scholarly journals Fire Performance of Columns Made of Normal and High Strength Concrete: A Comparative Analysis

2016 ◽  
Vol 711 ◽  
pp. 564-571 ◽  
Author(s):  
Thomas Gernay
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Strength Loss ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Strength Concrete ◽  
The Impact

The use of high strength concrete (HSC) in multi-story buildings has become increasingly popular. Selection of HSC over normal strength concrete (NSC) allows for reducing the dimensions of the columns sections. However, this reduction has consequences on the structural performance in case of fire, as smaller cross sections lead to faster temperature increase in the section core. Besides, HSC experiences higher rates of strength loss with temperature and a higher susceptibility to spalling than NSC. The fire performance of a column can thus be affected by selecting HSC over NSC. This research performs a comparison of the fire performance of HSC and NSC columns, based on numerical simulations by finite element method. The thermal and structural analyses of the columns are conducted with the software SAFIR®. The variation of concrete strength with temperature for the different concrete classes is adopted from Eurocode. Different configurations are compared, including columns with the same load bearing capacity and columns with the same cross section. The relative loss of load bearing capacity during the fire is found to be more pronounced for HSC columns than for NSC columns. The impact on fire resistance rating is discussed. These results suggest that consideration of fire loading limits the opportunities for use of HSC, especially when the objective is to reduce the dimensions of the columns sections.

Comparative Analysis of Axially Loaded Composite Columns

2011 ◽  
Vol 147 ◽  
pp. 99-104 ◽  
Author(s):  
Moftah Almadini ◽  
Dusan Kovacevic ◽  
Vlastimir Radonjanin
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
High Strength ◽  
Light Weight ◽  
Steel Tubes ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Composite Columns ◽  
Strength Concrete ◽  
Light Weight Concrete

Experiments on square and circular steel columns filled with light-weight concrete and high strength concrete have been conducted to investigate the contribution of these types of concrete to load bearing capacity of short composite columns. The aim of this research was to determine the effect of two types of concrete filling on behaviour of the composite columns. Thirteen specimens were divided in two groups: steel tubes filled with different type of concrete, with or without reinforcement and RC columns with same dimensions and shape, made of same type of concrete. Comparison was made between load bearing capacity of the steel tubes filled with light-weight concrete, and high strength concrete (with and without reinforcement). All specimens were tested by axial compression until to the failure state realization. Factors which influence the behavior and failure mode, ultimate strength, deflections and stress-strain relation were discussed.

scholarly journals TESTS ON 10.9 BOLTS UNDER COMBINED TENSION AND SHEAR DURING AND AFTER FIRE

2016 ◽  
Author(s):  
Anne K. Kawohl ◽  
Jörg Lange
Keyword(s):  
Bearing Capacity ◽  
Elevated Temperatures ◽  
High Strength ◽  
Preliminary Test ◽  
Test Series ◽  
Fire Performance ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Set Up ◽  
Fire Conditions

Prior investigations of the load bearing capacity of bolts during fire have shown differing behaviour between bolts that were loaded by shear or by tensile loads. The interaction of the two loads has not yet been examined under fire conditions. This paper describes a preliminary test series on the post-fire performance of high-strength bolts of the property class 10.9 under combined tension and shear. The results show that how the bolt is loaded influences the load bearing capacity. It is assumed that this is also true at elevated temperatures. Further, atest set-up for experiments at elevated temperatures and a more detailed test series on the post-fire performance under combined tension and shear is presented.

Study on the Influence Factors of Bearing Capacity of the Fiber Reinforced High Strength Concrete Three-Pile Caps

2010 ◽  
Vol 163-167 ◽  
pp. 1586-1591
Author(s):  
Jie Lei ◽  
Dan Ying Gao ◽  
Hua Fan
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Concrete Strength ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Strength Concrete ◽  
Pile Caps

Based on the experiments of 10 model specimens of fiber reinforced high strength concrete three-pile caps with the dimension of 831mm×831mm×831mm, the mechanical behavior and the important factors on the cracking load and ultimate bearing capacity of fiber reinforced high strength concrete three-pile caps were researched. The study indicates that with increasing of concrete strength, the volume fraction of steel fiber, the effective thickness and reinforcement ratio of pile cap, the bearing capacity of three-pile caps improves largely. At the same time the type of steel fiber and steel ratio have remarkable effects on the bearing capacity. The results are valuable for establishing bearing capacity calculation formulas of fiber reinforced high strength concrete three-pile caps and improving “the Technical Specification for fiber Reinforced Concrete Structure.”

scholarly journals Concrete-filled round-ended steel tubular stub columns under concentric and eccentric loads

