The Experts below are selected from a list of 15984 Experts worldwide ranked by ideXlab platform
Feng Fan - One of the best experts on this subject based on the ideXlab platform.
-
mechanical performance of an improved semi Rigid Joint system under bending and axial forces for aluminum single layer reticulated shells
Thin-walled Structures, 2019Co-Authors: Feng FanAbstract:Abstract In this study, the traditional Temcor Joint (TR-Temcor) is modified using a central hollow hexagonal prism and some front bolts. The Finite Element Analysis (FEA) model is established and verified by experiments. Then, a parametric analysis is carried out for the improved Temcor Joint (IM-Temcor). To obtain the optimal parameters for the modified Joint, the key factors, namely: number and location of the front bolts, bolt-hole deviation, pretension force in bolts, thickness of front plate and heat-affected zone caused by the welding work, are considered in the FEA models. The modified Joint, with the optimized factors, is analyzed for different static load conditions, considering axial pressure, axial tension, pure bending, bending with axial force, and eccentric axial forces. The overall mechanical behavior of the Joint, including the M-Φ curves, initial stiffness, ultimate strength and deformation capacity, as well as the failure modes are identified. The results from the improved Joint are compared with corresponding values from of the traditional Temcor Joints. The results show that the central hollow hexagonal prism and front bolts significantly improves the stiffness and ultimate strength of the Joint, especially when the Joint is subjected to pure bending, bending with shear force, axial force, bending with certain axial force and eccentric force.
-
Dynamic behaviour and seismic design method of a single-layer reticulated shell with semi-Rigid Joints
Thin-Walled Structures, 2017Co-Authors: Zhi-wei Shan, Feng FanAbstract:Abstract Most of the existing studies on reticulated shells with a semi-Rigid Joint system have been focused on the mechanical properties under static loads. Taking material and geometric nonlinearities into account, the finite element analysis (FEA) model of a single-layer reticulated shell with semi-Rigid Joints was established using the software ABAQUS and then validated through comparison with the experimental result. Based on the bending stiffness of a bolt-column (BC) Joint obtained through experiments, the dynamic behaviour and a seismic design method for single-layer reticulated shells with semi-Rigid Joints were investigated in this paper. First, analysis of the free vibration frequency of the single-layer latticed domes with semi-Rigid bolt-column (BC) Joints was conducted based on several different parameters, including Joint stiffness, ratio of rise to span, initial geometric imperfection. Second, the seismic internal force coefficient of the members of the semi-Rigidly Jointed spherical single-layer reticulated shells of different parameters was studied in detail. Finally, the seismic internal force coefficients for spherical single-layer reticulated shells with semi-Rigid Joints under a common earthquake were derived.
-
experimental and numerical research on a new semi Rigid Joint for single layer reticulated structures
Engineering Structures, 2016Co-Authors: Shan Ren, Feng FanAbstract:Abstract Recent challenge for large-span single-layer reticulated structures is the development of a new Joint that can provide these structures with adequate stiffness while satisfying various important requirements, such as easy assembly on a construction site. In this paper, a new semi-Rigid Joint system, which is referred to as the bolt-column (BC) Joint, is developed. A series of tests was performed considering different thicknesses of the side plates, pretension forces and diameters of the bolts. A three-dimensional finite element (FE) model of the Joint was developed to evaluate the bending stiffness, moment resistance, rotational capacity and failure mode of the Joint. A comparison between the computations and experiments highlights the degree of accuracy of the proposed FE models. The moment-rotation curves, which can be introduced in the analysis of the structure, were obtained. The stiffnesses, strengths, rotation behaviours, and failure modes of the Joints are carefully compared and discussed. Based on the results, the influence rules of the parameters on the mechanical behaviour of the new Joint are obtained, which are helpful for engineers and designers. The results indicate that the application of this type of Joint in construction practice is promising. The experimental results are employed to calibrate the finite element models, which are used to conduct a parametric study.
-
Numerical analyses of semi-Rigid Joints subjected to bending with and without axial force
Journal of Constructional Steel Research, 2013Co-Authors: Feng Fan, Zhenggang Cao, Gengbo Chen, Shizhao ShenAbstract:Abstract Socket Joint systems are typical semi-Rigid Joints used in space structures. This paper presents numerical analyses of semi-Rigid Joint systems in which the bolts are pretensioned. Eleven numerical models of socket Joints are studied: three of them are subjected to bending and the others are subjected to proportional bending and axial compression. Moment–rotation relationships of the Joints are obtained using models in which the material and geometric nonlinearity are taken into account. The load-carrying mechanism of socket Joint system is investigated in detail through the numerical analysis. Through comparison of the finite element analysis (FEA) and corresponding test measurements, it is shown that the proposed FEA models can be used effectively to describe the mechanical performance of the semi-Rigid Joints in spatial structures, including the initial bending stiffness, ultimate bending moment, deformation and the failure mode.
