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 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.

scholarly journals Tests on sea sand concrete-filled stainless steel tubular stub columns

2018 ◽  
Author(s):  
Feiyu Liao ◽  
Chao Hou ◽  
W. J. Zhang ◽  
J. Ren
Keyword(s):  
Stainless Steel ◽  
Concrete Strength ◽  
High Strength ◽  
Normal Concrete ◽  
River Sand ◽  
Concrete Core ◽  
Cross Sectional ◽  
Composite Columns ◽  
Sea Sand ◽  
Stub Columns

This paper presents a series of tests on sea sand concrete-filled stainless steel tubular (SSCFST) stub columns under axial compression, where the main test parameters include type of fine aggregates (river sand, desalted sea sand and sea sand), steel ratio, and concrete strength. The failure mode, axial load versus axial shorten response, cross-sectional strength of the SSCFST specimens are investigated and compared with those of traditional composite columns with normal concrete. The confinement effect between stainless tube and the sea sand concrete is also evaluated. High strength and good ductility was observed for the tested SSCFST stub columns. In general, when being used as the concrete core in a composite column, differences of confinement behaviour between sea sand concrete and normal concrete are not significant, indicating the potential adoption of SSCFST columns in practice.

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.

Load-Bearing Capacity of Direct Inlay-Retained Fibre-reinforced Composite Fixed Partial Dentures with Different Cross-Sectional Pontic Design

2017 ◽  
Vol 68 (1) ◽  
pp. 94-100
Author(s):  
Oana Tanculescu ◽  
Adrian Doloca ◽  
Raluca Maria Vieriu ◽  
Florentina Mocanu ◽  
Gabriela Ifteni ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Fracture Pattern ◽  
Load Bearing Capacity ◽  
Cross Sectional ◽  
Load Bearing ◽  
Reinforced Composite ◽  
Polyethylene Fibre

The load-bearing capacity and fracture pattern of direct inlay-retained FRC FDPs with two different cross-sectional designs of the ponticwere tested. The aim of the study was to evaluate a new fibre disposition. Two types of composites, Filtek Bulk Fill Posterior Restorative and Filtek Z250 (3M/ESPE, St. Paul, MN, USA), and one braided polyethylene fibre, Construct (Kerr, USA) were used. The results of the study suggested that the new tested disposition of the fibres prevented in some extend the delamination of the composite on buccal and facial sides of the pontic and increased the load-bearing capacity of the bridges.

scholarly journals Comparative Study of CFRP-Confined CFST Stub Columns under Axial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Ying Guo ◽  
Yufen Zhang
Keyword(s):  
Comparative Study ◽  
Bearing Capacity ◽  
Limit Equilibrium ◽  
Concrete Strength ◽  
Confinement Effect ◽  
Unified Theory ◽  
Enhancement Ratio ◽  
Composite Columns ◽  
Cfst Columns ◽  
Stub Columns

This paper presented a comparative study of concrete-filled steel tubular (CFST) stub columns with three different confinement types from carbon fiber reinforced polymer (CFRP): outer circular CFRP, inner circular CFRP, and outer square CFRP. The compressive mechanism and physical properties of the composite column were analyzed firstly aiming at investigating the confinement effect of CFRP. Ultimate axial bearing capacity of these three CFRP-confined CFST columns was calculated based on Unified Theory of CFST and elastoplastic limit equilibrium theory, respectively. Meanwhile, the corresponding tests are adopted to validate the feasibility of the two calculation models. Through data analysis, the study confirmed the ultimate strength calculation results of the limit equilibrium method were found to be more reliable and approximate to the test results than those of Unified Theory of CFST. Then axial bearing capacity of the pure CFST column was predicted to evaluate the bearing capacity enhancement ratio of the three types of composite columns. It was demonstrated that the averaged enhancement ratio is 16.4 percent, showing that CFRP-confined CFST columns had a broad engineering applicability. Through a comparative analysis, this study also confirmed that outer circular CFRP had the best confinement effect and outer square CFRP did better than inner circular CFRP. The confinement effect of CFRP increased with the decrease of concrete strength, and it was proportional with relative proportions of CFRP and steel under the same concrete strength.

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 failure mechanism and end construction influences of double rectangular tube assembled buckling-restrained brace

2016 ◽  
Vol 20 (10) ◽  
pp. 1572-1585 ◽  
Author(s):  
Zi-qin Jiang ◽  
Yan-lin Guo ◽  
Ai-Lin Zhang ◽  
Chao Dou ◽  
Cai-Xia Zhang
Keyword(s):  
Bearing Capacity ◽  
Rational Design ◽  
Failure Modes ◽  
High Strength ◽  
Design Parameters ◽  
Local Pressure ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Buckling Restrained Brace ◽  
Rectangular Tube

The double rectangular tube assembled buckling-restrained brace is a new type of buckling energy consumption buckling-restrained brace. Because of its external restraining members, which are bound by high-strength bolts, its mechanical mechanism is more complicated and its failure modes are more varied. In this study, the double rectangular tube assembled buckling-restrained brace composition and three types of end constructions are introduced in detail. The influences of different design parameters on the performance of double rectangular tube assembled buckling-restrained brace are studied by numerical analysis methods; the possible failure modes and the influence of the end strengthening construction of double rectangular tube assembled buckling-restrained brace are also investigated, and a number of suggestions are proposed to improve this design. This study shows that the pinned double rectangular tube assembled buckling-restrained brace has four types of typical failure modes, namely, overall buckling failure, external end local pressure-bearing failure, bending failure of the extended strengthened core region and bolt threading failure. Rational design can prevent a buckling-restrained brace from losing its load-bearing capacity. In addition, compared with the end strengthening scheme with an external hoop, the end strengthening scheme with a strengthened bench can improve the load-bearing capacity of the double rectangular tube assembled buckling-restrained brace more effectively, and a reasonable design can also save materials.

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