• Earthquakes and Structures
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• v.10 no.2
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• pp.351-366
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• 2016

The structural collapse of masonry structure under dynamic loading displays many possible failure mechanisms often related to interaction between structural components. Roof collapse is one of the major damage mechanisms observed in masonry structures during an earthquake. Better connection between the roof diaphragm and walls may be preventing roof collapse, but it can affect other failure mechanisms. In spite of this fact, less attention has been paid to the influence of the roof diaphragm effect on masonry structures and little research has been implemented in this field. In the present study, the roof diaphragm effect on the unreinforced masonry structure under dynamic loading has been experimentally investigated. Three one-quarter scale one-story adobe masonry house models with different roof conditions have been tested by subjecting them to sinusoid loading on a shaking table simulator. Phenomena such as failure pattern, dynamic performance of masonry structure were examined.

• Carbon letters
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• v.5 no.1
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• pp.18-22
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• 2004

The failure behaviours of unidirectional pultruded carbon fiber reinforced polymer (CFRP) composites were monitored by the electrical resistance measurement during tensile loading, three-point-bending, interlaminar shear loading. The tensile failure behaviour of carbon fiber tows was also investigated by the electrical resistance measurement. Infrared thermography non-destructive evaluation was performed in real time during tensile test of CFRP composites to validate the change of microdamage in the materials. Experiment results demonstrated that the CFRP composites and carbon fiber tows were damaged by different damage mechinsms during tensile loading, for the CFRP composites, mainly being in the forms of matrix damage and the debonding between matrix and fibers, while for the carbon fiber tows, mainly being in the forms of fiber fracture. The correlation between the infrared thermographs and the change in the electrical resistance could be regarded as an evidence of the damage mechanisms of the CFRP composites. During three-point-bending loading, the main damage forms were the simultaneity fracture of matrix and fibers firstly, then matrix cracking and the debonding between matrix and fiber were carried out. This results can be shown in Fig. 9(a) and (b). During interlaminar shear loading, the change in the electrical resistance was related to the damage degree of interlaminar structure. Electrical resistance measurement was more sensitive to the damage behaviour of the CFRP composites than the stress/time curve.

• Steel and Composite Structures
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• v.11 no.1
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• pp.39-58
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• 2011

The subject of the ongoing research work is to analyze the composite action of the structural elements of composite slabs with profiled steel decking by experimental and numerical studies. The mechanical and frictional interlocks result in a complex behaviour and failure under horizontal shear action. This is why the design characteristics can be determined only by standardized experiments. The aim of the current research is to develop a computational method which can predict the behaviour of embossed mechanical bond under shear actions, in order to derive the design characteristics of composite slabs with profiled steel decking. In the first phase of the research a novel experimental analysis is completed on an individual concrete encased embossment of steel strip under shear action. The experimental behaviour modes and failure mechanisms are determined. In parallel with the tests a finite element model is developed to follow the ultimate behaviour of this type of embossment, assuming that the phenomenon is governed by the failure of the steel part. The model is verified and applied to analyse the effect of embossment's parameters on the behaviour. In the extended investigation different friction coefficients, plate thicknesses, heights and the size effects are studied. On the basis of the results the tendencies of the ultimate behaviour and resistance by the studied embossment's characteristics are concluded.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.375-381
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• 2008

This paper deals with the shear capacity of corrugated rib as the shear connector in composite structures. Corrugated rib is modified as perfobond rib shear connector type to evaluate the shear capacity. A total 12 push-out specimens with stud, perfobond rib, and corrugated rib connector were fabricated. Then, the influences of hole-crossing bars, concrete dowel, depth of corrugated panel and height of rib on the shear capacity were evaluated experimentally. As the results of these tests, the failure mechanisms of corrugated rib and perfobond rib specimens were associated with the bearing failure of the concrete slabs, but the failure of weld zone did not occur. The shear capacity of corrugated rib specimens improved as high to 96% compared to the perfobond rib shear connectors. Also, the hole-crossing bars were effective on the improvement of concrete dowel action, and consequently, shear capacity increased by 48%. It was also proven that the increment of the depth of corrugated panel and the height of rib increased the concrete bearing resistance, therefore increasing the shear capacity.

• Computers and Concrete
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• v.21 no.3
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• pp.335-344
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• 2018

More and more special-shaped structural systems have been widely used in various industrial and civil buildings in order to satisfy the new structural system and the increasing demand for architectural beauty. With the popularity of the special-shaped structure system, its seismic performance and damage form have also attracted extensive attention. In the current research, an experimental analysis of six groups of (2/3 scale) T-shaped column joints was conducted to investigate the seismic performance of T-shaped column joints. Effects of the beam cross section, transverse stirrup ratio and axial compression ratio on bearing capacity and energy dissipation capacity of column joints were obtained. The crack pattern of T-shaped column joints under low cyclic load was presented and showed a reversed "K" mode. According to the crack configurations, a tensile-shear failure model to determine the shear bearing capacity and crack propagation mechanisms is developed.