-
Seismic Behaviour and Seismic Design of Single-Layer Reticulated Shells with Semi-Rigid Joint System
Advances in Structural Engineering, 2012Co-Authors: Feng Fan, Minling Wang, Zhenggang Cao, Shizhao ShenAbstract:An investigation of the seismic behaviour and a design method for single-layer reticulated shells with semi-Rigid Joints is described in this paper. A semi-Rigid Joint system has some bending and rotational Rigidity that lying between that of a Rigid-Joint and a pin-Joint. The seismic capacity of Kiewit reticulated shells with bolt-ball Joints is analyzed in detail on the basis of the bending Rigidity of the bolt-ball Joint reported by others. The change rules of natural frequency and seismic internal force coefficient are reviewed by analyzing of large-scale shells with different span, depth-to-span ratio, bending Rigidity, roof load, section size of members and seismic wave parameters. The seismic internal force coefficient (under the influence of bending moment) for shells with a semi-Rigid Joint system is summarized statistically to provide the maximal seismic response envelop.
Chen Fang - One of the best experts on this subject based on the ideXlab platform.
-
Performance study on T-stub connected semi-Rigid Joint between rectangular tubular columns and H-shaped steel beams
Frontiers of Structural and Civil Engineering, 2013Co-Authors: Chen FangAbstract:This paper investigates the performance of T-stub connected semi-Rigid Joint of rectangular tubular columns and H-shaped steel beams. The finite element analysis software ABAQUS is used to analyze the nonlinear performance of the Joint under monotonic loading. Meanwhile, the dimensions of T-stub, column and beam are considered as analytic parameters to discuss the performance of the Joint. The analysis shows that the thickness and the length of T-stub webs, the height of beam section, bolt diameter, shear connector and the preloaded force affect the performance of the Joint largely, and the thickness of the steel tube, the thickness and length of T-stub flange, bolt spacing have relatively little influences on the performance of the Joint. The research results indicate that this Joint is semi-Rigid Joint.
Shizhao Shen - One of the best experts on this subject based on the ideXlab platform.
-
Numerical analyses of semi-Rigid Joints subjected to bending with and without axial force
Journal of Constructional Steel Research, 2013Co-Authors: Feng Fan, Zhenggang Cao, Gengbo Chen, Shizhao ShenAbstract:Abstract Socket Joint systems are typical semi-Rigid Joints used in space structures. This paper presents numerical analyses of semi-Rigid Joint systems in which the bolts are pretensioned. Eleven numerical models of socket Joints are studied: three of them are subjected to bending and the others are subjected to proportional bending and axial compression. Moment–rotation relationships of the Joints are obtained using models in which the material and geometric nonlinearity are taken into account. The load-carrying mechanism of socket Joint system is investigated in detail through the numerical analysis. Through comparison of the finite element analysis (FEA) and corresponding test measurements, it is shown that the proposed FEA models can be used effectively to describe the mechanical performance of the semi-Rigid Joints in spatial structures, including the initial bending stiffness, ultimate bending moment, deformation and the failure mode.
-
Seismic Behaviour and Seismic Design of Single-Layer Reticulated Shells with Semi-Rigid Joint System
Advances in Structural Engineering, 2012Co-Authors: Feng Fan, Minling Wang, Zhenggang Cao, Shizhao ShenAbstract:An investigation of the seismic behaviour and a design method for single-layer reticulated shells with semi-Rigid Joints is described in this paper. A semi-Rigid Joint system has some bending and rotational Rigidity that lying between that of a Rigid-Joint and a pin-Joint. The seismic capacity of Kiewit reticulated shells with bolt-ball Joints is analyzed in detail on the basis of the bending Rigidity of the bolt-ball Joint reported by others. The change rules of natural frequency and seismic internal force coefficient are reviewed by analyzing of large-scale shells with different span, depth-to-span ratio, bending Rigidity, roof load, section size of members and seismic wave parameters. The seismic internal force coefficient (under the influence of bending moment) for shells with a semi-Rigid Joint system is summarized statistically to provide the maximal seismic response envelop.
-
Experimental study of semi-Rigid Joint systems subjected to bending with and without axial force
Journal of Constructional Steel Research, 2012Co-Authors: Feng Fan, Gengbo Chen, Shizhao ShenAbstract:Abstract Socket Joints and bolt-ball Joints are typical semi-Rigid Joint systems widely used in spatial structures. In this paper, tests on fifteen Joints are carried out to study their mechanical behavior. Three socket Joint systems are subjected to bending moment and shear force, and another seven socket Joint systems and five bolt-ball Joint systems are subjected to bending moment, shear force and axial compressive force. The main characteristics of the moment–rotation relationship for the connections under different loading schemes are summarized and discussed. The results indicate that: (i) both socket and bolt-ball Joint systems have good bending stiffness; (ii) the axial compressive force increases the initial bending stiffness of the Joints; (iii) the axial compressive force has different effects on the bending moment capacity of different Joints; and (iv) the yield process of moment–rotation curves of the Joints is shortened due to the action of the axial compressive force.
