The cover beam refers to the load of the upper building structure in order to support, distribution and transmission, the beam can also be designed at the top of the vase pier. The construction quality of the cover be...The cover beam refers to the load of the upper building structure in order to support, distribution and transmission, the beam can also be designed at the top of the vase pier. The construction quality of the cover beam directly affects the quality of the bridge. In this paper, the construction process of a semi-inverted T-type invisible cover beam is combined with a project to summarize its construction technology. In order to control the construction quality of the cover beam, the reference basis is provided for the construction of half inverted T-shaped invisible cover beam in the future.展开更多
In order to study influences of geometric parameters on the T-shaped components local loading process, a new mathematical model considering the fillet radius and draft angle was established by using the slab method. T...In order to study influences of geometric parameters on the T-shaped components local loading process, a new mathematical model considering the fillet radius and draft angle was established by using the slab method. The results obtained by the mathematical model agree with the data form experiment and numerical simulation, and the results are closer to the experimental and simulation results. The influence of draft angle may be neglected under the forming conditions used. The influence of fillet radius is notable, especially in the case that the ratio of fillet radius to rib width is less than 0.75.展开更多
Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface...Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.展开更多
A self-aligned InP/GalnAs single heterojunction bipolar transistor（HBT） is investigated using a novel T-shaped emitter. A U-shaped emitter layout,selective wet etching,laterally etched undercut, and an air-bridge ar...A self-aligned InP/GalnAs single heterojunction bipolar transistor（HBT） is investigated using a novel T-shaped emitter. A U-shaped emitter layout,selective wet etching,laterally etched undercut, and an air-bridge are applied in this process. The device, which has a 2μm×12μm U-shaped emitter area,demonstrates a common-emitter DC current gain of 170,an offset voltage of 0.2V,a knee voltage of 0.5V, and an open-base breakdown voltage of over 2V. The HBT exhibits good microwave performance with a current gain cutoff frequency of 85GHz and a maximum oscillation frequency of 72GHz, These results indicate that these InP/InGaAs SHBTs are suitable for low-voltage,low-power,and high-frequency applications.展开更多
This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design metho...This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design method. Comparison of the design provisions of the GB 50011-2010 code and those of the American code ACI 318-14 indicates a possible deficiency in the T-shaped wall design provisions in GB 50011-2010. A case study of a typical T-shaped wall designed in accordance with GB 50011-2010 also indicates the insufficient extent of the boundary element at the non-flange end and overly conservative design of the flange end boundary element. Improved designs for special boundary elements ofT-shaped walls are developed using a displacement-based method. The proposed design formulas produce a longer boundary element at the non-flange end and a shorter boundary element at the flange end, relative to those of the GB 50011-2010 provisions. Extensive numerical analysis indicates that T-shaped walls designed using the proposed formulas develop inelastic drift of 0.01 for both cases of the flange in compression and in tension.展开更多
Through the investigation on traditional arc stud welding process, a new welding gun and its control system were developed in this paper. The stepping arc stud welding gun was mainly made by a stepping motor as actuat...Through the investigation on traditional arc stud welding process, a new welding gun and its control system were developed in this paper. The stepping arc stud welding gun was mainly made by a stepping motor as actuating unit and a screw-driven device as moving unit. A control system with a MCS-51 single-chip microcomputer as main control component was used to realize the new stud welding procedure. This new welding process with stepping stud welding gun is named as stepping arc stud welding. In the new welding process, the stud action can be looked as constituted by some micro steps. The setting and adjusting of the stepping arc welding gun behavior parameters are accomplished independently. It is indicated from the results of process tests and bending test that the stepping arc stud welding process is practicable.展开更多