2018 ◽  
Author(s):  
Ana Piquer Vicent ◽  
David Hernández-Figueirido ◽  
Carmen Ibáñez Usach
Keyword(s):  
Bearing Capacity ◽  
Mechanical Behaviour ◽  
Mechanical Response ◽  
Concrete Strength ◽  
High Strength ◽  
Load Bearing Capacity ◽  
Cross Sectional ◽  
Load Bearing ◽  
Composite Columns ◽  
Stub Columns

In the past, many works to study the mechanical behaviour of concrete filled steel tubular (CFST) stub columns have been conducted. Some of the applications of these composite columns oblige to meet higher requirements of ductility and load-bearing capacity. Traditionally, circular and rectangular tubes have been employed but recently new cross-sectional shapes of these composite columns are being designed and investigated with the aim of optimizing their mechanical behaviour. In this line, concrete-filled round-ended steel tubular columns (CFRT) have appeared as an alternative. However, the number of experimental programs to characterize their mechanical response is still scarce. In order to contribute to the test results database, in this paper an experimental study of 9 concrete-filled round-ended steel tubular stub columns is presented. All the specimens were designed with the same cross-sectional round-ended shape and have the same dimensions. In this program, both normal and high-strength concrete were employed as infill. During the tests, the columns were subjected to axial compression loads but under different eccentricities. The influence of eccentricity and concrete strength on the ultimate load bearing capacity of the concrete-filled round-ended steel tubular are discussed. Besides, the combined action of both components in this type of concrete-filled tubes as well as the effect of the concrete infill are studied.

scholarly journals Experimental Study on the Torsional Behaviour of Prestressed HSC Hollow Beams

2020 ◽  
Vol 10 (2) ◽  
pp. 642 ◽  
Author(s):  
Luís Bernardo ◽  
Sérgio Lopes ◽  
Mafalda Teixeira
Keyword(s):  
Experimental Study ◽  
High Strength Concrete ◽  
Concrete Beams ◽  
Concrete Strength ◽  
High Strength ◽  
Experimental Program ◽  
Pure Torsion ◽  
Strength Concrete ◽  
Hollow Beams

This article describes an experimental program developed to study the influence of longitudinal prestress on the behaviour of high-strength concrete hollow beams under pure torsion. The pre-cracking, the post-cracking and the ultimate behaviour are analysed. Three tests were carried out on large hollow high-strength concrete beams with similar concrete strength. The variable studied was the level of longitudinal uniform prestress. Some important conclusions on different aspects of the beams’ behaviour are presented. These conclusions, considered important for the design of box bridges, include the influence of the level of prestress in the cracking and ultimate behaviour.

Bond behavior of high strength concrete under reversed pull-out cyclic loading

2002 ◽  
Vol 29 (2) ◽  
pp. 191-200 ◽  
Author(s):  
M Alavi-Fard ◽  
H Marzouk
Keyword(s):  
Cyclic Loading ◽  
Bond Strength ◽  
High Strength Concrete ◽  
Concrete Strength ◽  
High Strength ◽  
Displacement Curve ◽  
Bond Slip ◽  
Strength Concrete ◽  
Pull Out ◽  
Normal Strength

Structures located in seismic zones require significant ductility. It is necessary to examine the bond slip characteristics of high strength concrete under cyclic loading. The cyclic bond of high strength concrete is investigated under different parameters, including load history, confining reinforcement, bar diameter, concrete strength, and the rate of pull out. The bond strength, cracking, and deformation are highly dependent on the bond slip behavior between the rebar and the concrete under cyclic loading. The results of cyclic testing indicate that an increase in cyclic displacement will lead to more severe bond damage. The slope of the bond stress – displacement curve can describe the influence of the rate of loading on the bond strength in a cyclic test. Specimens with steel confinement sustained a greater number of cycles than the specimens without steel confinement. It has been found that the maximum bond strength increases with an increase in concrete strength. Cyclic loading does not affect the bond strength of high strength concrete as long as the cyclic slip is less than the maximum slip for monotonic loading. The behavior of high strength concrete under a cyclic load is slightly different from that of normal strength concrete.Key words: bond, high strength, cyclic loading, bar spacing, loading rate, failure mechanism.

