Composite Steel- concrete Frame Beam with Reinforced Negative Bending Regions

Considering the large negative bending moment at the end of frame beam and low tensile strength of concrete,a new composite steel-concrete frame beam(CSCFB),reinforced by a T shape steel beam at the negative bending regions,was brought forward.Through two full-scale of single-layer CSCFB frame models experiment,the load-displacement curves of CSCFB and strain distribution at cross section were obtained.Compared with the ordinary composite beam,the T shape reinforcing section can enhance the beam stiffness effectively,and make it distribute reasonably.The segment flexural rigidity method is presented and validated.     

Experimental Analysis for Steel Box Concrete Composite Beam of Arch Bridge

A new steel concrete composite structure was proposed which composed of steel box beam, PC beam and PBH Shear connection. Bend test was carried out for the performance study of deformation and stress. It was found that Material advantages of steel and concrete were fully used and crack of concrete and local instability of steel box were avoided. And the deformation between steel box and concrete can be smoothed with PBH shear connection. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the practice analysis. With the different parameters analysis, mechanic performance of the composite was obtained.     

Hysteretic Behavior of Composite Deep Beam Infilled Steel Frame

The Quasi static tests of one steel frame and two the composite deep beams infilled steel frames were carried out. The effects of the deep beams on the load capacity, ductility, hysteretic property and energy dissipation of pure steel structure were analyzed. It is found that the hysteresis curve is a straight line with the constant of the stiffness at the beginning and without residual deformation. And the hysteresis curve of specimen was full after yielding, and the skeleton curves had a clear plastic flow phase with triple linear. The lateral drifts of the beam specimens at failure were 1/25 and 1/22. The composite deep beams enhance the initial stiffness, yield load and maximum load bearing capacity of steel frame. Therefore, seismic performance of the composite deep beams is better.     

Experimental Analysis of the Behavior of Steel Plate-masonry Composite Wall-beams

When steel plate-masonry composite structure used in the existing masonry structure with load bearing walls is removed for a large space, composite action should be considered between the beam and the supported masonry wall due to the arch effect formed in the supported wall. In order to investigate the working mechanism, failure mode, and load-carrying capacity, strain distribution in critical sections and mid-span defcection of this type of composite wall-beam, five steel plate-masonry wall-beams were tested under concentrated loads and analyzed, which considered variables of height-span-ratio of supported masonry wall, height-span-ratio of composite beam and thickness of steel plate. The results show that steel plate-masonry composite wall-beam starts failure from the masonry located at the line between loading point and supporting point; strain distribution of steel plate along section height meets the plane section assumption; the height-span-ratio of supported wall can directly influence the failure mode of masonry wall, buckling load corresponding to steel plate experiencing local buckling and ultimate load of tested specimens; the reasonable height of supported masonry wall is beneficial to the formation of composite action between supported masonry wall and composite beam, and the excessive high masonry wall will reduce the ultimate load of the tested specimen. Finally, the reasonable range for height-span-ratio of supported masonry wall was presented, and the proposed value representing the flexural stiffness of the steel plate-composite beam relative to the in-plane stiffness of the supported masonry wall was at least more than 79.     

Experimental Analysis on Beam-column Behavior of Steel-concrete Composite Pylon

Ten specimens with perforated ribs, which can be divided into two series, were made to observe the behavior of steel-concrete composite pylon under axial load and cyclic load respectively. The experiment reveals the ultimate capacity and failure mode of two types of specimens under the cyclic load with different actual axial load level. Furthermore, it can be concluded from the results that the failure mode can be divided into two types, that is compression failure and tension failure. And the behavior of those specimens under cyclic load is influenced significantly under high axial load or without axial load at all. In addition, perforated ribs will prevent the plates under compression from overall buckling effectively based on the observation that the wavelength of plate is limited between two neighboring perforated ribs. At last, comparison on the interaction behaviors of the axial load (N) versus moment (M) is made between the results of experiment and calculation according to the criteria.     

Bearing Capacity of Reinforced Concrete Continuous Deep Beams with Web Openings Based on ANSYS Analysis

Based on the experiment on two-span continuous deep beams with web openings bearing concentrated load, setting a series of finite element simulation specimens and establishing finite element model by finite element analysis software ANSYS, the influences of the strength of concrete, the open hole size, the hole position, vertical reinforcement ratio and horizontal reinforcement ratio on bearing capacity and deflection of specimens were contrasted when imposed respectively.     

Mechanical Behavior and Techno economic Analysis of Twice prestressed Simply Supported Composite Beam

Excessive creep camber of prestressed concrete bridge would result in risk on the traffic safety in high speed railway. To control creep camber of presstressed concrete bridge, a new twice prestressed technology was proposed to presstressed concrete beam. Four twice prestressed simply supported box girders with different prestressed degrees were designed as an example. Its section stress, strength and crack resistance in different construction stages were analyzed. Compared the creep camber between conventional prestressed simply supported concrete beam and twice prestressed simply supported composite beam with the same prestressed steels, it was shown that twice prestressed composite beam has a smaller stress gradient. And the creep camber decreased approximately 40% to 60% with building height reduction, as well as some 10% energy saving and some amount of concrete.     

