• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.234-237
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• 2006

A series of three shear wall specimens was tested under constant axial stress and reversed cyclic lateral loading in order to evaluate the seismic retrofit that had been proposed for the shear wall with the opening induced by remodeling. One of these specimens was tested in the as-built condition and the other two were retrofitted prior to testing. The retrofit involved the use of carbon fiber sheets and steel plates (thickness of 3mm) over the entire face of the wall. The test results show that the ultimate failure modes of the specimens were found to be shear fracture of the wall around the opening and two difference types of retrofitting strategy make the different effects of a rise in the strength of each specimen.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.53-56
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• 2005

This paper investigates the effect of ductile deformation behavior of high performance hybrid fiber-reinforced cement composites (HPHFRCCs) on the shear behavior of coupling beams to lateral load reversals. The matrix ductility and the reinforcement layout were the main variables of the tests. Three short coupling beams with two different reinforcement arrangements and matrixes were tested. They were subjected to cyclic loading by a suitable experimental setup. All specimens were characterized by a shear span-depth ratio of 1.0. The reinforcement layouts consisted of a classical scheme and diagonal scheme without confining ties. The effects of matrix ductility on deflections, strains, crack widths, crack patterns, failure modes, and ultimate shear load of coupling beams have been examined. The combination of a ductile cementitious matrix and steel reinforcement is found to result in improved energy dissipation capacity, simplification of reinforcement details, and damage-tolerant inelastic deformation behavior. Test results showed that the HPFRCC coupling beams behaved better than normal reinforced concrete control beams. These results were produced by HPHFRCC's tensile deformation capacity, damage tolerance and tensile strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.247-250
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• 2005

The aim of Cast-In-Place(CIP) method is to upgrade the strength, ductility and stiffness of the structure to the required level. The main objective of this research is to investigate the shear and the flexural strength of reinforced concrete frames infilled with CIP reinforced concrete wall. For this three 1/3 scale, one-bay, one story reinforced concrete infill wall were tested under reversed cyclic loading simulating the seismic effect. Results of tests of CIP shear wall were reviewed to evaluate the current design provisions and to establish the feasible retrofitting method.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.227-230
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• 2005

This paper provides a method to predict the ductile capacity of reinforced concrete beam-column joints that fail in shear after the plastic hinges occur at both ends of the adjacent beams. The proposed method takes into account shear strength deterioration in the beam-column joints. The shear strength and the corresponding ductility of the proposed method was verified by comparing with the four RC beam-column assembles under reversed cyclic loading corrected from the technical literature. Comparisons between the observed and calculated shear strengths and their corresponding ductilities of the tested assembles, showed reasonable agreement

• Steel and Composite Structures
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• v.28 no.5
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• pp.527-539
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• 2018

The use of reinforced concrete (RC) shear wall with concrete filled steel tube (CFST) columns and steel fiber reinforced concrete (SFRC) shear wall has aroused widespread attention in recent years. A new shear wall, named SFRC shear wall with CFST columns, is proposed in this paper, which makes use of CFST column and SFRC shear wall. Six SFRC shear wall with CFST columns specimens were tested under cyclic loading. The effects of test parameters including steel fiber volume fraction and concrete strength on the failure mode, strength, ductility, rigidity and dissipated energy of shear wall specimens were investigated. The results showed that all tested shear wall specimens exhibited a distinct shear failure mode. Steel fibers could effectively control the crack width and improve the distribution of cracks. The load carrying and energy dissipation capacities of specimens increased with the increase of steel fiber volume fraction and concrete strength, whilst the ductility of specimens increased with the increase of steel fiber volume fraction and the decrease of concrete strength.

• Steel and Composite Structures
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• v.28 no.5
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• pp.641-653
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• 2018

This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

• Steel and Composite Structures
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• v.39 no.4
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• pp.435-451
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• 2021

Shear lag effect was a significant mechanical behavior of steel-concrete composite beams, and the effective flange width was needed to consider this effect. However, the effective flange width is mostly determined by static load test. The cyclic vehicle loading cases, which is more practical, was not well considered. This paper focuses on the study of shear lag effect of the concrete slab in the negative moment region under fatigue cyclic load. Two specimens of two-span steel-concrete composite beams were tested under fatigue load and static load respectively to compare the differences in the negative moment region. The reinforcement strain in the negative moment region was measured and the stress was also analyzed under different loads. Based on the OpenSees framework, finite element analysis model of steel-concrete composite beam is established, which is used to simulate transverse reinforcement stress distribution as well as the variation trends under fatigue cycles. With the established model, effects of fatigue stress amplitude, flange width to span ratio, concrete slab thickness and shear connector stiffness on the shear lag effect of concrete slab in negative moment area are analyzed, and the effective flange width ratio of concrete slab under different working conditions is calculated. The simulated results of effective flange width are compared with calculated results of the commonly used specifications, and it is found that the methods in the specifications can better estimate the shear lag effect in concrete slab under static load, but the effective flange width in the negative moment zone under fatigue load has a large deviation.

