• Journal of Korean Society of Steel Construction
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• v.22 no.4
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• pp.377-388
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• 2010

The flexural behavior of composite HSB600 and HSB800 I-girders under a positive moment was investigated using the material non-linear moment-curvature analysis method. Three representative composite sections with different ductility properties were selected as the baseline sections in this study. Using these baseline sections, the moment-curvature program was verified by comparing the flexural strength and the moment-curvature curve obtained from the program with those obtained using the non-linear FE analysis of ABAQUS. In the FE analysis, the composite girders were modeled three-dimensionally with flanges, the web, and the concrete slab as thin shell elements, and initial imperfections and residual stresses were imposed on the FE model. In the moment-curvature and FE analyses, the 28-day compressive strength of the concrete slab was assumed to be 30-50 MPa, and the HSB600 and HSB800 steels were modeled as elasto-plastic strain-hardening materials, with the concrete as the CEB-FIP model. The effects of the ductility ratio of the composite girder, the type of steel, the compressive strength of the concrete deck, and the location of the plastic neutral axis on the flexural characteristics were analyzed.

• Steel and Composite Structures
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• v.49 no.4
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• pp.381-392
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• 2023

This study experimentally investigates the flexural behavior of steel-UHPC composite slabs composed of an innovative negative Poisson's ratio (NPR) steel plate and Ultra High Performance Concrete (UHPC) slab connected via demountable high-strength bolt shear connectors. Eight demountable composite slab specimens were fabricated and tested under traditional four-point bending method. The effects of loading histories (positive and negative bending moment), types of steel plate (NPR steel plate and Q355 steel plate) and spacings of high-strength bolts (150 mm, 200 mm and 250 mm) on the flexural behavior of demountable composite slab, including failure mode, load-deflection curve, interface relative slip, crack width and sectional strain distribution, were evaluated. The results revealed that under positive bending moment, the failure mode of composite slabs employing NPR steel plate was distinct from that with Q355 steel plate, which exhibited that part of high-strength bolts was cut off, part of pre-embedded padded extension nuts was pulled out, and UHPC collapsed due to instantaneous instability and etc. Besides, under the same spacing of high-strength bolts, NPR steel plate availably delayed and restrained the relative slip between steel plate and UHPC plate, thus significantly enhanced the cooperative deformation capacity, flexural stiffness and load capacity for composite slabs further. While under negative bending moment, NPR steel plate effectively improved the flexural capacity and deformation characteristics of composite slabs, but it has no obvious effect on the initial flexural stiffness of composite slabs. Meanwhile, the excellent crack-width control ability for UHPC endowed composite members with better durability. Furthermore, according to the sectional strain distribution analysis, due to the negative Poisson's ratio effect and high yield strength of NPR steel plate, the tensile strain between NPR steel plate and UHPC layer held strain compatibility during the whole loading process, and the magnitude of upward movement for sectional plastic neutral axis could be ignored with the increase of positive bending moment.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.369-372
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• 2006

In this paper, analysis method of HPFRCC is proposed as predicting properties flexural behavior. For analyzing HPFRCC beam, properties of strain-hardening, multiple cracking, and crack spacing control are considered as non-homogeneous material properties of the beam. This paper focused on the deflection, maximum moment of the flexural beam, distribution of crack width with the monte carlo simulation.

• International Journal of Safety
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• v.11 no.2
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• pp.26-28
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• 2012

In this thesis, fracture tests were carried out in order to investigate the flexural strength behavior of FRC(fiber reinforced concrete) structures. FRC beams were used in the tests, the initial crack load and the ultimate load of the beams were observed under the static loading. According to the results, the ultimate loads increase with the fiber content, and these tendency is clear in the specimens with large fiber aspect ratio. From the results of the regression analysis, practical formulae for predicting the flexural strength of FRC were suggested.

• Structural Engineering and Mechanics
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• v.77 no.1
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• pp.89-102
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• 2021

Rapid construction of prefabricated bridges requires minimizing the field work of precast members and ensuring structural stability and constructability. In this study, we conducted experimental and analytical investigations of transverse joints of prefabricated T-girder bridge superstructures to verify the flexural performance and serviceability. In addition, we conducted parametric studies to identify the joint parameters. The results showed that both the segmented and continuous specimens satisfied the ultimate flexural strength criterion, and the segmented specimen exhibited unified behavior, with the flexural strength corresponding to that of the continuous specimen. The segmented specimens exhibited elastic behavior under service load conditions, and the maximum crack width satisfied the acceptance criteria. The reliability of the finite element model of the joint was verified, and parametric analysis of the convexity of the joint section and the compressive strength of the filler concrete showed that the minimum deflection and crack width occurred at a specific angle. As the strength of the filler concrete increased, the deflection and crack width decreased. However, we confirmed that the reduction in the crack width was hardly observed above a specific strength. Therefore, a design suitable for prefabricated bridges and accelerated construction can be achieved by improving the joint specifications based on the required criteria.