Pizhong Qiao - One of the best experts on this subject based on the ideXlab platform.
-
Mixed mode fracture characterization of GFRP-concrete bonded interface using four-point single leg bending test
Engineering Structures, 2018Co-Authors: Pizhong Qiao, Linjun LuAbstract:Abstract A combined analytical and experimental study using a single leg bending specimen under four-point bend loading is conducted to characterize mixed mode fracture of glass fiber reinforced polymer (GFRP)-concrete bonded interface. Both the conventional composite (Rigid Joint) and interface deformable (flexible Joint) bi-layer beam theories are used to calculate the compliance and energy release rate (ERR) of the proposed four-point single leg bending (4-SLB) specimens which are compared with and verified by the numerical finite element results. The results show that the flexible Joint model results in more accurate compliance and ERR compared with the conventional composite bi-layer beam theory for the 4-SLB specimen due to the attribute of crack tip deformation. The calculated ERR by the flexible Joint model can be reduced to that of the Rigid Joint one when the specimen is properly sized. Then, the designed 4-SLB specimens are utilized to measure the fracture toughness of GFRP-concrete bonded interface. To overcome the obstacle of low tensile strength of concrete and prevent the concrete substrate from premature fracture before the crack propagation of GFRP-concrete bonded interface takes place, the steel bars are used to reinforce the concrete substrate beams and a reduced section scheme at the interface is adopted. An aluminum beam is bonded to the thin GFRP plate so as to obtain different fracture mode ratios. The fracture toughness values of GFRP-concrete bonded interface under two different fracture mode ratios are obtained. The proposed 4-SLB specimen and data reduction procedures for the interface fracture toughness evaluation can be used to effectively characterize mixed mode fracture of hybrid material bonded interfaces.
-
Mixed mode fracture characterization of GFRP-concrete bonded interface using four-point asymmetric end-notched flexure test
Theoretical and Applied Fracture Mechanics, 2017Co-Authors: Pizhong QiaoAbstract:Abstract A combined analytical and experimental study using an asymmetric end-notched flexure specimen under four-point bend loading is conducted to characterize the fracture of glass fiber reinforced polymer (GFRP)-concrete bonded interface. Both the classic composite (Rigid Joint) and interface deformable (flexible Joint) bi-layer beam models are used to calculate the compliance and energy release rate (ERR) of the proposed four-point asymmetric end-notched flexure (4-AENF) specimen. The validity and accuracy of the models are obtained by comparison with the numerical finite element results. The results show that the flexible Joint model predicts more accurately the compliance and ERR compared with those of Rigid Joint model in 4-AENF specimen due to the attribute of crack tip deformation. Moreover, the calculated ERR by the flexible Joint model can be reduced to that of the Rigid Joint one when the specimen is properly sized. Then, the designed 4-AENF specimens are utilized to characterize the fracture toughness of GFRP-concrete bonded interface. To overcome the obstacle of low tensile strength and cracking behavior of concrete and prevent the premature fracture of concrete substrate before debonding of bonded interface takes place, a reduced section scheme is adopted and the steel bars are used to reinforce the concrete substrate beams. An aluminum beam with different thickness is bonded to the thin GFRP layer so as to change the stiffness of the composite GFRP/aluminum substrate, resulting in different fracture mode mixities. The fracture toughness values of GFRP-concrete bonded interface under three different mode ratios are obtained. The proposed 4-AENF specimen and data reduction procedures for interface fracture toughness evaluation can be used to effectively characterize mixed mode and mode-II dominated fracture of hybrid material bonded interface.