Spur dike is one of the river training structures. This work presented a numerical simulation of flow field and three-dimensional velocity around a T-shaped spur dike located in bend using SSIIM model. The main object...Spur dike is one of the river training structures. This work presented a numerical simulation of flow field and three-dimensional velocity around a T-shaped spur dike located in bend using SSIIM model. The main objective of this work is to investigate the three-dimensional velocities and streamlines at transverse and longitudinal sections and plan views around the T-shaped spur dike in different submergence ratios(0, 5%, 15%, 25% and 50%). It is concluded that by increasing the submergence ratio from 5% to 50%, the maximum of scour is reduced; the maximum of longitudinal velocity increases by 7.7% and occurs at the water surface in spur dike axis. Near the bed, the maximum of vertical velocity occurs at the end of spur wing. By analyzing the streamlines at transverse sections, the followings were deduced for different submergence ratios: different dimensions and different positions of vortices around the spur dike.展开更多
An analytical procedure is presented to evaluate the fluid sloshing characteristics in a two-dimensional(2D)rectangular container with a bottom-mounted T-shaped baffle.The fluid region is divided into several sub-doma...An analytical procedure is presented to evaluate the fluid sloshing characteristics in a two-dimensional(2D)rectangular container with a bottom-mounted T-shaped baffle.The fluid region is divided into several sub-domains with hypothetical interfaces and the velocities and pressures of the fluid on adjacent interfaces should be identical.The separation of variables in conjunction with the superposition principle is employed to formulate the velocity potential of each sub-domain.The Fourier series expansion is used to derive the eigenvalue equation by substituting the velocity potential solutions into the free surface conditions and the continuity conditions on adjacent interfaces.Under the horizontal base excitation,the total velocity potential of fluid is decomposed of the impulsive and perturbed velocity potentials.The orthogonality of the sloshing modes is demonstrated by implementing Gauss formula.The dynamic response equation is established by incorporating the total velocity potential solution into the surface wave equation.Excellent agreements are achieved between the present results and those from the reported literature and finite element code.Numerical results are exhibited to reveal the effect of the baffle parameters and excitation frequency on sloshing characteristics and responses of liquid.展开更多
The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a ...The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a novel steel BRB is proposed. In this new-type steel BRB, two T-shaped steels are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. Meanwhile, the ingot-iron material with low yielding strength and high elongation is applied to the steel core to study the mechanical properties of steel BRBs. To validate the theoretical requirements for the width-to-thickness ratio of the steel core and the thickness of angle steel, quasi-static tests of eight specimens were conducted. The tests focused on the energy dissipation capacity and failure modes of the proposed steel BRBs. Nonlinear finite element analysis was also carried out to validate the experimental results. Both the aforementioned results imply that appropriately designed steel BRBs can meet the performance requirements for BRB components.展开更多
This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) mo...This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.展开更多
Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of opti...Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of optical microscopy （OM）, scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, and X-ray diffraction （XRD）. Results showed that 45 steel stud and 6061 aluminum alloy could be successfully joined by high frequency induction brazing with proper processing parameters. The bonding strength of the joint was of the order of 88 MPa. Ni coating on steel stud successfully avoided the generation of Fe-AI intermetallic compound which is brittle by blocking the contact between A1 and Fe. Intermetallic compounds, i e, AI3Ni2, AlmNi0.9 and A10.3Fe3Si0.7 presented in AI side, FeNi and Fe-A1-Ni ternary eutectic structure were formed in Fe side. The micro-hardness in intermetallic compound layer was 313 HV. The joint was brittle fractured in the intermetallic compounds layer of A1 side, where plenty of A13Ni2 intermetallie compounds were distributed continuously.展开更多