• Korean Journal of Metals and Materials
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• v.46 no.8
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• pp.524-537
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• 2008

Zr-based amorphous alloy matrix composites reinforced with metallic continuous fibers were fabricated by liquid pressing process, and their fracture properties were investigated by directly observing microfracture process using an in situ loading stage installed inside a scanning electron microscope chamber. About 60 vol.% of metallic fibers were homogeneously distributed inside the amorphous matrix. Apparent fracture toughness of the stainless-steel- and tungsten-fiber-reinforced composites was lower than that of monolithic amorphous alloy, while that of the Ta-fiber-reinforced composite was higher. According to the microfracture observation, shear bands or cracks were initiated at the amorphous matrix, and the propagation of the initiated shear bands or cracks was effectively blocked by fibers, thereby resulting in stable crack growth which could be confirmed by the fracture resistance curve (R-curve) behavior. This increase in fracture resistance with increasing crack length improved fracture properties of the fiber-reinforced composites, and could be explained by mechanisms of formation of multiple shear bands or multiple cracks at the amorphous matrix and blocking of crack or shear band propagation and multiple necking at metallic fibers.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.48-53
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• 2000

The effects of added elements, such as Co or Nb, on wear properties of high speed steel by powder metallurgy(PM-HSS) had been evaluated in previous paper. The wear properties of materials, in fact, have been a]so influenced by heat-treating conditions. In this paper, the effects of heat-treating conditions on wear properties of PM-HSS have been evaluated. The wear tests have been performed as same conditions as previous paper using PM-HSS(5%Co-1%Nb) heat-treated under different quenching and tempering temperature. The result of this paper shows that wear resistance of PM-HSS is improved with relatively high quenching temperature. However tempering temperature is not sensitve to the wear resistance in range of high quenching temperature. It may be deduced by the fact that the shear strength of matrix by strengthening mechanisms of quenching aging in addition to dispersion-hardening is improved.

• Composites Research
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• v.16 no.2
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• pp.62-67
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• 2003

Interfacial properties and damage sensing for the carbon fiber/epoxy-amine terminated (AT)-polyetherimide (PEI) composite were performed using microdroplet test and electrical resistance measurements. As AT-PEI content increased, the fracture toughness of epoxy-AT-PEI matrix increased, and interfacial shear strength (IFSS) increased due to the improved fracture toughness by energy absorption mechanisms of AT-PEI phase. The microdroplet in the carbon fiber/neat epoxy composite showed brittle microfailure mode. At 15 phr AT-PEI content ductile microfailure mode appeared because of improved fracture toughness. After curing, the change in electrical resistance $\Delta\textrm{R}$) with increasing AT-PEI content increased gradually because of thermal shrinkage. Under cyclic stress, in the neat epoxy case the reaching time until same stress was faster and their slope was higher than those of 15 phr AT-PEI. The result obtained from electrical resistance measurements under curing process and reversible stress/strain was correspondence well with matrix toughness properties.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.35 no.5
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• pp.277-286
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• 2022

The elastic and inelastic responses obtained from the experimental and analytical results of two RC building structures under the service level earthquake (SLE) and maximum considered earthquake (MCE) in Korea were used to weinvestigate the characteristics of the mechanisms resisting shear and torsional behavior in torsionally unbalanced structures. Equations representing the interactive effect of translational drift and torsional deformation on the shear force and torsional moment were proposed. Because there is no correlation in the behavior between elastic and inelastic forces and strains, the incremental shear forces and incremental torsional moments were analyzed in terms of their corresponding incremental drifts and incremental torsional deformations with respect to the yield, unloading, and reloading phases around the maximum edge-frame drift. In the elastic combination of the two dominant modes, the translational drift mainly contributes to the shear force, whereas the torsional deformation contributes significantly to the overall torsional moment. However, this phenomenon is mostly altered in the inelastic response such that the incremental translational drift contributes to both the incremental shear forces and incremental torsional moments. In addition, the given equation is used to account for all phenomena, such as the reduction in torsional eccentricity, degradation of torsional stiffness, and apparent energy generation in an inelastic response.

• Structural Engineering and Mechanics
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• v.60 no.5
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• pp.781-794
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• 2016

Due to its relatively good safety performance and aesthetic benefits, laminated glass (LG) is increasingly being used as load-carrying members in modern buildings. This paper presents an experimental study into one applicational scenario of structural LG subjected to in-plane bending. The aim of the study is to reveal the in-plane behaviors of the LG beams made up of multi-layered glass sheets. The LG specimens respectively consisted of two, three and four plies of glass, bonded together by two prominent adhesives. A total of 26 tests were carried out. From these tests, the structural behaviors in terms of flexural stiffness, load resistance and post-breakage strength were studied in detail, whilst considering the influence of interlayer type, cross-sectional interlayer percentage and presence of shear forces. Based on the test results, analytical suggestions were made, failure modes were identified, corresponding failure mechanisms were discussed, and a rational engineering model was proposed to predict the post-breakage strength of the LG beams. The results obtained are expected to provide useful information for academic and engineering professionals in the analysis and design of LG beams bending in-plane.