scholarly journals Experimental Study on the Temperature Distribution and Residual Strength of Fire-damaged RC Columns Depending on Heated Areas

2020 ◽  
Vol 20 (3) ◽  
pp. 75-80
Author(s):  
Eunmi Ryu ◽  
Heesun Kim ◽  
Yeongsoo Shin
Keyword(s):  
Temperature Distribution ◽  
Residual Strength ◽  
Axial Loading ◽  
Concrete Columns ◽  
Structural Performance ◽  
Test Results ◽  
Floor Plan ◽  
Heated Area ◽  
Actual Fire ◽  
Asymmetric Heating

Most of the columns in actual fire conditions are heated on partial faces rather than all four sides due to the floor plan, which results in asymmetric behaviors of columns. The asymmetric behaviors of fire-damaged columns may cause more vulnerability to the structural performance. In this study, temperature distribution and residual strength of reinforced concrete columns exposed to fire were investigated according to various heated areas. To achieve the objective, columns were heated for 2 h according to ISO-834 standard time-temperature curve and subsequently tested under the axial loading after a week. The test results show that the residual strength of the fire-damaged columns decreased as the heated area increased, and the residual strength reduced additionally due to asymmetric heating.

scholarly journals Behaviour of hybrid concrete columns under axial compression loads

2018 ◽  
Vol 162 ◽  
pp. 04021
Author(s):  
Ali Resheq
Keyword(s):  
Ultimate Strength ◽  
Axial Compression ◽  
Axial Loading ◽  
Concrete Columns ◽  
Diameter Ratio ◽  
Concrete Column ◽  
Test Results ◽  
Column Length ◽  
Normal Concrete ◽  
Inner Diameter

Hybrid Concrete Column (HCC) is composite column consists of two types of concrete, Normal Concrete (NC) and Self Compacted Concrete (SCC). The main objective of this work is to study the effect of outer to inner diameter ratio of hybrid concrete on the ultimate strength of column under the axial loading. Ten scaled columns (150 mm diameter and 600 mm length) were fabricated and cast with different ratio of NC to SCC and tested under axial loading. The test results were presented in term of loading and the axial and lateral strains at mid span of column length. It was found that the ultimate strength of column increased from 281 kN to 605 kN (215%). Also it was found that the strength of column increased when the SCC is in inner thickness rather than in outer thickness of the column and the strength increased with increasing the inner thickness of SCC.

scholarly journals An experimental study on the structural performance of reinforced concrete low-rise building columns subjected to axial loading

2020 ◽  
Vol 14 (1) ◽  
pp. 103-111
Author(s):  
Pham Xuan Dat ◽  
Nguyen Anh Vu
Keyword(s):  
Reinforced Concrete ◽  
Axial Load ◽  
Load Capacity ◽  
Axial Loading ◽  
Structural Performance ◽  
Building Structures ◽  
Test Results ◽  
Structural Elements ◽  
Axial Load Capacity ◽  
Geometrical Dimensions

It has been commonly recognized by the international research and practice community that the presence of both outer and inner stirrups may significantly enhance the axial load capacity of reinforced concrete (RC) columns. However, there is limited testing evidence to support this conclusion that has been published nationally. This paper reports an experimental programme to study the effectiveness of stirrup detailing on the structural performance of columns having small sectional dimensions that are common in low-rise building structures. Nine column specimens with the same geometrical dimensions of 220 mm x 220 mm x 880 mm in three batches were detailed with different stirrup categories, have been gradually axially loaded to failure. The test data have revealed that although the presence of stirrups can generally enhance the axial load capacity of the column specimens, the enhancing levels are much dependent to the shapes of the stirrups. Selected interesting aspects of the test results have also been discussed, which set a concrete base for recommendations for design and detailing of such vertical structural elements. Keywords: experimental investigation; low-rise building columns; axial load capacity; stirrups.

