• Advances in concrete construction
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• v.13 no.2
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• pp.183-190
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• 2022

A wide range of experimental bases and improved performance with different forms of Fiber Reinforced Polymer (FRP) have attracted researchers to produce eco-friendly and sustainable structures. The reinforced concrete (RC) beam's shear capacity has remained a complex phenomenon because of various parameters affecting. Design recommendations for the shear capacity of RC elements having FRP reinforcement need a more experimental database to improve design recommendations because almost all the recommendations replace different parameters with FRP's. Steel and FRP are fundamentally different materials. One is ductile and isotropic, whereas the other is brittle and orthotropic. This paper presents experimental results of the investigation on the beams with glass fiber reinforced polymer (GFRP) reinforcement as longitudinal bars and stirrups. Total twelve beams with GFRP reinforcement were prepared and tested. The cross-section of the beams was rectangular of size 230 × 300 mm, and the total length was 2000 mm with a span of 1800 mm. The beams are designed for simply-supported conditions with the two-point load as per specified load positions for different beams. Flexural reinforcement provided is for the balanced conditions as the beams were supposed to test for shear. Two main variables, such as shear span and spacing of stirrups, were incorporated. The beams were designed as per American Concrete Institute (ACI) ACI 440.1R-15. Relation of VExp./VPred. is derived with axial stiffness, span to depth ratio, and stirrups spacing, from which it is observed that current design provisions provide overestimation, particularly at lower stirrups spacing.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.93-101
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• 2024

Code-compliant seismic design should be essentially applied to realize the so-called emulative performance of precast concrete (PC) lateral force-resisting systems, and this study developed simple procedures to design precast industrial buildings with intermediate precast bearing wall systems considering both the effect of seismic and blast loads. Seismic design provisions specified in ACI 318 and ASCE 7 can be directly adopted, for which the so-called 1.5S_y condition is addressed in PC wall-to-wall and wall-to-base connections. Various coupling options were considered and addressed in the seismic design of wall-to-wall connections for the longitudinal and transverse design directions to secure optimized performance and better economic feasibility. On the other hand, two possible methods were adopted in blast analysis: 1) Equivalent static analysis (ESA) based on the simplified graphic method and 2) Incremental dynamic time-history analysis (IDTHA). The ESA is physically austere to use in practice for a typical industrial PC-bearing wall system. Still, it showed an overestimating trend in terms of the lateral deformation. The coupling action between precast wall segments appears to be inevitably required due to substantially large blast loads compared to seismic loads with increasing blast risk levels. Even with the coupled-precast shear walls, the design outcome obtained from the ESA method might not be entirely satisfactory to the drift criteria presented by the ASCE Blast Design Manual. This drawback can be overcome by addressing the IDTHA method, where all the design criteria were fully satisfied with precast shear walls' non-coupling and group-coupling strength, where each individual or grouped shear fence was designed to possess 1.5S_y for the seismic design.

• Journal of the Korea Concrete Institute
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• v.26 no.2
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• pp.189-199
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• 2014

Currently, in the precast concrete construction, Precast Concrete (PC) and Cast-In-Place (CIP) concrete with different concrete strengths are frequently used. However, current design codes do not specifically provide shear design methods for PC-CIP hybrid members using dual concrete strengths. In the present study, simply supported composite beams with shear reinforcement were tested. The test variables were the area ratio of the two concretes, spacing of shear reinforcement, and shear span-to-depth ratio. The shear strengths of the test specimens were evaluated by current design codes on the basis of the test results. The results showed that the shear strength of the composite beams was affected by the concrete strength of the compressive zone and also proportional to the flexural rigidity of un-cracked sections. Furthermore, the contribution of shear reinforcements varied according to the concrete strength of the compressive zone.

• Journal of the Earthquake Engineering Society of Korea
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• v.28 no.2
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• pp.77-83
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• 2024

The design shear strength equations of RC shear walls have been developed based on their performance under in-plane (IP) loads, thereby failing to account for the potential performance degradation of shear strength when subjected to simultaneous out-of-plane (OOP) loading. Most of the previous experimental studies on RC walls have been conducted in one direction under quasi-static conditions, and due to the difficulty in experimental planning, there is a lack of research on cyclic loading and results under multi-axial loading conditions. During an earthquake, shear walls may yield earlier than their design strength or fail unexpectedly when subjected to multi-directional forces, deviating from their intended failure mode. In this paper, nonlinear analysis in finite element models was performed based on the results of cyclic loading experiments on reinforced concrete shear walls of auxiliary buildings. To investigate the reduction trend in IP shear capacity concerning the OOP load ratio, parametric analysis was conducted using the shear wall FEM. The analysis results showed that as the magnitude of the OOP load increased, the IP strength decreased, with a more significant effect observed as the size of the opening increased. Thus, the necessity to incorporate this strength reduction as a factor for the OOP load effect in the wall design strength equation should be discussed by performing various parametric studies.