• Steel and Composite Structures
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• v.3 no.2
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• pp.123-140
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• 2003

The importance of the research on moment-resistant properties of unstiffened tubular joints and the research background are introduced. The performed experimental research on the bending rigidity and capacity of the joints is reported. The emphasis is put on the discussion of the flexural behavior of the joints including sets of geometrical parameters of the joints and several loading combinations. Procedures and results of loading tests on four full size joints in planar KK and X configuration are described in details at first. Mechanical models are proposed to analyze the joint specimens. Three-dimensional nonlinear FE models are established and verified with the experimental results. By comparing the experimental data with the results of the analysis, it is reported reasonable to carry out the structural analysis under the assumption that the joint is fully rigidly connected, and their bending capacities can assure the strength of the members connected under certain limitation. Furthermore, a parametric formula for inplane bengding rigidity of T and Y type tubular joints is proposed on the basis of FE calculation and regression analysis. Compared with test results, it is shown that the parametric formula developed in this paper has good applicability.

• Advances in concrete construction
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• v.11 no.3
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• pp.239-253
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• 2021

The behavior of concrete containing waste glass as a replacement of cement or aggregate was studied previously in the most of researches, but the present investigation focuses on the recycling of waste glass powder as a substitute for silica fume in high strength concrete (HSC). This endeavor deals with the efficiency of using waste glass powder, as an alternative for silica fume, in the flexural capacity of HSC beam. Thirteen members with dimensions of 0.3 m width, 0.15 m depth and 0.9 m span length were utilized in this work. A comparison study was performed considering HSC members and hybrid beams fabricated by HSC and conventional normal concrete (CC). In addition to the experiments on the influence of glass powder on flexural behavior, numerical analysis was implemented using nonlinear finite element approach to simulate the structural performance of the beams. Same constitutive relationships were selected to model the behavior of HSC with waste glass powder or silica fume to show the matching between the modeling outputs for beams made with these powders. The results showed that the loading capacity and ductility index of the HSC beams with waste glass powder demonstrated enhancing ultimate load and ductility compared with those of HSC specimens with silica fume. The study deduced that the recycled waste glass powder is a good alternative to the pozzolanic powder of silica fume.

• Steel and Composite Structures
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• v.30 no.2
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• pp.149-169
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• 2019

A new form of composite column, concrete-filled round-ended steel tubes (CFRTs), has been proposed as piers or columns in bridges and high-rise building and has great potential to be used in civil engineering. Hence, the objective of this paper presents an experimental and numerical investigation on the flexural behavior of CFRTs through combined experimental results and ABAQUS standard solver. The failure mode was discussed in detail and the specimens all behaved in a very ductile manner. The effect of different parameters, including the steel ratio and aspect ratio, on the flexural behavior of CFRTs was further investigated. Furthermore, the feasibility and accuracy of the numerical method was verified by comparing the FE and experimental results. The moment vs. curvature curves of CFRTs during the loading process were analyzed in detail. The development of the stress and strain distributions in the core concrete and steel tube was investigated based on FE models. The composite action between the core concrete and steel tube was discussed and clarified. In addition, the load transfer mechanism of CFRT under bending was introduced comprehensively. Finally, the predicted ultimate moment according to corresponding designed formula is in good agreement with the experimental results.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.207-216
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• 2007

The flexural behavior of steel composite beam with built-up cross-section by bolt connection is presented in this paper. The composite effect due to bolt-connetion and friction between steel plate are considered to investigate the flexural behavior of steel composite beam. The displacement, bending stresses and shear stresses according to composite rate are calculated by F.E. analysis and these results are compared to the analytical values of non interaction beam and full interaction beam. As a result of analysis, the behavior of composite beam is more dependant on the composite rate than the friction of the steel plate. When the composite rate reaches $50{\sim}60%$, the behavior of composite beam is similar to that of fully composite beam.

• Steel and Composite Structures
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• v.37 no.3
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• pp.353-369
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• 2020

Eight cold-formed thin-walled steel beams were performed to investigate the effect of corrosion damage on the flexural behavior of steel beams. The relationships between failure modes or load-displacement curves and corrosion degree of steel beams were investigated. A series of parametric analysis with more than forty finite element models were also performed with different corrosion degrees, types and locations. The results showed that the reduction of cross-section thickness as well as corrosion pits on the surface would lead to a decline in the stiffness and flexural capacity of steel beams, and gradually intensified with the corrosion degree. The yield load, ultimate load and critical buckling load of the corroded specimen IV-B46-4 decreased by 22.2%, 26% and 45%, respectively. The failure modes of steel beams changed from strength failure to stability failure or brittle fracture with the corrosion degree increasing. In addition, thickness damage and corrosion pits at different locations caused the degradation of flexural capacity, the worst of which was the thickness damage of compression zone. Finally, the method for calculating flexural capacity of corroded cold-formed thin-walled steel beams was also proposed based on experimental investigation and numerical analysis results.