Experimental study of moment carrying behavior of typical Tibetan timber beam-column joints

2021 ◽  
pp. 136943322110015
Author(s):  
Ting Guo ◽  
Na Yang ◽  
Huichun Yan ◽  
Fan Bai
Keyword(s):  
Bending Moment ◽  
Structural Performance ◽  
Test Results ◽  
Timber Beam ◽  
Rotational Stiffness ◽  
Trilinear Model ◽  
Column Joint ◽  
Loading Tests ◽  
The Moment ◽  
Relationship Of

This study aimed to investigate the moment carrying behavior of typical Tibetan timber beam-column joints under monotonic vertical static load and also evaluate the influence of length ratio of Gongmu to beam (LRGB) and dowels layout on the structural performance of the joint. Six full-scale specimens were fabricated with same construction but different Gongmu length and dowels position. The moment carrying performance of beam-column joints in terms of failure mode, moment resistance, and rotational stiffness of joints were obtained via monotonic loading tests. Test results indicated that all joints are characterized by compressive failure perpendicular to grain of Ludou. Additionally, it was found that greater LRGB leads to greater initial rotational stiffness and maximum moment of the joint by an increase of restraint length for beam end; however, offsetting dowels toward column resulted smaller stiffness and ultimate bending moment of joints, particularly, offsetting Beam-Gongmu dowels toward column changed the moment-rotation curve pattern of the beam-column joint, accompanied by a hardening stiffness at last phase. Furthermore, a simplified trilinear model was proposed to represent the moment-rotation relationship of the typical Tibetan timber beam-column joint.

Debonding Behaviors of CFRP Strengthened RC Beams with Weak Interfaces

2013 ◽  
Vol 351-352 ◽  
pp. 587-591
Author(s):  
Sen Li ◽  
Xiao Gang Wang ◽  
Xin Gang Zhou
Keyword(s):  
Tensile Strain ◽  
Structural Integrity ◽  
Structural Performance ◽  
Rc Beams ◽  
Test Results ◽  
Weak Interface ◽  
Premature Rupture ◽  
Loading Process ◽  
Interface Effects

Debonding behaviors of CFRP strengthened RC beams were experimentally investigated under the influence of weak interfaces, which are induced either by defective bonding of replaced cover or expansive cracks. Shown by test results, weak interfaces impaired considerably the structural integrity of strengthening systems during loading, and easily led to CFRP debonding failure. U-strips worked effectively in preventing the integral debonding and guarantee the structural performance of flexural sheets. However, local cover delamination in the loading process and premature rupture of flexural CFRP could still take place due to the weak interface effects. Therefore, allowable tensile strain of flexural CFRP should be reduced, and more strict confinement and anchorage measures should be taken in this case.

scholarly journals Sulfate and Calcium Chloride Resistance of Steel/Glass Fiber-Reinforced Polymer Hybrid Panel for Improved Movable Weir Application

2017 ◽  
Vol 2017 ◽  
pp. 1-14 ◽  
Author(s):  
S.-K. Lee ◽  
S.-Y. Yoo ◽  
C.-G. Park
Keyword(s):  
Glass Fiber ◽  
Calcium Chloride ◽  
Residual Strength ◽  
Fiber Reinforced Polymer ◽  
Test Results ◽  
Glass Fiber Reinforced Polymer ◽  
Sand Blasting ◽  
Steel Panel ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced

This study evaluated the performance of a hybrid panel that can overcome the current problem of corrosion of the steel panels of improved movable weirs when they are exposed to a sulfate and calcium chloride environment such as sea water. A hybrid panel with glass fiber-reinforced polymer (GFRP) layers on both sides of a steel panel means that the central panel is not exposed to the external elements, which can avoid corrosion problems. In this study, to maximize the hybrid panel’s strength and durability, the moisture absorption characteristics and the durability in an accelerated environment were evaluated. The test results were considered to indicate no durability issues as the final absorption ratio was approximately 2.0% or less in all environments. Also, from the accelerated deterioration test results when the steel panel processed by sand blasting was applied in all accelerated deterioration environments, it satisfied the residual strength level of 65% or more. However, in the case without surface processing, upon exposure to MgSO4 solution, it did not satisfy the standard residual strength level of 65%. These results show that sand blasting on the surface of a steel panel is adequate for hybrid panels for improved movable weirs.

scholarly journals Experimental Study on the Cyclic Performance of Reinforced Concrete Shear Walls Exposed to Fire

2020 ◽  
Vol 14 (1) ◽  
Author(s):  
Eunmi Ryu ◽  
Heesun Kim ◽  
Yeongsoo Shin
Keyword(s):  
Temperature Distribution ◽  
Aspect Ratio ◽  
Failure Mode ◽  
Failure Modes ◽  
Shear Walls ◽  
Lateral Loads ◽  
Cyclic Performance ◽  
Concrete Wall ◽  
Aspect Ratios ◽  
Heated Area

