Numerical analysis of torsional tangent rigidity of reinforced concrete waffle slab

This research work deals with the analysis of torsional tangent rigidity of reinforced concrete waffle slabs by comparisons of the numerical analysis with results of experimental tests, with calculations performed using the ATENA program. This program was specially developed for the calculation of reinforced concrete structures, considering the physical and geometric nonlinear analysis using the finite element method. Numerical analysis considered the tensile strength of the concrete and consequently the fracture energy. Numerical situations were tested to obtain the calibration of the numerical analysis with the laboratory tests. After the calibrations, the results were extrapolated to extreme situations to infer tangent torsion rigidity in new situations. It is concluded that, for waffle slabs, near the rupture, the torsional tangent rigidity should be 5% of the torsional tangent rigidity to the initial torsion. In service, considering one third of the total breaking load, the torsional tangent rigidity should be 85% of the torsional tangent rigidity to the initial twist. This great torsional tangent rigidity in service is another parameter that guarantees the structural efficiency of the waffle slabs and can be used in the most diverse applications of structural engineering.

Study on Diseases of Multi-Box Girder Bridge

Because the multi-box girder bridge has many advantages, such as large torsion rigidity, large load-bearing capacity, stability, fine appearance, good applicability and convenient construction, it is widely used in China. But for the defection existing in design and construction, many box girders have serious diseases. Aiming at the diseases of a viaduct bridge, the causes of diseases are analyzed and the enforcement method is proposed in this paper. The study shows that, though the box girders have large torsion rigidity, the diaphragms are designed necessarily to enhance the transversal connection between the box girders, to make them bear the loads together, to reduce their stresses and deformation, and to reduce the stresses of deck too.

Pseudo-Plate Method of High-Strength Steel Fiber Concrete Multi-Ribbed Slab

Basing on the disadvantages of multi-ribbed slab in practice, a new high-strength steel fiber concrete (HSFC) composite multi-ribbed slab structure is introduced. Because adding steel fibers can improve the capacity of the concrete, it also can make some influence on the mechanic performance of HSFC multi-ribbed slab, such as elastic module, shear module, flexural rigidity, and torsion rigidity and so on. So by the analysis of the material and mechanic capacity and considering the influence of steel fiber, the formulas to calculate flexural rigidity, torsion rigidity, deflection and internal force of the new composite slab are given, in which the multi-ribbed slab is equivalent to orthotropic slab by the principle of stiffness coincidence. The study in this paper can provide some valuable theory references for further study and application of multi-ribbed slab.

A New Conception of Free Torsion Rigidity in Constraint Torsion Theory for Members with Open Thin-Walled Cross-Section

In calculating the internal force and deformation of a thin-walled member, the influence of the free torsion rigidity must be considered and it makes the study complicated. Actually, from the analogy relations between the equilibrium equation in the constraint torsion theory of a thin-walled member and that in the plane bending theory of a tension-bending solid bar, the action of the free torsion rigidity can be regarded as a tension effect on a thin-walled member with torsion, i.e. the action can be described as a second-order effect like the tension action in the plane bending theory. Taking cantilever bars for example, the simple calculation method of the internal force and deformation of thin-walled members are deduced by the Taylor series in mathematics, and then verified by ANSYS.

A New FEM for Torsion Cracked Cylinder Based on Crack3D FEA Code and Mushhelisvili Torsion Theorem

The objective of this paper is to use the specialty fracture software Crack3D FEA Code, well known Ansys software and Mushhelisvili’s torsion theorem to analyze the torsion problem of a crack rectangular cylinder. Several numerical results such as stress intensity factors KIII , torsion rigidity D, shearing stresses (τxy ,τyz ) and the contour nodal solution data are obtained. All the results are satisfactory.