• Steel and Composite Structures
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• v.46 no.4
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• pp.497-512
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• 2023

Using light weight concrete as infill material in conventional cold-formed steel (CFS) shear wall systems can considerably increase their load bearing capacity, ductility, integrity and fire resistance. The compressive strength of the filler concrete is a key factor affecting the structural behaviour of the composite wall systems, and therefore, achieving maximum compressive strength in lightweight concrete while maintaining its lightweight properties is of significant importance. In this study a new type of optimum polystyrene lightweight concrete (OPLC) with high compressive strength is developed for infill material in composite CFS shear wall systems. To study the seismic behaviour of the OPLC-filled CFS shear wall systems, two full scale wall specimens are tested under cyclic loading condition. The effects of OPLC on load-bearing capacity, failure mode, ductility, energy dissipation capacity, and stiffness degradation of the walls are investigated. It is shown that the use of OPLC as infill in CFS shear walls can considerably improve their seismic performance by: (i) preventing the premature buckling of the stud members, and (ii) changing the dominant failure mode from brittle to ductile thanks to the bond-slip behaviour between OPLC and CFS studs. It is also shown that the design equations proposed by EC8 and ACI 318-14 standards overestimate the shear force capacity of OPLC-filled CFS shear wall systems by up to 80%. This shows it is necessary to propose methods with higher efficiency to predict the capacity of these systems for practical applications.

• Geomechanics and Engineering
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• v.10 no.2
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• pp.189-205
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• 2016

Soils are subjected to additional stresses due to the loads transferred by the foundations of the buildings. The distribution of stress in soil has great importance in geotechnical engineering projects such as stress, settlement and liquefaction analyses. The purpose of this study is to examine the shear stresses on horizontal plane below the rectangular foundations subjected to biaxial bending on an elastic soil. In this study, closed-form analytical solutions for shear stresses in x and y directions were obtained from Boussinesq's stress equations. The expressions of analytical solutions were simplified by defining the shear stress influence values ($I_1$, $I_2$, $I_3$), and solution charts were presented for obtaining these values. For some special loading conditions, the expressions for shear stresses in the soil below the corners of a rectangular foundation were also given. In addition, a computer program was developed to calculate the shear stress increment at any point below the rectangular foundations. A numerical example for illustrating the use of the presented solution charts was given and, finally, shear stress isobars were obtained for the same example by a developed computer program. The shear stress expressions obtained in this work can be used to determine monotonic and cyclic behavior of soils below rectangular foundations subjected to biaxial bending.

• Steel and Composite Structures
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• v.30 no.5
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• pp.443-456
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• 2019

Although numerous researchers demonstrated the significant difference in performance between the various beam-to-column connection types, most of the previous studies in the area of infilled steel frames focused on the behaviour of frames with welded connections. Therefore, there is a need for conducting studies on infilled steel frames with other common connection types (extended endplate with and without rib stiffeners, flush endplate and shear connections). In this paper, firstly, a two-dimensional finite-element model simulating the cyclic response of infilled steel frames was presented. The infill-frame interaction, as well as the interactions between connections' components, were properly modelled. Using the previously-validated model, a parametric study on infilled steel frames with five different beam-to-column connection types, under cyclic loading, was carried out. Several parameters, including infill material, fracture energy of masonry and infill thickness, were investigated. The results showed that the infilled frames with welded connections had the highest initial stiffness and load-carrying capacity. However, the infilled frames with extended endplate connections (without rib stiffeners) showed the greatest energy dissipation capacity and about 96% of the load-carrying capacity of frames with welded connections which indicates that this type of connection could have the best performance among the studied connection types. Finally, a simplified analytical model for estimating the stiffness and strength of infilled steel frames (with different beam-to-column connection types) subjected to lateral cyclic loading, was suggested.