scholarly journals Structural fire performance of restrained composite columns made of concrete-filled square and circular hollow sections

Fire Research ◽  
2016 ◽  
Author(s):  
João Paulo C. Rodrigues ◽  
Luís Laím ◽  
Helder D. Craveiro
Keyword(s):  
Fire Resistance ◽  
Failure Modes ◽  
Local Buckling ◽  
Critical Time ◽  
Load Level ◽  
Steel Frame ◽  
Hollow Section ◽  
Standard Fire ◽  
Buckling Behavior ◽  
Rotational Restraint

Most of the previous studies on concretefilled steel hollow section columns at high temperatures addressed the effect of depth-tothickness ratio, column slenderness, initial applied load level, load eccentricity, and local buckling of concrete-filled steel tubes on the fire resistance of these columns. For this reason, it important and required to study the influence of the axial and rotational restraint on the buckling behavior of these types of columns subjected to fire. The results of a series of fire resistance tests on these types of columns inserted in a steel frame are presented and discussed in this paper. The primary test parameters taken into account were column slenderness, type of section geometry, and axial and rotational restraint level imposed by a surrounding steel frame to the columns. The specimens were then uniformly exposed to the ISO 834 standard fire curve, and the critical time (fire resistance), failure temperature distribution and respective failure modes were assessed. Finally, the results of this research study showed most of all that the fire resistance of identical semi-rigid ended columns may be not significantly affected by the stiffness of the surrounding structure but, on the contrary, their post-buckling behavior may be affected.

EXPERIMENTAL STUDY ON STRUCTURAL BEHAVIOR OF FIRE PROTECTED DOUBLE CFT COLUMN SUBJECTED TO FIRE LOAD

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Kyung Soo Chung ◽  
Jae Sung Lee ◽  
Jong Eun Song ◽  
Woo Chul Kim ◽  
Heung Youl Kim ◽  
...  
Keyword(s):  
Fire Resistance ◽  
Fire Test ◽  
Failure Modes ◽  
Temperature Deformation ◽  
Fire Tests ◽  
Fire Performance ◽  
Fire Load ◽  
Standard Fire ◽  
Fire Endurance ◽  
Cft Column

New concrete filled double-tube (CFDT) sections consist of an inner and outer tube with fire protection mortar (FPM) filling the cavity between them and the inner tube also filled with concrete or not. An investigation into the fire performance of CFDT during the standard fire test is reported. Six full size FPM filled CFDT columns were designed for the fire tests. Detail failure modes of overall specimens and each component in the columns as well as temperature, deformation and fire endurance were presented. It showed that the fire resistance in the CFDT columns is significantly higher than that in concrete filled steel tubular (CFT) columns. Investigation into the fire performance of the columns reveals possible solutions to improve the fire resistance of CFT members.

scholarly journals EXPERIMENTAL STUDY ON BEHAVIOR OF UNPROTECTED FOAMED CONCRETE FILLED STEEL HOLLOW COLUMN UNDER FIRE

2021 ◽  
Vol 12 (2) ◽  
pp. 189-202
Author(s):  
Bishir Kado ◽  
Shahrin Mohammad ◽  
Yeong Huei Lee ◽  
Poi Ngian Shek ◽  
Mariyana Aida Ab Kadir
Keyword(s):  
Fire Resistance ◽  
Applied Load ◽  
Fire Test ◽  
Lightweight Concrete ◽  
Steel Tube ◽  
Load Level ◽  
Exposure Test ◽  
Hollow Section ◽  
High Rise ◽  
Foamed Concrete

Reduction in self-weight and achievement of full fire resistance requirements are some of the important considerations in the design of high-rise structures. Lightweight concrete filled steel tube (CFST) column provides an alternative method to serve these purposes. Recent studies on lightweight CFST columns at ambient temperature have revealed that foamed concrete can be a beneficial and innovative alternative material. Hence, this study investigates the potential of using foamed concrete in circular hollow steel columns for improving fire resistance. A series of nine fire test on circular unfilled hollow and foamed concrete filled hollow section column were carried out. ISO 834 standard fire exposure test were carried out to investigate the structural response of these columns under fire. The main parameters considered are load level and foamed concrete density; foamed concrete density used are 1500 kg/m3 and 1800 kg/m3 at 15%, 20%, and 25% load level. All the columns tested are without any external fire protection, with concentrically applied load under fixed-fixed boundary conditions. The columns dimension was 2400 mm long, 139.7 mm diameter and steel tube thickness of 6 mm. The fire test result showed that foamed concrete increases the fire resistance of steel hollow column up to an additional 16 minutes. The improvement is more at load level above 15%, and the gain in fire resistance is about 71% when 1500 kg/m3 density foamed concrete is used. Generally, foamed concrete filled steel hollow column demonstrate a good structural fire behavior, based on the applied load and foamed concrete density. Also, inward local buckling was averted by filling the steel hollow column with foamed concrete. General method for composite column design in Eurocode 4 adopted to calculate the axial buckling load of 1500 kg/m3 foamed concrete filled columns.  These type of columns can be used for structures like airports, schools, and stadiums; taking the advantage of exposed steel for aesthetic purpose and high fire resistance. It can also be used for high rise structures; taking advantage of high fire resistance and reduction in self-weight of a structure.