Aimed at two typical composite floor systems of through steel bridges in high speed railway,design methods of headed studs were put forward for different composite members through comparing and analyzing the structure...Aimed at two typical composite floor systems of through steel bridges in high speed railway,design methods of headed studs were put forward for different composite members through comparing and analyzing the structure,mechanical characteristics and transmission routes of deck loads.The simplified calculation models were brought out for the stud design of the longitudinal girders and transverse girders in the composite floor system of Nanjing Dashengguan Yangtze River Bridge (NDB).Studs were designed and arranged by taking the middle panel of 336 m main span for example.The results show that under deck loads,the longitudinal girders in the composite floor system of through steel bridges are in tension-bending state,longitudinal shear force on the interface is caused by both longitudinal force of "The first mechanical system" and vertical bending of "The second mechanical system",and studs can be arranged with equal space in terms of the shear force in range of 0.2d (where d is the panel length) on the top ends.Transverse girders in steel longitudinal and transverse girders-concrete slab composite deck are in compound-bending state,and out-of-plane bending has to be taken into account in the stud design.In orthotropic integral steel deck-concrete slab composite deck,out-of-plane bending of transverse girders is very small so that it can be neglected,and studs on the orthotropic integral steel deck can be arranged according to the structural requirements.The above design methods and simplified calculation models have been applied in the stud design of NDB.展开更多
文摘The cover beam refers to the load of the upper building structure in order to support, distribution and transmission, the beam can also be designed at the top of the vase pier. The construction quality of the cover beam directly affects the quality of the bridge. In this paper, the construction process of a semi-inverted T-type invisible cover beam is combined with a project to summarize its construction technology. In order to control the construction quality of the cover beam, the reference basis is provided for the construction of half inverted T-shaped invisible cover beam in the future.
基金Project (50935007) supported by the National Natural Science Foundation for Key Program of ChinaProject (2010CB731701) supported by the National Basic Research Program of ChinaProject (50905145) supported by the National Natural Science Foundation of China
文摘In order to study influences of geometric parameters on the T-shaped components local loading process, a new mathematical model considering the fillet radius and draft angle was established by using the slab method. The results obtained by the mathematical model agree with the data form experiment and numerical simulation, and the results are closer to the experimental and simulation results. The influence of draft angle may be neglected under the forming conditions used. The influence of fillet radius is notable, especially in the case that the ratio of fillet radius to rib width is less than 0.75.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20131261)
文摘Cold metal transfer （CMT） welding of nickel-coated Q235 steel studs with 606l Al alloy was carried out using ER4043 as filler metal. The welding process was stable, and appearance of weld formed well without surface defect under the parameters of welding current 121 A, welding voltage 15.4 V and welding speed 6 r/min. The microstructure of fiUer metal was analyzed by means of scanning electron microscopy. The filler metal and 6061 Al alloy were fused to form fusion welding interface, the fusion zone had a good bonding without any micro defect. The steel stud did not melt and brazing interface was formed between the filler metal and steel stud. Two different reaction layers existed in the brazing interface, the Fe2Al5 layer about 10 -12 p^m formed near the steel stud side, and the other layer was mainly composed of FeAl3. Nickel-rich zone was formed in the root toe area of the fillet weld, which was mainly composed of Al3Ni2. The tensile tests showed that the maximum shearing strength of the joints was 129 MPa. The joint was brittle fractured in the intermetallic compound layer where plenty of FeAl3 were distributed continuously.
文摘A self-aligned InP/GalnAs single heterojunction bipolar transistor（HBT） is investigated using a novel T-shaped emitter. A U-shaped emitter layout,selective wet etching,laterally etched undercut, and an air-bridge are applied in this process. The device, which has a 2μm×12μm U-shaped emitter area,demonstrates a common-emitter DC current gain of 170,an offset voltage of 0.2V,a knee voltage of 0.5V, and an open-base breakdown voltage of over 2V. The HBT exhibits good microwave performance with a current gain cutoff frequency of 85GHz and a maximum oscillation frequency of 72GHz, These results indicate that these InP/InGaAs SHBTs are suitable for low-voltage,low-power,and high-frequency applications.