-
Buckling of delaminated bi-layer beam-columns
International Journal of Solids and Structures, 2011Co-Authors: Fangliang Chen, Pizhong QiaoAbstract:Abstract An improved analytical model is presented to analyze the delamination buckling of a bi-layer beam-column with a through-the-width delamination. Both the transverse shear deformation and local delamination tip deformations are taken into consideration, and two delaminated sub-layers as well as two substrates in the intact (un-delaminated) regions are modeled as individual Timoshenko beams. A deformable interface is introduced to establish the continuity condition between the two substrates in the intact regions. Consequently, a flexible Joint is formed at the delamination tip, and it is different from the conventional Rigid Joint given in most of studies in the literature, in which the local delamination tip deformations are completely ignored. In contrast to the local delamination buckling in our previous study ( Qiao et al., 2010 ), the present model accounts for the global deformations of the intact region in the delaminated composite beam-column, thus capable of capturing the buckling mode shape transitions from the global, to global–local coexistent, and to local buckling for asymmetric delamination as the interface delamination increases. Good agreement of the present analytical solutions with the full 2-D elastic finite element analysis demonstrates the local deformation effects around the delamination tip and verifies the accuracy of the present model. Parametric studies are conducted to investigate the effects of loading eccentricity, delaminated sub-layer thickness ratio, and interface compliance on the critical buckling load for the delaminated composite beam-column. Transitions of buckling modes from the global to local delamination buckling are also disclosed as the thickness of one sub-layer reduces from the thick sub-layer to a thin film. The developed delamination buckling solution facilitates the design analysis and optimization of laminated composite structures, and it can be used with confidence in buckling analysis of delaminated composite structures.
-
Fracture characterization of Carbon fiber-reinforced polymer-concrete bonded interfaces under four-point bending
Engineering Fracture Mechanics, 2011Co-Authors: Pizhong Qiao, Fangliang Chen, Lei Zhang, Ying Chen, Luyang ShanAbstract:Abstract A combined analytical and experimental approach is presented to characterize both mode-II and mixed mode fracture of Carbon fiber-reinforced polymer-concrete bonded interfaces under four-point bending load, and closed-form solutions of compliance and energy release rate of the mode-II (four-point symmetric end-notched flexure) and mixed (four-point asymmetric end-notched flexure) mode fracture specimens are provided. The transverse shear deformation in each sub-layer of bi-material bonded beams is included by modeling each sub-layer as an individual first order shear deformable beam, and the effect of interface crack tip deformation on the compliance and energy release rate are taken into account by applying the interface deformable bi-layer beam theory (i.e., the flexible Joint model). The improved accuracy of the present analytical solutions for both the compliance and energy release rate is illustrated by comparing with the solutions predicted by the conventional Rigid Joint model and finite element analysis. The fracture of Carbon fiber-reinforced polymer-concrete bonded interface is experimentally evaluated using both the four-point symmetric and asymmetric end-notched flexure specimens, and the corresponding values of critical energy release rates are obtained. Comparisons of the compliance rate-changes and resulting critical energy release rates based on the Rigid Joint model, the present theoretical model, and numerical finite element analysis demonstrate that the crack tip deformation plays an important role in accurately characterizing the mixed mode fracture toughness of hybrid material bonded interfaces under four-point bending load. The improved solution of energy release rates for the four-point symmetric and asymmetric end-notched flexure specimens by the flexible Joint model can be used to effectively characterize hybrid material interface, and the fracture toughness values obtained for the Carbon fiber-reinforced polymer-concrete interface under mode-II and mixed mode loading can be employed to predict the interface fracture load of concrete structures strengthened with composites.
-
Analysis of beam-type fracture specimens with crack-tip deformation
International Journal of Fracture, 2005Co-Authors: Jialai Wang, Pizhong QiaoAbstract:A novel bi-layer beam model is developed to account for local effects at the crack tip of a bimaterial interface by modeling a bi-layer composite beam as two separate shear deformable beams. The effect of interface stresses on the deformations of sub-layers, which is referred to as the elastic foundation effect in the literature, is considered in this model by introducing two interface compliance coefficients; thus a flexible Joint condition at the crack tip is considered in contrast to the “Rigid Joint” condition used in the conventional bi-layer model. An elastic crack tip deformable model is presented, and the closed-form solutions of local deformation at the crack tip are then obtained. By applying this novel crack tip deformation model, the new terms due to the local deformations at the crack tip, which are missing in the conventional composite beam solutions of compliance and energy release rate (ERR) of beam-type fracture specimens, are recovered. Several commonly used beam-type fracture specimens are examined under the new light of the present model, and the improved solutions for ERR and mode mixity are thus obtained. A remarkable agreement achieved between the present and available solutions illustrates the validity of the present study. The significance of local deformation at the crack tip is demonstrated, and the improved solutions developed in this study provide highly accurate predictions of fracture properties which can actually substitute the full continuum elasticity analysis such as the finite element analysis. The new and improved formulas derived for several specimens provide better prediction of ERR and mode mixity of beam-type fracture experiments.
Gerald R. Frederick - One of the best experts on this subject based on the ideXlab platform.
-
Analysis of frames with semi-Rigid Joints
Computers & Structures, 1994Co-Authors: O.a. Abu-yasein, Gerald R. FrederickAbstract:Abstract This paper presents a method to determine the load capacity as well as end member forces and deformations of frames with partial Rigid Joint connections by using the direct stiffness method. The connections are modeled as rotational springs attached at the ends of framed members.
