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Responses of Concrete-Filled Cold-Formed Square Hollow and Double-C Steel Stub Columns under Cyclic and Repeated Loadings
No full textThis paper presents an experimental study on the response of 18 concrete-filled cold-formed square hollow and double-C steel stub columns under cyclic and repeated loading. The test parameters were (1) infilled materials, i.e. No fill, concrete infilled and mortar infilled columns (2) cross sectional shape and dimension. The effect of lips in double-c section as inside stiffeners is presented. The cyclic tested results indicate the infilled columns possess higher bearing capacity, especially infilled materials with higher strength and non-compact section columns. However, there is no different in ultimate tensile. Moreover, the infilled columns showed larger area under post-yield hysteretic loops leading to better seismic performance. Failure of columns was modified in which the failure mode was shifted from the in-outward local buckling into the outward manner, consequently resulted to higher bearing capacity.</jats:p
CAPACITY DESIGN CRITERIA FOR SEISMIC RESISTANCE OF PRECAST CONCRETE COLUMNS USING STEEL BOX CONNECTION
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Buckling Performance of Irregular Section Cold-Formed Steel Columns under Axially Concentric Loading
No full textThis paper presents experimental investigation and
finite element analysis on buckling behavior of irregular section coldformed
steel columns under axially concentric loading. For the
experimental study, four different sections of columns were tested to
investigate effect of stiffening and width-to-thickness ratio on
buckling behavior. For each of the section, three lengths of 230, 950
and 1900 mm. were studied representing short, intermediate long and
long columns, respectively. Then, nonlinear finite element analyses
of the tested columns were performed. The comparisons in terms of
load-deformation response and buckling mode show good agreement
and hence the FEM models were validated. Parametric study of
stiffening element and thickness of 1.0, 1.15, 1.2, 1.5, 1.6 and 2.0
mm. was analyzed. The test results showed that stiffening effect pays
a large contribution to prevent distortional mode. The increase in wall
thickness enhanced buckling stress beyond the yielding strength in
short and intermediate columns, but not for the long columns
Seismic performance of interior precast concrete beam-column connections with T-section steel inserts under cyclic loading
No full textResidual Strength of Reinforced Concrete Beams under Sequential Small Impact Loads
Get PDFSequential small impact loads may not collapse structures directly but could weaken the strength of structures. This study aimed to investigate the impact of these sequential small impact loads on the strength of the reinforced concrete beams. First, six sequential impact loads were applied to the test specimens. Then, the residual static capacity of the impacted specimens was determined by the ultimate static load test, compared with those of undamaged specimens. The experiment was composed of 12 specimens having identical dimensions. The variable parameters were the magnitude of the axial load and shear reinforcement. Under the sequential small impacts, the axial load improves the impact performance. It reduces the tensile strain of the longitudinal reinforcement. Hence, the flexural tensile crack propagation is limited. In addition, the local damage at the impact location is minimized and the shear plug induced diagonal shear crack is prevented. The axial force is also able to diminish the adverse effect of the large spacing stirrups. Large impact load could alter the failure of a designed flexural critical reinforced concrete beam without axial load to the shear failure. Although the axial load improves the impact response, the Residual Resistance Index (RRI) decreases with axial load. For the damaged specimens with axial load, the ultimate static load is lower than the calculated concrete shear capacity and more severe diagonal shear cracks were found. It can be obviously said that the prior impact damage decreases the concrete shear capacity
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Tests of Inclined Concrete-Filled Steel Tubular Stub Columns under Vertical Cyclic Loading
No full textThis paper presents an experimental study on the cyclic behavior of fifteen concrete-filled steel tubular columns subjected to vertical cyclic loading. All test samples’ cross-sectional area is 75 × 75 mm2 square, and they are 500 mm long. The main variables in the test are the thickness of the steel tube (1.8 and 3.0 mm with the width-to-thickness ratios (b/t) of 41.7 and 25), the strength of the infilled concrete (no-fill, 23 MPa, and 42 MPa), and the inclined angle (0, 4, and 9 degrees). The results show that all samples failed due to local buckling in compression followed by tearing of the steel tube in tension. The inclination angles of 4 and 9 degrees decreased the vertical compressive capacity of the 1.8 mm vertical hollowed steel column by 34 and 39 percent, respectively. However, the infilled concrete and thicker tube (3.0 mm) could substantially reduce the adverse effect of the inclination angle. The compressive ductility of the hollowed column with the thinner tube was significantly enhanced by the infilled concrete as well
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