Experimental Analysis on Bending Capacity of Unbonded Prestressed Concrete Beams with HRBF500 Steel Bars

The bending capacity tests on ten simple supported beams were conducted to investigate the damage characteristics, prestress increment, beading capacity and displacement ductility of unbounded prestressed concrete beams with HRBF500 steel bars. The results show that the HRBF500 steel bars has yielded before the limit state. The concrete in compression zone crushes upon the broken of the beams, which shows a sudden damage mode. The measured ultimate stress increments of unbounded tendons are in linear relationship with the comprehensive reinforcement ratio index, while the values of the ultimate stress increments are obviously higher than those values specified in the code GB50010-2010, and the average ratio of predicted values to testing values is about 0.35. The mid span deflection upon yielding of the beams is large, while the displacement ductility is bad and the average value of the displacement ductility ratio is 1.67. The displacement ductility ratio decreases with the increases of the comprehensive reinforcement ratio index. Based on the experimental results, the proposed calculation formula of ultimate stress increments of unbounded tendons was established, and it is in good agreement with the experimental results when the testing value is less than 450 MPa.     

Experimental Analysis of Time-dependent Shear Behavior on Stud Connectors

With regard to the long span continuous composite beams, the early composite shear stud strength at the joint surface between the steel girder and concrete slab at different concrete ages should be considered while the concrete slabs are casted by phases in construction stage. In this study, the push-out test of stud shear connectors were conduced at different concrete ages. Meanwhile, the change law of the ultimate shear strength, ultimate slip deformation, design shear strength, and shear stiffness of the stud shear connectors with concrete ages were analyzed, and the corresponding time-dependent calculation equations were presented. The results include that the main failure modes of stud shear connectors are the concrete slab splitting failure before 3-days concrete age. The load-slip laws of stud shear connectors at different concrete ages are basically the same, however, the shear strength and stiffness all increase with the concrete ages prolonging, and the increase degree is faster at early ages, but slower at later ages, which indicates that the early composite shear stud strength at the joint surface of composite beams should not be neglected.     

Theoretical and Experimental Study on the Deformation of Pipe Rotary-draw Bending

Deformation of pipe during rotary-draw bending is studied theoretically and experimentally.The effect of main technical parameters on the change of wall thickness and section flattening are analyzed with plastic FEM software,meanwhile the variety of wall thickness and section flattening in different location of pipe are studied experimentally.The result shows: the smaller R/D,the bigger the wall thickness change.The effect of t/D on wall thickness change is weak.The dimension and position of the mandrel have a big impact on wall thickness and section flattening.The conclusion is helpful to improve the quality of the rotary-draw bending of pipe.     

Experimental Study on Flexural Behavior of Reinforced Concrete Beams Strengthened With Ferrocement Mortar

Experimental research on flexural behavior of the different grade RC beams strengthened with ferrocement mortar through six RC beams is carried out. The matching of original component concrete to the composite mortar strength rank is studied and its influence on bending strength, the crack-resisting capacity and the bending stiffness of RC beams is analyzed. Based on plane cross-section assumption and the experimental results, the formulas of the theoretical ultimate strength capacity and stiffness are brought forward. The calculated results fit well with the experimental results, to provide a theoretical reference for actual engineering designs.     

Finite Element Analysis of Shear Behavior of Super High Strength Reinforced Concrete Beam

On the basis of testing results of shear behavior from 18 super high strength reinforced concrete restrained beams with web reinforcement, with the cube compressive strength ranging from over 100Mpa, in this paper, the nonlinear finite element analysis procedure was formulated and the analysis of the specimen tests was carried out with the parameters obtained from the experiments and improved constitutive model and failure criteria of materials. Based on the simulated shear resistance test results and practical measured data of eighteen super high strength concrete restrained beams under point load, the equation to compute the shear resistance capacity of such beams was thus obtained by regression. The analytical results agree well with those of experiments.     

Experimental Analysis of Cracking Behavior of ConcreteBeams Reinforced with High Strength Bars

Eight concrete beams reinforced with 500MPa steel bars and four reinforced with 400MPa ultra fine grain steel bars were tested under two point symmetrical concentrated static loading to observe the details of crack pattern development on these beams and investigate their cracking characteristics. It was shown that the cracking behavior of the beams with high strength bars was essentially similar to that of common RC flexural members, whereas the computed crack widths using the formula adopted in the Code for Design of Concrete Structures GB 50010 2002 exceeded that of the experiment under the normal service. Furthermore, the formulas for crack spacing and crack width specified in GB 50010 2002 were evaluated through the experimental results and previous studies of sixty seven concrete beams reinforced with high strength bars. On the basis of the calculation model in GB 50010 2002, revised formulas for crack spacing and crack width were proposed. The values calculated by revised formulas were in good agreement with the test results.     