AbstractThe purpose of this study was to investigate the thermal and cyclic behaviors of fire-damaged walls designed with different failure modes, aspect ratios and heated areas. These cyclic behaviors include temperature distribution, maximum lateral load, stiffness, ductility, and energy dissipations, etc. Toward this goal, the concrete wall specimens were exposed to heat following an ISO 834 standard time–temperature curve and the cyclic loading was applied to the fire-damaged walls. The test results showed that exposure to fire significantly reduced the cyclic performance of the RC walls. Especially, it was observed that heated area, designed failure mode, and aspect ratio have influences on maximum lateral loads, stiffness, and ductility of the fire-damaged walls, while almost no effects of the heated area, designed failure mode, and aspect ratio on temperature distribution and energy dissipation were found.

Influence of loading rate on the capacity of a model pile in clay

1995 ◽  
Vol 32 (2) ◽  
pp. 364-368 ◽  
Author(s):  
Robert G. Horvath
Keyword(s):  
Loading Rate ◽  
Axial Loading ◽  
Displacement Transducer ◽  
Test Methods ◽  
Point Load ◽  
Test Results ◽  
Loading Test ◽  
Normal Loading ◽  
Model Pile ◽  
Rate Of Loading

Loading tests were carried out on a model pile embedded in clay to examine the influence of rate of loading on the capacity of the pile. The pile was loaded to failure using constant rate of penetration (CRP), quick maintained loading (QML), and quick continuous loading (QCL) methods of loading. The QCL test models the Statnamic loading test, which has been recently developed in Canada. The CRP tests were used as a reference, and the results were normalized using the CRP test results. The durations of the QML and QCL tests varied from approximately 0.1 s to 17 min, which are significantly faster than normal loading rates. Applied loads and point load were measured using load cells, and top displacement was measured using a displacement transducer. The test results showed an increase in pile capacity with increased rate of loading. Damping was found to be significant for the QCL tests (duration = 0.1 s) and negligible for the QML tests (duration ≥ 10 s). Correcting the results of the QCL tests for damping, using the equilibrium point method developed for Statnamic testing, greatly improved the correlation of the QCL and QML test results. Key words : model piles, axial loading, loading rate, clay, laboratory study, test methods.

scholarly journals Behavior of Columns Confined With FRP Fabrics under Repeated Lateral Loads

2019 ◽  
pp. 1-19
Author(s):  
Hesham A. Haggag ◽  
Nagy F. Hanna ◽  
Ghada G. Ahmed
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Axial Load ◽  
Axial Loading ◽  
Concrete Columns ◽  
Fiber Reinforced Polymers ◽  
Lateral Loads ◽  
Reinforced Concrete Columns ◽  
Reinforced Polymers ◽  
Axial Capacity

The axial strength of reinforced concrete columns is enhanced by wrapping them with Fiber Reinforced Polymers, FRP, fabrics.  The efficiency of such enhancement is investigated for columns when they are subjected to repeated lateral loads accompanied with their axial loading.  The current research presents that investigation for Glass and Carbon Fiber Reinforced Polymers (GFRP and CFRP) strengthening as well.  The reduction of axial loading capacity due to repeated loads is evaluated. The number of applied FRP plies with different types (GFRP or CFRP) are considered as parameters in our study. The study is evaluated experimentally and numerically.  The numerical investigation is done using ANSYS software. The experimental testing are done on five half scale reinforced concrete columns.  The loads are applied into three stages. Axial load are applied on specimen in stage 1 with a value of 30% of the ultimate column capacity. In stage 2, the lateral loads are applied in repeated manner in the existence of the vertical loads.  In the last stage the axial load is continued till the failure of the columns. The final axial capacities after applying the lateral action, mode of failure, crack patterns and lateral displacements are recorded.   Analytical comparisons for the analyzed specimens with the experimental findings are done.  It is found that the repeated lateral loads decrease the axial capacity of the columns with a ratio of about (38%-50%).  The carbon fiber achieved less reduction in the column axial capacity than the glass fiber.  The column confinement increases the ductility of the columns under the lateral loads.

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