• Title, Summary, Keyword: steel beams

Search Result 1,603, Processing Time 0.052 seconds

Analysis of restrained heated steel beams during cooling phase

  • Li, Guo-Qiang;Guo, Shi-Xiong
    • Steel and Composite Structures
    • /
    • v.9 no.3
    • /
    • pp.191-208
    • /
    • 2009
  • Observations from experiments and real fire indicate that restrained steel beams have better fire-resistant capability than isolated beams. Due to the effects of restraints, a steel beam in fire condition can undergo very large deflections and the run away damage may be avoided. However disgusting damages may occur in the beam-to-column connections, which is considered to be mainly caused by the enormous axial tensile forces in steel beams resulted from temperature decreasing after fire dies out. Over the past ten years, the behaviour of restrained steel beams subjected to fire during heating has been experimentally and theoretically investigated in detail, and some simplified analytical approaches have been proposed. While the performance of restrained steel beams during cooling has not been so deeply studied. For the safety evaluation and repair of steel structures against fire, more detailed investigation on the behaviour of restrained steel beams subjected to fire during cooling is necessary. When the temperature decreases, the elastic modulus and yield strength of steel recover, and the contraction force in restrained steel beams will be produced. In this paper, an incremental method is proposed for analyzing the behaviour of restrained steel beams subjected to cooling. In each temperature decrement, the development of deformation and internal forces of a restrained beam is divided into four steps, in order to consider the effect of the recovery of the elastic modulus and strength of steel and the contraction force generated by temperature decrease in the beam respectively. At last, the proposed approach is validated by FE method.

A Numerical Investigation on Restrained High Strength Q460 Steel Beams Including Creep Effect

  • Wang, Weiyong;Zhang, Linbo;He, Pingzhao
    • International journal of steel structures
    • /
    • v.18 no.5
    • /
    • pp.1497-1507
    • /
    • 2018
  • Most of previous studies on fire resistance of restrained steel beams neglected creep effect due to lack of suitable creep model. This paper presents a finite element model (FEM) for accessing the fire resistance of restrained high strength Q460 steel beams by taking high temperature Norton creep model of steel into consideration. The validation of the established model is verified by comparing the axial force and deflection of restrained beams obtained by finite element analysis with test results. In order to explore the creep effect on fire response of restrained Q460 steel beams, the thermal axial force and deflection of the beams are also analyzed excluding creep effect. Results from comparison infer that creep plays a crucial role in fire response of restrained steel beam and neglecting the effect of creep may lead to unsafe design. A set of parametric studies are accomplished by using the calibrated FEM to evaluate the governed factors influencing fire response of restrained Q460 steel beams. The parametric studies indicate that load level, rotational restraint stiffness, span-depth ratio, heating rate and temperature distribution pattern are key factors in determining fire resistance of restrained Q460 steel beam. A simplified design approach to determine the moment capacity of restrained Q460 steel beams is proposed based on the parametric studies by considering creep effect.

Experiment research on seismic performance of prestressed steel reinforced high performance concrete beams

  • Xue, Weichen;Yang, Feng;Li, Liang
    • Steel and Composite Structures
    • /
    • v.9 no.2
    • /
    • pp.159-172
    • /
    • 2009
  • Two prestressed steel reinforced high performance concrete (SRC) beams, a nonprestressed SRC beam and a counterpart prestressed concrete beam were tested under low reversed cyclic loading to evaluate seismic performance of prestressed SRC beams. The failure modes, deformation restoring capacity, ductility and energy dissipation capacity of the prestressed SRC beams were discussed. Results showed that due to the effect of plastic deformations of steel beams encased in concrete, the three SRC beams exhibited residual deformation ratios ranging between 0.64 and 0.79, which were apparently higher than that of the prestressed concrete beam (0.33). The ductility coefficients of the prestressed SRC beams and the prestressed concrete beam ranged between 4.65 and 4.87, obviously lower than that of nonprestressed SRC beam (9.09), which indicated the steel beams influenced the ductility little while prestressing resulted in an apparent reduction in ductility. The amount of energy dissipated by the prestressed SRC beams was less than that dissipated by the nonprestressed SRC beam but much more than that dissipated by the prestressed concrete beam.

Effect of stiffeners on failure analyses of optimally designed perforated steel beams

  • Erdal, Ferhat
    • Steel and Composite Structures
    • /
    • v.22 no.1
    • /
    • pp.183-201
    • /
    • 2016
  • Perforated steel beams can be optimised by increased beam depth and the moment of inertia combined with a reduced web thickness, favouring the use of original I-section beams. The designers are often confronted with situations where optimisation cannot be carried out effectively, taking account of the buckling risk at web posts, moment-shear transfers and local plastic deformations on the transverse holes of the openings. The purpose of this study is to suggest solutions for reducing these failure risks of tested optimal designed beams under applying loads in a self-reacting frame. The design method for the beams is the hunting search optimisation technique, and the design constraints are implemented from BS 5950 provisions. Therefore, I have aimed to explore the strengthening effects of reinforced openings with ring stiffeners, welded vertical simple plates on the web posts and horizontal plates around the openings on the ultimate load carrying capacities of optimally designed perforated steel beams. Test results have shown that compared to lateral stiffeners, ring and vertical stiffeners significantly increase the loadcarrying capacity of perforated steel beams.