基金International Science&Technology Cooperation Program of China under Grant No.2014DFA70950Tsinghua University Initiative Scientific Research Program under Grant No.2012THZ02-1National Natural Science Foundation of China under Grant No.91315301
文摘This study examines the design provisions of the Chinese GB 50011-2010 code for seismic design of buildings for the special boundary elements of T-shaped reinforced concrete walls and proposes an improved design method. Comparison of the design provisions of the GB 50011-2010 code and those of the American code ACI 318-14 indicates a possible deficiency in the T-shaped wall design provisions in GB 50011-2010. A case study of a typical T-shaped wall designed in accordance with GB 50011-2010 also indicates the insufficient extent of the boundary element at the non-flange end and overly conservative design of the flange end boundary element. Improved designs for special boundary elements ofT-shaped walls are developed using a displacement-based method. The proposed design formulas produce a longer boundary element at the non-flange end and a shorter boundary element at the flange end, relative to those of the GB 50011-2010 provisions. Extensive numerical analysis indicates that T-shaped walls designed using the proposed formulas develop inelastic drift of 0.01 for both cases of the flange in compression and in tension.
文摘Through the investigation on traditional arc stud welding process, a new welding gun and its control system were developed in this paper. The stepping arc stud welding gun was mainly made by a stepping motor as actuating unit and a screw-driven device as moving unit. A control system with a MCS-51 single-chip microcomputer as main control component was used to realize the new stud welding procedure. This new welding process with stepping stud welding gun is named as stepping arc stud welding. In the new welding process, the stud action can be looked as constituted by some micro steps. The setting and adjusting of the stepping arc welding gun behavior parameters are accomplished independently. It is indicated from the results of process tests and bending test that the stepping arc stud welding process is practicable.
文摘Spur dike is one of the river training structures. This work presented a numerical simulation of flow field and three-dimensional velocity around a T-shaped spur dike located in bend using SSIIM model. The main objective of this work is to investigate the three-dimensional velocities and streamlines at transverse and longitudinal sections and plan views around the T-shaped spur dike in different submergence ratios(0, 5%, 15%, 25% and 50%). It is concluded that by increasing the submergence ratio from 5% to 50%, the maximum of scour is reduced; the maximum of longitudinal velocity increases by 7.7% and occurs at the water surface in spur dike axis. Near the bed, the maximum of vertical velocity occurs at the end of spur wing. By analyzing the streamlines at transverse sections, the followings were deduced for different submergence ratios: different dimensions and different positions of vortices around the spur dike.
基金The study was financially supported by the National Natural Science Foundation of China(Grant No.51978336)the Science and Technology Project of Water Resources Department of Jiangsu Province(Grant No.2021022).
文摘An analytical procedure is presented to evaluate the fluid sloshing characteristics in a two-dimensional(2D)rectangular container with a bottom-mounted T-shaped baffle.The fluid region is divided into several sub-domains with hypothetical interfaces and the velocities and pressures of the fluid on adjacent interfaces should be identical.The separation of variables in conjunction with the superposition principle is employed to formulate the velocity potential of each sub-domain.The Fourier series expansion is used to derive the eigenvalue equation by substituting the velocity potential solutions into the free surface conditions and the continuity conditions on adjacent interfaces.Under the horizontal base excitation,the total velocity potential of fluid is decomposed of the impulsive and perturbed velocity potentials.The orthogonality of the sloshing modes is demonstrated by implementing Gauss formula.The dynamic response equation is established by incorporating the total velocity potential solution into the surface wave equation.Excellent agreements are achieved between the present results and those from the reported literature and finite element code.Numerical results are exhibited to reveal the effect of the baffle parameters and excitation frequency on sloshing characteristics and responses of liquid.
基金Supported by:Basic Research Foundation of Institute of Engineering Mechanics,CEA under Grant No.2017A01the Earthquake Scientific Research Funds Program under Grant No.201508023
文摘The rectangle core plate of all-steel buckling-restrained braces(BRBs) usually exhibit obvious local buckling, due to the lack of longitudinal restraint from the encasing tube. To eliminate the undesirable effects, a novel steel BRB is proposed. In this new-type steel BRB, two T-shaped steels are adopted as the minor restraint elements to restrain the core plate instead of infilled concrete or mortar. Meanwhile, the ingot-iron material with low yielding strength and high elongation is applied to the steel core to study the mechanical properties of steel BRBs. To validate the theoretical requirements for the width-to-thickness ratio of the steel core and the thickness of angle steel, quasi-static tests of eight specimens were conducted. The tests focused on the energy dissipation capacity and failure modes of the proposed steel BRBs. Nonlinear finite element analysis was also carried out to validate the experimental results. Both the aforementioned results imply that appropriately designed steel BRBs can meet the performance requirements for BRB components.
