• Earthquakes and Structures
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• v.16 no.3
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• pp.329-348
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• 2019

The main objective of this experimental research was to investigate the Seismic performance of reinforced concrete frames infilled with perforated clay brick masonry wall of a type commonly used in Algeria. Four one story-one bay reinforced concrete infilled frames of half scale of an existing building were tested at the National Earthquake Engineering Research Center Laboratory, CGS, Algeria. The experiments were carried out under a combined constant vertical and reversed cyclic lateral loading simulating seismic action. This experimental program was performed in order to evaluate the effect and the contribution of the infill masonry wall on the lateral stiffness, strength, ductility and failure mode of the reinforced concrete frames. Numerical models were developed and calibrated using the experimental results to match the load-drift envelope curve of the considered specimens. These models were used as a bench mark to assess the effect of normalized axial load on the seismic performance of the RC frames with and without masonry panels. The main experimental and analytical results are presented in this paper.

• Structural Engineering and Mechanics
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• v.27 no.6
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• pp.697-711
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• 2007

Though extensive research has been carried out for the ultimate strength of steel reinforced concrete (SRC) members under static and cyclic load, there was only limited information on the applied analysis models. Modeling of the inelastic response of SRC members can be accomplished by using a microcosmic model. However, generally used microcosmic model, which usually contains a group of parameters, is too complicated to apply in the nonlinear structural computation for large whole buildings. The intent of this paper is to develop an effective modeling approach for the reliable prediction of the inelastic response of SRC columns. Firstly, five SRC columns were tested under cyclic static load and constant axial force. Based on the experimental results, normalized trilinear skeleton curves were then put forward. Theoretical equation of normalizing point (ultimate strength point) was built up according to the load-bearing mechanism of RC columns and verified by the 5 specimens in this test and 14 SRC columns from parallel tests. Since no obvious strength deterioration and pinch effect were observed from the load-displacement curve, hysteresis rule considering only stiffness degradation was proposed through regression analysis. Compared with the experimental results, the applied analysis model is so reasonable to capture the overall cyclic response of SRC columns that it can be easily used in both static and dynamic analysis of the whole SRC structural systems.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.9
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• pp.1469-1476
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• 2003

This paper provides plastic limit load solutions of cylinders with circumferential part-through surface cracks under combined axial tension, internal pressure and global bending. Such solutions are developed based on detailed three-dimensional (3-D) finite element (FE) limit analyses using elastic-perfectly-plastic material behaviour, together with analytical solutions based on equilibrium stress fields. For the crack location, both external and internal cracks are considered. Furthermore, in terms of the crack shape, both semi-elliptical and constant-depth surface cracks are considered. The resulting limit load solutions are given in a closed form, and thus can be easily used in practical situations. Being based on detailed 3-D FE limit analysis, the present solutions are believed to most reliable, and thus to be valuable information for integrity assessment of piping.

• Journal of the Korea Concrete Institute
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• v.17 no.1 s.85
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• pp.113-120
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• 2005

The purpose of this study is to investigate the strength and ductility improvement of columns retrofitted by steel-fiber composite plate. Test specimens strengthened by three different materials - steel plate(SP), carbon fiber sheet(CF) and fiber-steel composite plate(CP) - were tested under cyclic lateral load with a constant axial load equal to $20\%$ of the axial compression capacity. The structural capacity of composite plate was good or better than that of other retrofitting materials. Test results from all retrofitted specimens showed that considerably higher retrofitting amount was required for strength enhancement. The ductility of retrofitted columns by composite plate was fairly improved. Also, energy ductility ratio was more effective than displacement ductility ratio for ductility estimation of retrofitted column.