Study on Effect of Longitudinal Reinforcement Ratio on Shear Behavior of Restrained Beams with Web Reinforcement

In this paper, five restrained beams with web and different longitudinal reinforcement ratio as well as above longitudinal reinforcement truncated were tested under static point loads. On this basis, the overall process of cracking development under shear and the effect of longitudinal reinforcement ratio on shear strength was investigated     

Design Approach on Flexural Load-carrying Capacity of Steel Beam to CFST Column Joints with External Stiffening Ring

A 3-D finite element model is established by ABAQUS to simulate the behavior of the joints with concrete-filled steel tubular (CFST) column to steel beam using external stiffening ring.The load versus deformation curves of this type of joints are compared between theoretical and experimental results,and in good agreement.Parametric analysis is performed to study the flexural load-carrying capacity of the joint.The width of external stiffening ring,the steel ratio of CFST column,the ultimate strength of steel beam,the strength of steel tube and beam,the concrete strength,the axial load ratio,and the beam to column linear stiffness ratio are considered as parameters.The simplified practical design approach is proposed based on parameter analysis of the flexural load-carrying capacity of these joints.The practical calculated values are in good agreement with the FEM results.     

Experimental Investigation of "Column with Weaker Beam" Frame and "Column with Equally Strong Beam" Frame

By the way of experiment and analysis of two "one story and one bay" reinforced concrete frames, namely a "beam with weaker column" frame and a "column with equally strong beam" frame, the features of internal force redistribution are investigated and an elementary comparison about bending moment redistribution of three kinds of frames namely the "column with weaker beam", "beam with weaker column" and "column with equally strong beam" is given. Through this comparison, the objective existence of such "three kinds of frame" is proven, the moment redistribution is different for each frame and for the moment modulation, the elastic moment diagram and the difference of the internal force redistribution in different frames should be considered together.     

Experiment and FEM Analysis on the Joint of Inserted Steel Beam

A new composite structure which is composed of steel beam and concrete girder is introduced in fuel electric plant construction. With different height of concrete girders with or without anchor bar, two scale models from an actual project were designed and tested. It is shown that the maximum restraining moment of ends of steel beams is approximately 60kN*m; influence of anchor bar is little; the one with 600mm high concrete beam is damaged by shear, and the others steel beam is damaged by bending failure. Finite element models were built for supplementary analysis, and the result indicates that critical value of the height of concrete beam of different failure modes is 700mm; stiffness of shear key and thickness of floor have great influence on the structure; size of anchor bar has little influence; and width of the end of the steel beam has certain influence.     

Elastic-Plastic Analysis of Bolt-Group Connections Subject to shear and Bending Forces

In this paper,a shear-deformation nonlinear relationship of single bolted connection subject to shear forces is determined by curve-fitting to experimental data and this nonlinear relationship is directly applied to force-deformation calculation of bolt-group connections subject to shear and bending forces. Elastic-plastic analysis of bolt-group connections subject to shear and bending forces is performed on the basis of ultimate design concept.The analytical results are checked against the experimental results and a satisfactory agreement is obtained.     

Experimental and Parametric Analysis of the Flexural Behavior of HRBF RC Beams

In order to investigate the flexural behavior of concrete beams reinforced with high strength hot rolled bars of fine grains, static bending test on four rectangle cross section HRBF400, HRBF500 RC beams was conducted. The results show that the experimental maximum crack width under short term load meets the requirement of current code while calculated value does not meet; mid span deflection of RC beams with HRBF400 under short term load still meets the requirement of current code while RC beams with HRBF500 does not meet. Bearing capacity calculating formula under conditions of crack/deflection control was proposed and conception of component's bearing capacity utilization coefficient (BCUC) was put forward. The influences of reinforcement strength, reinforcement diameter, concrete grade, reinforcement ratio, concrete cover thickness and high span ratio on BCUC were analyzed. Within the range of economic reinforcement ratio, ductility of HRBF RC beams meets the requirement. Energy dissipation capacity of HRBF RC beams is similar to that of normal RC beams at low reinforcement ratio but it decreases faster than normal RC beams with the increasing of reinforcement ratio. Energy dissipation capacity of HRBF RC beams is higher than that of normal RC concrete beams in elastic stage and it enhances with the increasing of reinforcement ratio.     

Experimental Analysis of Simply-Supported Concrete Box Girder with Web Openings model Under Double Uniformly Distributed Load

In order to satisfy the demand of the double-deck traffic in city, a concrete box girder model with rectangular web openings was designed with ratio of 1:6. Experimental study was carried out to investigate the flexural capacity of the model girder with double uniformly distributed load. The finite element model was established based on the experiment and the results agreed with measurement results. The effect of the web openings on the girder was explored. The results demonstrated that the deflection caused by load on bottom plate of box girder was 9.7% more than that of load on the top plate. The deflection of girder with web opening is 22.9%~28.1% greater than that of girder without web opening. Compared with girder without web opening, the shear lag of girder with web opening increased, of which the maximum value was 62.0% in various working conditions. simply-supported concrete box girder with web openings under double uniformly distributed load affect the flexural capacity.