled. Numerical examples manifest that the proposed model is accurate and feasible in the analysis of thin-walled structures.展开更多
The Industrialized Building System (IBS) was recently introduced to minimize the time and cost of project construction. Accordingly, ensuring the integration of the connection of precast components in IBS structures...The Industrialized Building System (IBS) was recently introduced to minimize the time and cost of project construction. Accordingly, ensuring the integration of the connection of precast components in IBS structures is an important factor that ensures stability of buildings subjected to dynamic loads from earthquakes, vehicles, and machineries. However, structural engineers still lack knowledge on the proper connection and detailed joints o fiBS structure construction. Therefore, this study proposes a special precast concrete wall-to-wall connection system for dynamic loads that resists multidirectional imposed loads and reduces vibration effects (PI2014701723). This system is designed to connect two adjacent precast wall panels by using two steel U-shaped channels (i.e., male and female joints). During casting, each joint is adapted for incorporation into a respective wall panel after considering the following conditions: one side of the steel channel opens into the thickness face of the panel; a U-shaped rubber is implemented between the two channels to dissipate the vibration effect; and bolts and nuts are used to create an extension between the two U-shaped male and female steel channels. The developed finite element model of the precast wall is subjected to cyclic loads to evaluate the performance of the proposed connection during an imposed dynamic load. Connection performance is then compared with conventional connections based on the energy dissipation, stress, deformation, and concrete damage in the plastic range. The proposed precast connection is capable of exceeding the energy absorption of precast walls subjected to dynamic load, thereby improving its resistance behavior in all principal directions.展开更多
The hybrid structure consisting of castellated composite beam and compound spiral hoop reinforced concrete column take full advantages of steel and concrete material.To popularize the structural form in real condition...The hybrid structure consisting of castellated composite beam and compound spiral hoop reinforced concrete column take full advantages of steel and concrete material.To popularize the structural form in real conditions,a beam⁃through⁃type beam⁃column connection is proposed.Two 1/2⁃scaled connection specimens were tested and three⁃dimensional finite element models of the beam⁃column connection were set up.The longitudinal reinforcements,concrete beam,and column were simulated by link and solid elements,respectively.The influences of the parameters such as expansion ratio,location of web opening,and original height of steel beam were studied.The results show that connections possessed high initial rigidity.The expansion ratio of steel beam showed more important influence on the connection’s ultimate bearing capacity.For the connection models with steel beam expansion ratio of 1.4,the maximum increment of the ultimate bearing capacity of the connection could reach 28%.In order to prevent the local buckling failure of steel beam from occurring near web opening,the expansion ratio of steel beam should not be greater than 1.3.展开更多
A finite element analysis of the beam-to-column web connection with H-shaped columns was performed using the ANSYS computer program. Based on the finite element analysis and theoretical analysis, a simplified model wa...A finite element analysis of the beam-to-column web connection with H-shaped columns was performed using the ANSYS computer program. Based on the finite element analysis and theoretical analysis, a simplified model was developed to describe the cyclic loading behavior of beam-to-columns web connection in steel moment resisting frames, considering both bending and shear deformation modes of the beam flange plate. Several issues appearing to merit further researches were identified in the process of developing this model, such as the effect of beam flange plate on beam-to-column web connection stiffness and strength. A reasonable agreement was achieved between model predictions and finite element data, which verified the feasibility of the proposed model.展开更多
A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section.The kinetic and potential energies were derived by the virtual principle.T...A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section.The kinetic and potential energies were derived by the virtual principle.The energy function includes the effect of flexural-torsional coupling,the torsion warping and the shear centre location.For finite element analysis,cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements.Each node possesses seven degrees freedom including the warping degree of freedom.The nonlinear eigenvalue problem was solved by the direct iteration technique.The results are compared with those for straight beams as available in the literature.The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.展开更多
Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent ...Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all considered.Thereafter,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are formulated.Ideal plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of Prandtle-Reuss.Elastoplastic stiffness matrix is derived by numerical integration on the basis of the finite segment method.Examples show that the developed model is feasible in analysis of thin-walled structures with high accuracy.展开更多
结合钢筋混凝土结构和钢结构的优势,设计一种型钢-螺栓-后浇混凝土装配式剪力墙型钢混合连接。基于ABAQUS有限元软件建立混合连接的剪力墙模型,探究低周往复荷载作用下该混合连接预制剪力墙的受力性能,主要分析模型的破坏形态、受力机...结合钢筋混凝土结构和钢结构的优势,设计一种型钢-螺栓-后浇混凝土装配式剪力墙型钢混合连接。基于ABAQUS有限元软件建立混合连接的剪力墙模型,探究低周往复荷载作用下该混合连接预制剪力墙的受力性能,主要分析模型的破坏形态、受力机制、变形曲线、特征承载力等,并扩展分析了材料强度、轴压比、连接件数量、型钢截面高度等参数对模型受力性能影响。结果表明:装配式剪力墙破坏形态为压弯破坏,破坏时钢连接件仍保持完整,符合“强连接,弱墙肢”的基本设计理念;装配式剪力墙具有较好的承载力、延性和刚度;轴压比对结构承载力影响显著,型钢混合连接间距的增大能有效提升剪力墙延性。建立了型钢混合连接抗剪需求承载力计算模型和公式,并与国内外规范计算值对比分析,公式计算值和BS EN 1992欧洲规范计算值分别与模拟值的误差在15%和20%以内,均可用于型钢混合连接剪力墙竖缝受剪承载力设计参考。展开更多
基金supported by the National Science Fund for Distinguished Young Scholars (No. 50725826).
