60 publications from this institution
A fully non-linear finite element (FE) package has been used to examine the behaviour and design requirements for the transverse stiffeners of transversally stiffened webs in plate and box girder bridges. Initially the stiffeners were modelled as a nodal line support to study the shape and magnitude of the forces acting due to the destabilising effects of the buckling of web panels up to their ultimate capacity. Analyses were also carried out with various stiffener geometries to study the variation of web strength with stiffener size and the effects of the stiffener deflections. Analyses were undertaken on webs subjected to shear, bending and compression. A design method has been formulated based on a simple beam spanning between the top and bottom flanges of the girders. The design method is generally compatible with the clauses of BS 5400 Part 3. The paper compares the resulting design requirements with those of the British Code. (A) For the covering abstract see IRRD 869077.
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The 1994 CSA-A23.3 standard "Design of concrete structures" includes a new shear design method based on the equations of the modified compression field theory (MCFT). This "general method" is a simplification which casts the MCFT in the traditional "V c + V s " format resulting in a set of six general equations and two tables. This new method unifies the treatment of reinforced, partially prestressed and fully prestressed concrete and accounts, in a rational manner, for the effects of axial load and bending moment on shear capacity. Simplifying the MCFT while maintaining acceptable generality and accuracy involved a number of considerations and assumptions. This paper gives the background to the development of these shear design equations and tables of the general method.Key words: beams, building codes, crack width and spacing, diagonal cracking, reinforced concrete, shear strength, size effect in shear, structural design.
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Keywords SURREY UNIVERSITY TRANSVERSE, WEBS, LOADS, FORMULATION, ANALYTICAL, CLAUSES, FIELD, INTERMEDIATE, STIFFENED, SHEAR, STIFFENERS, NUMERICAL, MODELS, STANDARDS, METHODS, FORCES, LINEAR, GIRDERS, LOADS, DESIGN, STUDIES, PARAMETRIC, CODES, TENSION, BEAMS, SIMPLE UK... Show All
Five 50 MPa longitudinally reinforced beams were loaded in a four-point testing setup to study their shear behavior. The beams were three meters long, and their cross section was 150 mm by 420 mm. The testing region did not contain stirrups. The beams were shallow, with a span to depth ratio of 3. All beams were similar except for the percentages of replacement of natural coarse aggregates with recycled concrete coarse aggregates, which were 0%, 10%, 20%, 35% and 100%. The results have shown that the replacement of natural coarse aggregates with recycled ones had a negligible effect on the ultimate shear strength. However, the results on the modulus of elasticity showed a reduction of less than 10% in beams with the use of recycled aggregates.
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A simple method for predicting the ultimate strength and mode of failure of reinforced concrete beams subjected to pure torsion is presented. This method is an extension of a recently developed method for predicting the strength of membrane elements subjected to pure shear that was also applied to beams subjected to combined shearing forces, bending moments, and axial loads. The torsional strength is related to the amounts of transverse and longitudinal reinforcement and to the concrete strength. To check the adequacy of this simple method, the calculated strength and mode of failure are checked against the experimental results of 66 beam tests available in the literature, and good agreement is found. The simplicity of the method is illustrated by an example.Key words: beams, building codes, mode of failure, reinforced concrete, shear, strength, torsion.
The combination of torsion with bending and shear (T-M-V) in members with both transverse and longitudinal reinforcement is the most commonly encountered combination in practical cases. Three dimensional interaction surfaces have been suggested by Hsu in 1968, Johnston in 1971, McGee in 1974 Elfren et al. in 1974. These surfaces were basically based on the interaction curves between each two stress-resultants at a time. Due to the limitations associated with experimental testing to cover all the possible factors that influence the interaction surface, theoretical models can be effectively used to establish this interaction. Currently available models such as that developed by Ewida and McMullen in 1981 have the ability to calculate the full response members subjected to the T-V-M combinations. Other more advanced models such as those developed by Rabbat and Collins in 1978 and by Rahal and Collins in 1995 are capable calculating the full response of reinforced and prestressed concrete beams subjected to any possible combination of stress-resultants.
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