Finite Element Simulation on Behavior of the High-Strength Concrete Filled High-Strength Square Steel Tube Middle-Long Columns under Axial Compressive Load

2014 ◽  
Vol 578-579 ◽  
pp. 340-345
Author(s):  
Guo Chang Li ◽  
Bo Wen Zhu ◽  
Yu Liu
Keyword(s):  
Bearing Capacity ◽  
High Strength Concrete ◽  
Slenderness Ratio ◽  
High Strength ◽  
Steel Tube ◽  
New Combination ◽  
Length Variation ◽  
Compression Process ◽  
Strength Concrete ◽  
Square Steel Tube

In this paper, using ABAQUS, 16 high-strength concrete filled high-strength square steel tube middle-long columns’ axial compression process were simulated. The load-deflection relationships were obtained and the new combination in improving the bearing capacity and plastic deformation has a great advantage. Realization of length variation slenderness ratio by changing the length of column, this paper also study the influence of slenderness ratio, the main parameters of the high-strength concrete filled high-strength square steel tube middle-long column. It is found that both bearing capacity and the plastic capacity are associated with slenderness ratio.

scholarly journals Steel Plate Cold-Rolled Section Steel Embedded High-Strength Concrete Low-Rise Shear Wall Seismic Performance

2018 ◽  
Vol 2018 ◽  
pp. 1-18
Author(s):  
Min Gan ◽  
Yu Yu ◽  
Liren Li ◽  
Xisheng Lu
Keyword(s):  
Bearing Capacity ◽  
Failure Mode ◽  
Seismic Performance ◽  
High Strength Concrete ◽  
Steel Plate ◽  
Shear Walls ◽  
High Strength ◽  
Shear Wall ◽  
Steel Plates ◽  
Strength Concrete

Four test pieces with different steel plate center-to-center distances and reinforcement ratios are subjected to low-cycle repeat quasistatic loading to optimize properties as failure mode, hysteretic curve, skeleton curve, energy dissipation parameters, strength parameters, and seismic performance of high-strength concrete low-rise shear walls. The embedded steel plates are shown to effectively restrict wall crack propagation, enhance the overall steel ratio, and improve the failure mode of the wall while reducing the degree of brittle failure. Under the same conditions, increasing the spacing between the steel plates in the steel plate concrete shear wall can effectively preserve the horizontal bearing capacity of the shear wall under an ultimate load. The embedded steel plates perform better than concealed bracing in delaying stiffness degeneration in the low-rise shear walls, thus safeguarding their long-term bearing capacity. The results presented here may provide a workable basis for shear wall design optimization.

scholarly journals Reduce the Influence of Horizontal and Vertical Cold Joints on the Behavior of High Strength Concrete Beam Casting in Hot Weather by Using Sugar Molasses

2018 ◽  
Vol 7 (4.19) ◽  
pp. 794
Author(s):  
Fatimah Hameed Naser Al-Mamoori ◽  
Ali Hameed Naser Al-Mamoori
Keyword(s):  
High Strength Concrete ◽  
Concrete Beam ◽  
Setting Time ◽  
Weather Condition ◽  
High Strength ◽  
Point Load ◽  
Concrete Element ◽  
Strength Concrete ◽  
Hot Weather ◽  
The Impact

The current research studies the effect of cold joints on the behavior shear and flexure of High Strength Concrete (HSC) beams caused by delayed casting sequence during the hot weather in summer of Iraq.Fresh concrete should be kept alive during the various casting batches for concrete element by re-vibration. However, the over vibration caused loss in homogeneity and it is difficult to keep the workability of concrete during hot weather due to the effect of setting time.To deal with this problem of improper casting sequence, which eventually leads to the formation of cold joints, it will be used sugar waste (named as Sugar Molasses (SM)) is a by-product resulted from refining process of sugar as a delayed agent to increase the setting time in order to prevent early set of concrete due to adverse effects in construction joint of hot weather.In the current study, the first objective aims to investigate some of fresh and hardened mechanical properties of HSC (with high cement content) using SM at percentages of (0, 0.05, 0.1, 0.2, 0.3) % from the weight of cement under the concept of sustainable development. The second objective aims to investigate the location and surface texture effect of horizontal and vertical cold joints on the flexural and shear behavior of beam with/without SM. This objective includes testing of twenty four plain concrete beam of (110×110×650 mm) under two point load; half of them casting without roughing (smooth) the old layer and the other casted after roughed it.SM content of 0.2% of cement weight can improve compressive strength by about 11.2% at 28 days and delay initial setting time by about 4.617 hours (277 minutes). No adverse effect on concrete have been observed at this dosage of SM concentration for the ages of concrete cylinders studied. Delays in the setting of concrete at this dosage of SM content help in reducing the early setting of concrete and therefore reduced the impact of the cold joints formation in concrete beams under Iraqi hot weather condition. The failure load for the beams with SM of smooth and rough vertical joints is in the range between (1.95 - 2.12) and (1.46-1.37); respectively times that of the case of beam without SM. 

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