• Journal of Korean Society of Steel Construction
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• v.22 no.6
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• pp.523-532
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• 2010

Concrete-filled square steel tube (CFT) columns have inherently high fire resistance and load-bearing capacity. Nevertheless, it is sometimes necessary to improve their fire resistance using external fire protection. This paper presents the experimental results of the temperature distribution of CFT columns with fire protection. A fire load test was carried out by exposing small-scale specimens to heat in an electric furnace that was especially built for testing loaded columns. The temperature distribution of CFT columns under constant axial loads was determined, as were its significant parameters, such as the types of fire protection and thickness, the thickness of the square CFT, and the fire duration times. The results of this study showed the temperature distribution of each specimen of the electric furnace and the temperature distribution properties of concrete and steel. In addition, the axial displacement and local buckling behavior of CFT columns based on temperature changes was observed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.71-82
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• 2013

Eight small scale circular reinforced concrete columns (4.5 aspect ratio) were tested under cyclic lateral load with constant axial load. The selected test variables are longitudinal steel ratio (2.017%, 3.161%), transverse steel ratio, and axial load ratio (0, 0.07, 0.15). Volumetric ratio of spirals of all the columns is 0.335~0.894% in the plastic hinge region. It corresponds to 39.7~122.3% of the minimum requirement of confining steel by Korean Bridge Design Specifications, which represent existing columns not designed by the current seismic design specifications or designed by seismic concept. The final objectives of this study are to provide quantitative reference data and tendency for performance or damage assessment based on the performance levels such as cracking, yielding, steel fracture, etc. In this paper, describes mainly failure behavior, strength degradation behaviour, displacement ductility of circular reinforced concrete bridge columns with respect to test variables.

• Journal of Korean Society of Steel Construction
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• v.9 no.2 s.31
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• pp.221-228
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• 1997

The main purpose of this paper is to determine the dynamic optimal shapes of simple beam-columns with the constant volume. The parabolic function is chosen as the variable equation for the depth of regular polygon cross-section. The ordinary differential equation including the effect of axial load is applied to calculate the natural frequencies. The Runge-Kutta and Regula-Falsi methods are used to integrate the differential equation and compute the frequencies, respectively. Then the dynamic optimal shape whose lowest natural frequency is highest is determined by reading the critical value of the frequency versus section ratio curve plotted by the frequency data. In the numerical examples, the simple beam-columns are analysed and the numerical results of this study are shown in tables and figures.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.533-538
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• 2006

This study deals with the static and dynamic stability analyses of simple tapered columns with constant volume. The crosssections of column taper are the regular polygons whose depths are varied with the parabolic functional fashion. The hingedhinged end constraint is chosen as the boundary condition of the column. The non-dimensional ordinary differential equation governing free vibrations of such column subjected to an axial load is derived and solved numerically. From numerical results, the relationships between natural frequencies and section ratios are obtained, from which the configurations of dynamic optimal shapes of columns and the strongest columns are extracted.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.493-494
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• 2009

Two strengthened columns and an unstrengthened control column were tested to failure under cyclic lateral load combined with a constant axial load to effect of anchorage of T-shaped steel plate in the strengthened column using wire rope units. Main variables considered were anchorage method of T-shaped steel plate. Tested columns were compared with those of conventionally tied columns tested by research of before. Test results showed that lateral load capacity and the displacement ductility ratio of anchorage of T-shaped steel plate in the strengthened column increased 40% and 130% than unstrengthened column, respectively. In particular, at the same effective lateral reinforcement index, a much ductility ratio was observed in the strengthened columns than in the tied columns.

• Journal of Korean Association for Spatial Structures
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• v.6 no.2 s.20
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• pp.93-105
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• 2006

In order to investigate the effect of the height of application point of lateral loads and reinforcing steel bars in walls and columns in improving the seismic behavior of confined concrete block masonry walls, an experimental research program is conducted. A total of twelve one-half scale specimens are tested under repeated lateral loads. Specimens are tested to failure with increasing maximum lateral drifts while a vertical axial load was applied and maintained constant. The specimens adopted are two-dimensional (2D) hollow concrete block masonry walls with different parameters such as shear span ratio, inflection point and percent of reinforcement in confining columns and walls. Test results obtained for each specimen include cracking patterns, load-deflection curve, and strains in reinforcement and walls in critical locations. Analysis of test data showed that above parameters generate a considerable effect on the seismic performance of confined concrete block masonry walls.