Economic Analysis of Economic Steel beam method. (ES 빔 공법의 경제성 분석)

  • Choi, Tae-Ho;Woo, Jong-Yeol;Hong, Seong-Wook;Seo, Yong-Chil;Shin, Chan-Ho
    • Proceedings of the Korean Institute of Building Construction Conference
    • /
    • /
    • pp.133-136
    • /
    • 2011
  • This study concerned with the steel beam of bonding method and bonded steel beams by this method and both ends of different height, steel beams and steel beams in the center makes the junction. Both ends and the central part of steel beams connecting the lower flange by additional combining steel plates to convey stress, the stress to focus on the beam connections are passed to both ends of steel beams, and strength of beam connections is improved and steel structural beams is proposed to minimize the loss by Incision. If you use the developed method, the construction period is shortened, and reducing the amount of material can decrease the cost and reduction in floor height can be maximized business feasibility.

  • PDF

A simplified approach for fire-resistance design of steel-concrete composite beams

  • Li, Guo-Qiang;Wang, Wei-Yong
    • Steel and Composite Structures
    • /
    • v.14 no.3
    • /
    • pp.295-312
    • /
    • 2013
  • In this paper, a simplified approach based on critical temperature for fire resistance design of steel-concrete composite beams is proposed. The method for determining the critical temperature and fire protection of the composite beams is developed on the basis of load-bearing limit state method employed in current Chinese Technical Code for Fire safety of Steel Structure in Buildings. Parameters affecting the critical temperature of the composite beams are analysed. The results show that at a definite load level, section shape of steel beams, material properties, effective width of concrete slab and concrete property model have little influence on the critical temperature of composite beams. However, the fire duration and depth of concrete slab have significant influence on the critical temperature. The critical temperatures for commonly used composite beams, at various depth of concrete and fire duration, are given to provide a reference for engineers. The validity of the practical approach for predicting the critical temperature of the composite beams is conducted by comparing the prediction of a composite beam with the results from some fire design codes and full scale fire resistance tests on the composite beam.

Stress and Deflection Analysis of Steel Beams at Elevated Temperature (온도상승에 따른 Steel-beam의 응력 및 처짐 해석)

  • Jang, Myung-Woong;Kang, Moon-Myung;Kang, Sung-Duk
    • Journal of Korean Association for Spatial Structures
    • /
    • v.3 no.1
    • /
    • pp.57-68
    • /
    • 2003
  • This paper have performed to investigate the influence of certain parameters, including the boundary condition types, load ratios of the steel beams, and span/depth ratios of the beams itself on the structural behaviour of the steel beams at elevated temperatures. This paper is analysed the stress and vertical deflection at mid-span of the steel beams at elevated temperatures and also predicted 'failure' temperatures of the steel beams at elevated temperatures. Fire analysis used here is analysed by software VULCAN. Design examples are given to describe the structural behaviour of the steel beams at elevated temperatures.

  • PDF

Experimental studies on composite beams with high-strength steel and concrete

  • Zhao, Huiling;Yuan, Yong
    • Steel and Composite Structures
    • /
    • v.10 no.5
    • /
    • pp.373-383
    • /
    • 2010
  • This paper presents the experimental studies of the flexural behavior of steel-concrete composite beams. Herein, steel-concrete composite beams were constructed with a welded steel I section beam and concrete slab with different material strength. Four simply supported composite beams subjected to two-point concentrated loads were tested and compared to investigate the effect of high strength engineering materials on the overall flexural response, including failure modes, load deflection behavior, strain response and interface slip. The experimental results show that the moment capacity of composite beams has been improved effectively when high-strength steel and concrete are used. Comparisons of the ultimate flexural strength of beams tested are then made with the calculated results according to the methods specified in guideline Eurocode 4. The ultimate flexural strength based on current codes may be slightly unconservative for predicating the moment capacity of composite beams with high-strength steel or concrete.

Experimental investigation of low-velocity impact characteristics of steel-concrete-steel sandwich beams

  • Sohel, K.M.A.;Richard Liew, J.Y.;Alwis, W.A.M.;Paramasivam, P.
    • Steel and Composite Structures
    • /
    • v.3 no.4
    • /
    • pp.289-306
    • /
    • 2003
  • A series of tests was conducted to study the behaviour of steel-composite sandwich beams under low velocity hard impact. Damage characteristic and performance of sandwich beams with different spacing of shear connector were evaluated under impact loading. Thin steel plates were used as top and bottom skins of the sandwich beams and plain concrete was used as the core material. Shear connectors were provided by welding of angle sections on steel plates. The sandwich beams were impacted at their midpoint by a hemi-spherical nose shaped projectile dropped from various heights. Strains on steel plates were measured to study the effects of impact velocity or impact momentum on the performance of sandwich beams. Spacing of shear connectors is found to have significant effects on the impact response of the beams.

Shear lag effect in steel-concrete composite beam in hogging moment

  • Luo, Da;Zhang, Zhongwen;Li, Bing
    • Steel and Composite Structures
    • /
    • v.31 no.1
    • /
    • pp.27-41
    • /
    • 2019
  • Shear lag effect can be an important phenomenon to consider in design of the steel-concrete composite beams. Researchers have found that the effect can be strongly related with the moment distribution, the stiffness and the ductility of the composite beams. For continuous composite beams expected to sustain hogging moment, the shear lag effect can be more distinct as cracking of the concrete slab reduces its shear stiffness. Despite its influences on behaviour of the steel-concrete composite beams, a method for calculating the shear lag effect in steel-concrete composite beams sustaining hogging moment is still not available. Shear lag effect in steel-concrete composite beams sustaining hogging moment is investigated in this paper. A method was proposed specifically for predicting the effect in the cracked part of the steel-concrete composite beam. The method is validated against available experimental data. At last, FE studies are conducted for steel-concrete composite beams with different design parameters, loading conditions and boundary conditions to further investigate the shear lag effect and compare with the proposed method.