Flexural stiffness of steel-concrete composite beam under positive moment

et al. 2021

Applied Sciences

Vertical deflection of a frame beam is an important indicator in the limit-state analysis of frame structures, particularly for steel–concrete composite beams, which are usually designed with large spans and heavy loads. In this study, the equivalent flexural stiffness of composite frame beams is analysed to evaluate their vertical deflection. A theoretical beam model with a spring constraint boundary and varied stiffness segments is established to consider the influence of both the rotation restraint stiffness at the beam ends and the cracked section in the negative moment region, such that the inelastic bending deformation of the composite beams can be elaborately described. By an extensive parametric analysis, a fitting formula for evaluating the equivalent flexural stiffness of the composite beams, including the effects of the rotational constraint and the concrete cracking, is obtained. The validity of the proposed formula is demonstrated by comparing its calculation accuracy with those of existing design formulas for analysing the equivalent flexural stiffness of the composite beam members. Moreover, its utility is further verified by conducting non-linear finite element simulations of structural systems to examine the serviceability limit state and the entire process evolution of beam deflections under vertical loading. Finally, to facilitate the practical application of the proposed formula in engineering design, a simplified method to calculate the deflection of composite beams, which utilises the internal force distribution of elastic analysis, is presented based on the concept of equivalent flexural stiffness.

Section: Introductionmentioning

confidence: 75%

Analysis of Equivalent Flexural Stiffness of Steel–Concrete Composite Beams in Frame Structures

Tao

et al. 2021

Applied Sciences

“…Detailed strengths were determined based on measured data in Table 2, and the parameter settings of the steel and concrete constitutive models can be found in reference [17]. e effectiveness of those constitutive models has been validated through a series of experimental studies [18,19]. A trilinear model was applied to the shear stud material.…”

Section: Materials Propertiesmentioning

confidence: 99%

Static Behavior of a Modified Through‐Core Connection between CFST Column and Composite Beam

Advances in Civil Engineering

et al. 2019

Through-core connection has been proven to be an ideal solution to ensure a rigid connection between steel beams and CFST columns. However, the traditional through-core connection sometimes encounters concrete filling problems. A modified through-core connection design with details of reduced flange width was therefore proposed. Through-core reinforcements were added as supplements for tension load transfer. The monotonic loading tests and comprehensive FE simulations were performed to investigate the load bearing performance and working mechanism of this modified connection. The results indicated that the modified through-core connection presented plasticity hinge failure at the beam end and crack formulation and progradation at the RC slab. The reduced flange width reduced the strength of the connection, but the reduction extent was limited. Due to the through-core construction, the majority of internal forces at the beam were directly transferred into the column. The through-core reinforcement can effectively participate in load bearing after the connection yields. The flange width reduction extent and the length of the reduction region must be controlled to ensure sufficient connection strength. The number of shear studs and TC reinforcements can influence the load bearing ability, and design suggestions are provided for the modified through-core connection.

“…Moreover, although a beam is designed as a full composite section, a perfect composite action without any slip could not be obtained due to the deformation of shear studs. The effect of slip on the deflection of a SCCBB with partial shear connections may be significant, and the deflection calculated by ignoring this interface slip would underestimate the deflection compared to the experimental measurements (Ding et al, 2016;Liu et al, 2016;Nie et al, 2004Nie et al, , 2007Safa et al, 2016). At the same time, the negligence of the shear deformation of the concrete slab and steel box beam such as Euler-Bernoulli beams (i.e.…”

Section: Introductionmentioning

confidence: 98%

Natural vibration analysis of steel–concrete composite box beam using improved finite beam element method

Jiang

Lai

Advances in Structural Engineering

et al. 2017

Based on Hamilton's principle and a cubic Hermite polynomial shape function, first the improved steel-concrete composite box beam element stiffness and mass matrixes with a few numbers of degree were derived by considering many influencing factors such as interface slip, shear lag, shear deformation, and rotational inertia, and then the finite beam element method program was established. The natural vibration frequencies of many steel-concrete composite box beam calculation samples with different spans, degrees of shear connection, and boundary conditions were calculated. The analysis results show that the finite beam element method calculation results are consistent with ANSYS' calculation, thus demonstrating the rationality and validity of the improved steel-concrete composite box beam element stiffness and mass matrixes proposed in this study. Moreover, some meaningful conclusions to engineering design were drawn as follows: The effect of shear lag increases with the order of steel-concrete composite box beam's natural vibration frequency and degree of shear connection. Shear deformation also increases with the order of steel-concrete composite box beam's natural vibration frequency; thus, the shear deformation corresponding to the steel-concrete composite box beam's highorder natural vibration frequency cannot be ignored. The interface slip of steel-concrete composite box beam's high-order natural vibration frequency is negligible; however, the interface slip of steel-concrete composite box beam's low-order natural vibration frequency cannot be ignored.