基金Project(2011BAJ09B02)supported by the National Key Technology R&D Program,ChinaProjects(51578548,51378511,51678576)supported by the National Natural Science Foundation of China
文摘This work experimentally investigates the effects of shear stud characteristics on the interface slippage of steel-concrete composite push-out specimens. ABAQUS is used to establish a detailed 3D finite element(FE) model and analyze the behavior of push-out specimens. The modeling results are in good agreement with the experimental results. Based on parametrical analysis using the validated FE approaches, the effects of important design parameters, such as the diameter, number, length to diameter ratio, and yield strength of studs, concrete strength and steel transverse reinforcement ratio, on the load-slip relationship at the interface of composite beams are discussed. In addition, a simplified approach to model studs is developed using virtual springs with an equivalent stiffness. This approach is demonstrated to be able to predict the load-displacement response and ultimate bearing capacity of steel-concrete composite beams. The predicted results show satisfactory agreement with experimental results from the literature.
基金Funded by the National Defense Basic Research Program(No.A2620110005)the Equipment Pre Research Project of Eleventh Five-Year Plan of China(No.40401050301)the Natural Science Foundation of Jiangsu Province(No.BK20131261)
文摘Nickel-coated 45 steel studs and 6061 aluminum alloy with 4047 A1 alloy foil as filler metal were joined by using high frequency induction brazing. The microstrueture of Fe/A1 brazed joint was studied by means of optical microscopy （OM）, scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, and X-ray diffraction （XRD）. Results showed that 45 steel stud and 6061 aluminum alloy could be successfully joined by high frequency induction brazing with proper processing parameters. The bonding strength of the joint was of the order of 88 MPa. Ni coating on steel stud successfully avoided the generation of Fe-AI intermetallic compound which is brittle by blocking the contact between A1 and Fe. Intermetallic compounds, i e, AI3Ni2, AlmNi0.9 and A10.3Fe3Si0.7 presented in AI side, FeNi and Fe-A1-Ni ternary eutectic structure were formed in Fe side. The micro-hardness in intermetallic compound layer was 313 HV. The joint was brittle fractured in the intermetallic compounds layer of A1 side, where plenty of A13Ni2 intermetallie compounds were distributed continuously.
基金Project(2004G016-B) supported by the Science and Technology Development Program of Railways Department,China
文摘Aimed at two typical composite floor systems of through steel bridges in high speed railway,design methods of headed studs were put forward for different composite members through comparing and analyzing the structure,mechanical characteristics and transmission routes of deck loads.The simplified calculation models were brought out for the stud design of the longitudinal girders and transverse girders in the composite floor system of Nanjing Dashengguan Yangtze River Bridge (NDB).Studs were designed and arranged by taking the middle panel of 336 m main span for example.The results show that under deck loads,the longitudinal girders in the composite floor system of through steel bridges are in tension-bending state,longitudinal shear force on the interface is caused by both longitudinal force of "The first mechanical system" and vertical bending of "The second mechanical system",and studs can be arranged with equal space in terms of the shear force in range of 0.2d (where d is the panel length) on the top ends.Transverse girders in steel longitudinal and transverse girders-concrete slab composite deck are in compound-bending state,and out-of-plane bending has to be taken into account in the stud design.In orthotropic integral steel deck-concrete slab composite deck,out-of-plane bending of transverse girders is very small so that it can be neglected,and studs on the orthotropic integral steel deck can be arranged according to the structural requirements.The above design methods and simplified calculation models have been applied in the stud design of NDB.