• Geomechanics and Engineering
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• v.9 no.5
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• pp.601-618
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• 2015

Soil-reinforcement interaction mechanism is an important issue in the design of geosynthetic reinforced soil structures. This mechanism depends on the soil properties, reinforcement characteristics and interaction between these two elements (soil and reinforcement). In this work the shear strength of sand/geotextile interfaces were characterized through direct and simple shear tests. The direct shear tests were performed on a conventional direct shear device and on a large scale direct shear apparatus. Unreinforced sand and one layer reinforced sand specimens were characterized trough simple shear tests. The interfaces shear strength achieved with the large scale direct shear device were slightly larger than those obtained with the conventional direct shear apparatus. Notwithstanding the differences between the shear strength characterization through simple shear and direct shear tests, it was concluded that the shear strength of one layer reinforced sand is similar to the sand/geotextile interface direct shear strength.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.45-51
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• 1992

Trilinear analytical models representing the behavior of composite beam-steel column joints and seismic shear design method for the joints are presented. Emphasis is placed on the effect of the concrete slab on the behavior of the joints. To validate the analytical models, Comparisons with the experimental results are made. Application of the proposed method to seismic shear design of joints improves the seismic resistance of the steel frame with composite slab.

• Steel and Composite Structures
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• v.27 no.4
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• pp.401-416
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• 2018

Composite beams with web openings are vulnerable to Vierendeel bending failure. The available methods provide quite conservative estimates of Vierendeel bending resistance. An alternative design method to compute the resistance was proposed in this study, based on quadratic nonlinear interactions of normalized shear force, axial force and Vierendeel bending moment. The interactions of the top and bottom Tee section must satisfy mutual conditions to prevent the Vierendeel failure. The normalized shear force and Vierendeel bending moment of the composite part were used instead in the top Tee interaction. The top Tee axial force was computed based on force equilibrium. Based on a rigid-plastic model, the composite resistance is estimated using an effective slab width of the vertical shear resistance. On using the proposed method, nonlinear reductions due to shear loads and axial forces are not required, in contrast to prior methods. The proposed method was validated against experiments from literature. The method limitations and accuracy as well as the Vierendeel behavior were investigated by finite element simulations, with varied composite beam parameters. The proposed design loads are less conservative than earlier estimates and deviate less from the simulations.

• Computers and Concrete
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• v.13 no.2
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• pp.235-253
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• 2014

The theoretical basis and the main results of a design procedure, which attempts to provide the optimal layout of ordinary reinforcement in prestressed concrete beams, subjected to bending moment and shear force are presented. The difficulties encountered in simulating the actual behaviour of prestressed concrete beam in presence of coupled forces bending moment - shear force are discussed; particular emphasis is put on plastic models and stress fields approaches. A unified model for reinforced and prestressed concrete beams under axial force - bending moment - shear force interaction is provided. This analytical model is validated against both experimental results collected in literature and nonlinear numerical analyses. Finally, for illustrating the applicability of the proposed procedure, an example of design for a full-scale prestressed concrete beam is shown.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.201-204
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• 2008

The Sectional Design Model(AASHTO LRFD) is appropriate for the design of typical bridge girders, slabs, and other regions of components where the assumptions of traditional engineering beam theory are valid. The shear resistance of a concrete member may be separated into a component, $V_c$, that relies on tensile stresses in the concrete, $V_s$, that relies on tensile stresses in the transverse reinforcement. The expressions for $V_c$ and $V_s$ apply to both prestressed and nonprestressed section, with the terms ${\beta}$ and ${\theta}$ depending on the applied loading(M, V, N, and T) and the properties of the section. With ${\beta}$ taken as 2.0 and ${\theta}$ as 45$^{\circ}$, the expressions for shear strength become essentially identical to those traditionally used for evaluating shear resistance. Recent large-scale experiments, however, have demonstrated that these traditional expression can be seriously unconservative for large members not containing transverse reinforcement. And This paper can present only a brief introduction to shear design of AASHTO LRFD and is to review of the technical difficulty.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2004.04a
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• pp.487-494
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• 2004

Resizing techniques have been recognized as practical methods for drift design of high-rise building since sensitivity analysis and iterative structural analysis are not required in implementation. In the techniques, the amount of material of a memberin a building for resizing is determined in terms of cross-sectional areas and sectional inertia moments as design variables. In this study, five drift design methods are developed by considering design variable linking strategy and fomulating resizing algorithm in terms of material properties of shear walls as a design variable. The developed methods are applied to the drift design of 20-story frame-RC shear wall structure, and then evaluated in the view points of practicality and efficiency.