文摘Based on the theory of Timoshenko and thin-walled beams, a new finite element model of spatial thin-walled beams with general open cross sections is presented in the paper, in which several factors are included such as lateral shear deformation, warp generated by nonuni- form torsion and second-order shear stress, coupling of flexure and torsion, and large displacement with small strain. With an additional internal node in the element, the element stiffness matrix is deduced by incremental virtual work in updated Lagrangian (UL) formulation. Numerical examples demonstrate that the presented model well describes the geometrically nonlinear property of spatial thin-walled beams.
基金The project supported by the National Natural Science Foundation of China (19932030)
文摘In the present paper, a series of hierarchical warping functions is developed to analyze the static and dynamic problems of thin walled composite laminated helicopter rotors composed of several layers with single closed cell. This method is the development and extension of the traditional constrained warping theory of thin walled metallic beams, which had been proved very successful since 1940s. The warping distribution along the perimeter of each layer is expanded into a series of successively corrective warping functions with the traditional warping function caused by free torsion or free beading as the first term, and is assumed to be piecewise linear along the thickness direction of layers. The governing equations are derived based upon the variational principle of minimum potential energy for static analysis and Rayleigh Quotient for free vibration analysis. Then the hierarchical finite element method. is introduced to form a,. numerical algorithm. Both static and natural vibration problems of sample box beams axe analyzed with the present method to show the main mechanical behavior of the thin walled composite laminated helicopter rotor.
基金supported by the National Natural Science Foundation of China (50725826)Specific Research on Cable-reinforced Membranes with Super Span and Complex Single-shell Structures of Expo Axis (08dz0580303)Shanghai Postdoctoral Fund (10R21416200)
文摘Based on Timoshenko's beam theory and Vlasov's thin-walled member theory, a new model of spatial thin-walled beam element is developed for analyzing geometrical and physical nonlinearity, which incorporates an interior node and independent interpolations of bending angles and warp and takes diversified factors into consideration, such as traverse shear deformation, torsional shear deformation and their coupling, coupling of flexure and torsion, and the second shear stress. The geometrical nonlinear strain is formulated in updated Lagarange (UL) and the corresponding stiffness matrix is derived. The perfectly plastic model is used to account for physical nonlinearity, and the yield rule of von Mises and incremental relationship of Prandtle-Reuss are adopted. Elastoplastic stiffness matrix is obtained by numerical integration based on the finite segment method, and a finite element program is compiled. Numerical examples manifest that the proposed model is accurate and feasible in the analysis of thin-walled structures.
基金financial support from the Housing Research Center of UPMNAEIM Company
文摘The Industrialized Building System (IBS) was recently introduced to minimize the time and cost of project construction. Accordingly, ensuring the integration of the connection of precast components in IBS structures is an important factor that ensures stability of buildings subjected to dynamic loads from earthquakes, vehicles, and machineries. However, structural engineers still lack knowledge on the proper connection and detailed joints o fiBS structure construction. Therefore, this study proposes a special precast concrete wall-to-wall connection system for dynamic loads that resists multidirectional imposed loads and reduces vibration effects (PI2014701723). This system is designed to connect two adjacent precast wall panels by using two steel U-shaped channels (i.e., male and female joints). During casting, each joint is adapted for incorporation into a respective wall panel after considering the following conditions: one side of the steel channel opens into the thickness face of the panel; a U-shaped rubber is implemented between the two channels to dissipate the vibration effect; and bolts and nuts are used to create an extension between the two U-shaped male and female steel channels. The developed finite element model of the precast wall is subjected to cyclic loads to evaluate the performance of the proposed connection during an imposed dynamic load. Connection performance is then compared with conventional connections based on the energy dissipation, stress, deformation, and concrete damage in the plastic range. The proposed precast connection is capable of exceeding the energy absorption of precast walls subjected to dynamic load, thereby improving its resistance behavior in all principal directions.
