Abstract
In this paper, the distortion of simply supported girders with inner diaphragms subjected to concentrated eccentric loads is investigated using initial parameter method (IPM), in which the in-plane shear deformation of diaphragms is fully considered. A statically indeterminate structure was modeled with inner redundant forces, where the interactions between the girder and diaphragms were indicated by a distortional moment. Considering the compatibility condition between the girder and diaphragms, solutions for the distortional angle, warping displacements and stresses were derived and further simplified by establishing a matrix equation system. The validity of IPM was intensively verified by a finite element analysis and distortional experiments. Parametric studies were then performed to examine the effect of the diaphragm number on the distortional angle, warping displacements and stresses under various ratios of height to span of the girder and the diaphragm thicknesses. Besides, stabilities of the local web plate and mid-span diaphragm were analyzed based on IPM for box girders with symmetrical three inner diaphragms. Results show that the local web plate will buckle before overall yielding with the increment of the eccentric loads Pj, and the mid-span diaphragm is constantly stable in the whole deformation process. It shows that more attentions should be paid on the stability of the local web plate than overall yielding for girders subjected to eccentric loads.
Highlights
During the past several decades, box girders have been widely applied in buildings and bridges due to their large bending and torsional stiffness
The initial parameter method (IPM) is applied to investigate the distortion of supported girders with inner diaphragms subjected to concentrated eccentric loads, where inplane shear deformation of diaphragms is considered
(1) Compared with results from FEA and experiments, accurate analyses can be obtained by Initial parameter method (IPM) for the distortional angle, warping displacements and stresses for supported girders with inner diaphragms
Summary
During the past several decades, box girders have been widely applied in buildings and bridges due to their large bending and torsional stiffness. They are generally susceptible to the cross-sectional distortion [1] under eccentric loads due to their quadrilateral instability. ⇑ Corresponding author at: Key Lab of Civil Engineering Safety and Durability of. China Education Ministry, Department of Civil Engineering, Tsinghua University, Beijing 100084, China. Li [6,7] proposed that the shear strain of the cross section cannot be ignored when the distortional shear rigidity is significant compared to the distortional warping one for box girders. Based on BEF, Hsu [9,10] proposed the Equivalent Beam on Elastic Foundation (EBEF) analogy considering the shear strain of the cross section, and found that the EBEF analogy is more versatile than BEF due to its simplicity in analyzing more complex problems such as non-uniform sections and multispan beams
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