•The proposed strengthening system eliminated any possible debonding up to failure.•Strengthening system is effective for increasing the shear capacity of steel girders.•Increasing the CFRP ...reinforcement ratio increases the shear strength.
This paper presents an investigation undertaken to study the effectiveness of using small-diameter CFRP strands for shear strengthening of steel bridge girders. The study includes a comprehensive experimental program to study effects of the CFRP reinforcement ratio and orientation of the strands. An analytical model, calibrated by the experimental tests, was used to provide design recommendation. Results of the study showed that the proposed strengthening system is effective in increasing the shear capacity of steel bridge girders and there was no sign of CFRP debonding or rupture failure commonly observed by CFRP laminates up to approximately 80% of the steel yield stress.
•Small-diameter CFRP strands strengthening system eliminate de-bonding failure.•CFRP strengthening achieves failure due to crushing of the concrete.•The proposed strengthening may be used to reduce ...deflection of members.•The proposed system is effective for cyclic and fatigue loadings conditions.
This paper presents the research findings of an experimental program undertaken to examine the effectiveness of using small-diameter CFRP strands to increase the flexural capacity of steel beams and bridge girders. The experimental program included scaled steel-concrete composite beams, strengthened with these small-diameter strands. The CFRP strands were stitched together with a gap between the strands to allow the adhesive to penetrate and cover the entire perimeter of each strand. Results showed that the proposed system eliminated failure due to de-bonding of the strengthening materials and significantly increased the flexural capacity and stiffness of steel beams.
This paper presents the results of a comprehensive research program, including experimental and analytical studies, to examine the use of small-diameter CFRP strands for shear strengthening of steel ...structures and bridges. The experimental program examined the effectiveness of the proposed strengthening system to increase the shear capacity of steel plates subjected to pure shear stresses using a unique test set up. A nonlinear finite element analysis (FEA), calibrated the experimental results, was used to study parameters which were not included in the experiments. Research findings indicated that the proposed system is effective for shear strengthening of steel structures and eliminated the typical debonding failure commonly observed by CFRP laminates.
•Small-diameter CFRP strands for strengthening steel structures eliminate de-bonding.•High-modulus CFRP strands provide the best system for plates under compression.•Effectiveness of the ...strengthening system increases by increasing slenderness ratio.•Increasing reinforcement ratio increases the buckling capacity of steel plate.
This paper presents the results of a study that was carried out to investigate the use of small-diameter CFRP strands for strengthening steel plates subjected to uniaxial compression. This study is part of a comprehensive research program to evaluate the use of the small-diameter CFRP strands for shear strengthening of steel girders. The research in this paper was undertaken to examine the bond characteristics of the proposed material which is expected to eliminate the debonding failure observed for CFRP laminates strengthening system and to resist the compressive stresses induced in high shear zones. The small-diameter CFRP strands are stitched together with a gap between the strands to allow each strand to be completely covered by the adhesive material. The effectiveness of the strengthening system was investigated by varying various parameters believed to affect the overall behavior including the slenderness ratio of the steel plates as well as mechanical properties and reinforcement ratios of the CFRP strands. Strengthened plates exhibited higher buckling capacity in comparison to similar plates without CFRP strands. In addition, the small-diameter CFRP strands did not show any signs of debonding at large lateral deformation associated with elastic buckling.
API650-2008 is one of the prominent codes consisting of seismic specifications to design steel storage tanks for earthquakes resistance. In spite of the code's broad application, there are some ...failure modes such as slide bottom, elephant-foot buckling, sloshing and uplift needing more evaluation. In this paper, 161 existing tanks in an oil refinery complex have been classified into 24 groups and investigated using both API650-2008 rules and numerical FEM models. Failure modes and dynamic characteristics of studied models have been calculated by numerical FEM analysis and compared with code requirements. The results demonstrate that, in some cases, there are some imperfections in the code requirements that require further investigation.
► Seismic performance of liquid storage tanks in an oil refinery complex investigated. ► Failure modes of studied steel storage tanks calculated by FEM analysis. ► Numerical FEM analysis results compared with API650-2008 code requirements. ► We report some imperfections of API650-2008 for seismic design requirements of tanks.