基金Sponsored by the Open Subject of the State Key Laboratory of Subtropical Building Science(Grant No.2018ZB29).
文摘The hybrid structure consisting of castellated composite beam and compound spiral hoop reinforced concrete column take full advantages of steel and concrete material.To popularize the structural form in real conditions,a beam⁃through⁃type beam⁃column connection is proposed.Two 1/2⁃scaled connection specimens were tested and three⁃dimensional finite element models of the beam⁃column connection were set up.The longitudinal reinforcements,concrete beam,and column were simulated by link and solid elements,respectively.The influences of the parameters such as expansion ratio,location of web opening,and original height of steel beam were studied.The results show that connections possessed high initial rigidity.The expansion ratio of steel beam showed more important influence on the connection’s ultimate bearing capacity.For the connection models with steel beam expansion ratio of 1.4,the maximum increment of the ultimate bearing capacity of the connection could reach 28%.In order to prevent the local buckling failure of steel beam from occurring near web opening,the expansion ratio of steel beam should not be greater than 1.3.
基金Sponsored by the National Natural Science Foundation of China(Grant No.50538050)Foundation of Heilongjiang Educational Committee(Grant No.11521210)
文摘A finite element analysis of the beam-to-column web connection with H-shaped columns was performed using the ANSYS computer program. Based on the finite element analysis and theoretical analysis, a simplified model was developed to describe the cyclic loading behavior of beam-to-columns web connection in steel moment resisting frames, considering both bending and shear deformation modes of the beam flange plate. Several issues appearing to merit further researches were identified in the process of developing this model, such as the effect of beam flange plate on beam-to-column web connection stiffness and strength. A reasonable agreement was achieved between model predictions and finite element data, which verified the feasibility of the proposed model.
文摘A finite element formulation was presented for the nonlinear free vibration of thin-walled curved beams with non-symmetric open across section.The kinetic and potential energies were derived by the virtual principle.The energy function includes the effect of flexural-torsional coupling,the torsion warping and the shear centre location.For finite element analysis,cubic polynomials were utilized as the shape functions of the two nodal thin-walled curved elements.Each node possesses seven degrees freedom including the warping degree of freedom.The nonlinear eigenvalue problem was solved by the direct iteration technique.The results are compared with those for straight beams as available in the literature.The results for nonlinear free vibration analysis of curved beams for various radii and subtended angle are presented.
基金supported by the National Natural Science Foundation of China(Grant No.50725826)
文摘Based on the theories of Bernoulli-Euler beams and Vlasov's thin-walled members,a new geometrical and physical nonlinear beam element model is developed by applying an interior node in the element and independent interpolations on bending angles and warp,in which factors such as traverse shear deformation,torsional shear deformation and their coupling,coupling of flexure and torsion,and second shear stress are all considered.Thereafter,geometrical nonlinear strain in total Lagarange(TL) and the corresponding stiffness matrix are formulated.Ideal plastic model is applied to physical nonlinearity to comply with the yield rule of Von Mises and incremental relationship of Prandtle-Reuss.Elastoplastic stiffness matrix is derived by numerical integration on the basis of the finite segment method.Examples show that the developed model is feasible in analysis of thin-walled structures with high accuracy.
文摘结合钢筋混凝土结构和钢结构的优势,设计一种型钢-螺栓-后浇混凝土装配式剪力墙型钢混合连接。基于ABAQUS有限元软件建立混合连接的剪力墙模型,探究低周往复荷载作用下该混合连接预制剪力墙的受力性能,主要分析模型的破坏形态、受力机制、变形曲线、特征承载力等,并扩展分析了材料强度、轴压比、连接件数量、型钢截面高度等参数对模型受力性能影响。结果表明:装配式剪力墙破坏形态为压弯破坏,破坏时钢连接件仍保持完整,符合“强连接,弱墙肢”的基本设计理念;装配式剪力墙具有较好的承载力、延性和刚度;轴压比对结构承载力影响显著,型钢混合连接间距的增大能有效提升剪力墙延性。建立了型钢混合连接抗剪需求承载力计算模型和公式,并与国内外规范计算值对比分析,公式计算值和BS EN 1992欧洲规范计算值分别与模拟值的误差在15%和20%以内,均可用于型钢混合连接剪力墙竖缝受剪承载力设计参考。