•Precast concrete sandwich panels can provide the shear transfer mechanism.•Quality of fabrication can affect the shear strength of the panels.•Design strength should be 30% of the sustained loads ...ultimate shear capacity.•The EPS panels are more susceptible to aging effect compared to the XPS panels.
This paper presents an experimental program to evaluate the effect of sustained loading and outdoor exposure on the shear strength of precast concrete sandwich panels connected with FRP grid/rigid foam insulation as shear transfer mechanism. CFRP and GFRP grids were considered in this study along with EPS and XPS foam. The experimental program is comprised of three different studies with a total of 26 test panels using different combinations of FRP grid and foam insulation.
There is a growing demand for strengthening steel structures and bridges due to increase of load demand and/or possible reduction of capacity caused by corrosion. Use of CFRP laminates with elastic ...modulus approximately equal to or higher than that of steel has been successfully used for flexural strengthening of steel structures; however, few researches explored the use of these materials for shear strengthening of steel structures and bridges. This thesis summarizes the findings of a comprehensive research program, including experimental and analytical studies undertaken to examine the use of small-diameter Carbon Fiber Reinforced Polymer (CFRP) strands for shear strengthening of steel structures and bridges. Most of the current research findings on the use of CFRP laminate revealed failure due to debonding since the laminates are only bonded to the substrate from one side. However, the small-diameter CFRP strands have revealed high bonding characteristics under flexural stresses. The experimental program examined the proposed strengthening system to increase the buckling capacity of steel plates subjected to uniaxial compressive stresses, relating to the principle compressive stresses arising from pure shear stress condition. A total 32 steel plates were tested under axial compressive loads to evaluate the increasing effects of plate slenderness ratio (h/t), CFRP elastic modulus, and strengthening reinforcement ratio on buckling capacity of the strengthened steel plate. The research then continued to examine the same strengthening system for increasing the shear capacity of steel plate by subjecting nine steel plates to pure shear loading conditions. The effectiveness of strengthening reinforcement ratio and orientation of CFRP strands were determined in this phase. Nonlinear finite element (FE) models, calibrated by the experimental results were used to study different parameters that were not included in the experimental program. The FE models have also used to propose design guidelines for the strengthening system. Research findings indicated that the proposed system is effective for shear strengthening of steel structures and the material used eliminated the typical debonding failure, commonly observed for strengthening systems using CFRP laminates. Based on the research finding, design guidelines are recommended for the proposed strengthening system.
The subject of progressive collapse assessment in RC structures has been concerned in various studies. In contrast, most of these studies have attended to a scenario in which an instantaneous removal ...of a column due to unexpected impact or explosion has occurred. The present study addresses progressive collapse in RC structures resulting from both instantaneous and gradual removal of columns. The scenario for a gradual removal is the result of slow decreasing strength due to fire propagation in a specific zone of structure which is partially fire-proved. A five-story building model was selected as a case study for which the nonlinear model is later developed. Vertical displacement in the upper node of the removed column, redistribution of forces after removing the column, plastic deformations in adjoining elements, and the stress imposed on the sections of the beams adjacent to the removed column in both instantaneous and gradual cases are studied.
Serbia is located at the crossroads of a historical European road, as it was a buffer zone between East and West represented by two empires, the Ottoman Empire, the Austrian Empire, and it was a ...battlefield in favor of the great powers. The Austrians in particular, and that their control over it took place after several attempts in the year 1450 AD. It became clear through research that Serbia is an agricultural country primarily dependent on agriculture and animal husbandry, and the Ottomans imposed taxes on them. As for education in Serbia, it was primitive and within the church only, and that the law used It is the law of Dushan and the teachings of the church in addition to some Ottoman laws. The national spirit grew to obtain independence among the Serbs after they were exhausted by taxes, the treatment of the Janissaries, and their domination, in addition to many of the reasons that prompted them to revolt and demand independence, which eventually led to the Serbian revolution in 1804 AD
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