scholarly journals About the use of semi-continuity in simply supported composite steel and concrete beams, to remove fireproof coatings for standard-fire resistance requirement of less than 30 minutes

2019 ◽  
Vol 12 (5) ◽  
pp. 1183-1204
Author(s):  
L. C. ROMAGNOLI ◽  
V. P. SILVA
Keyword(s):  
Fire Resistance ◽  
Concrete Beams ◽  
Local Buckling ◽  
Rotational Stiffness ◽  
Design Code ◽  
Simply Supported ◽  
Standard Fire ◽  
Equivalent Time ◽  
Lower Standard ◽  
Composite Steel

Abstract Previous studies of the behavior under fire conditions of composite steel and concrete beams, not subjected to local buckling (compact steel profile), showed that it’s not possible to justify, by design code methods, the absence of fire coating for 30 minutes standard-fire resistance requirement, even when considering the support rotational stiffness provided by the upper longitudinal slab reinforcement (semi-continuity). The purpose of this work is to verify the viability of this proposal for lower standard-fire resistance time, which, although rare, may occur with the use of the equivalent time method.

scholarly journals Behavior of partially encased composite members under various load conditions: Experimental and analytical models

2018 ◽  
Vol 22 (1) ◽  
pp. 94-111 ◽  
Author(s):  
Mehdi Ebadi Jamkhaneh ◽  
Mohammad Ali Kafi ◽  
Ali Kheyroddin
Keyword(s):  
Finite Element ◽  
Failure Modes ◽  
Numerical Models ◽  
Local Buckling ◽  
Marginal Effect ◽  
Composite Column ◽  
Buckling Behavior ◽  
Bending Load ◽  
Torsional Behavior ◽  
Load Conditions

This study addresses the experimental behavior of octagonal partially encased composite column under axial and bending load conditions. The complementary study on axial and combined axial–torsional behavior is done through finite element analysis. The main parameters for the experiment part are reinforcement details and failure modes. The six parameters of this analytical analysis include width-to-thickness ratio of flange, transverse links spacing and diameter, welding line arrangements, and different types of retrofit of cross-shaped steel (concrete encasement, use of stiffener plates and transverse links). To verify accuracy of the proposed three-dimensional finite element model, the axial behavior of the numerical models was compared with test specimens. Experimental results of the axial study show that concrete crushing phenomena and local buckling behavior occurred for all specimens under ultimate stage of loading. It should be noted that local buckling behavior occurred after crushing phenomena. The analysis of bending assessment demonstrated that the use of stirrups has no remarkable effect on increasing the effective bending moment strength of octagonal partially encased composite columns. Meanwhile, an equation was developed based on comprehensive parametric study of octagonal partially encased composite column using detailed finite element analyses. Under axial–torsional load conditions, one could conclude that steel shear plates should be placed at the end zones of column to heighten torsional resistance of member. Meanwhile, transverse links were found to exert marginal effect on torsional behavior of octagonal partially encased composite column.

Experimental Study on Fire Resistance Performance of Glulam Beams

2012 ◽  
Vol 193-194 ◽  
pp. 539-543
Author(s):  
Zhao Peng Ni ◽  
Pei Fang Qiu
Keyword(s):  
Fire Resistance ◽  
Failure Modes ◽  
Test Results ◽  
Fire Performance ◽  
Standard Fire ◽  
Resistance Performance ◽  
Fire Resistance Rating ◽  
Resistance Rating ◽  
Resistance Tests

Abstract : A series of standard fire-resistance tests were carried out to study the fire performance, failure modes and fire-resistance ratings of glulam beams. The test results showed that these glulam beams performed well during the tests, and the fire-resistance rating requirements can be achieved as expected. The study has provided necessary knowledge and experimental data for the determination of fire-resistance performance of glulam beams in the fire code of China.

LOCAL BUCKLING BEHAVIOR OF DOUBLE-COPED STEEL BEAMS

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Cheng Fang ◽  
Michael Yam ◽  
V. P. Iu ◽  
K. F. Chung
Keyword(s):  
Failure Modes ◽  
Pushover Analysis ◽  
Local Buckling ◽  
Design Approach ◽  
Steel Beams ◽  
Buckling Mode ◽  
Buckling Behavior ◽  
Buckling Resistance ◽  
Web Buckling ◽  
Irregular Bridges

Local web buckling is one of the most common failure modes for coped steel beams. While several studies have been undertaken focusing on the behavior of top-flange/single-coped beams, double-coped beams have received little attention. To fill this knowledge gap, this paper presents experimental and numerical studies on local web buckling behavior of double-coped steel beams. Five full-scale tests were conducted, and the main test parameters were cope length and cope depth. Local web buckling was observed as the main failure mode for all of the five specimens, and the buckling resistance was found to decrease with increasing cope length and cope depth. A FE study was subsequently conducted, where the response of the FE models agreed well with the test results, especially in terms of buckling mode and buckling resistance. The test and FE results were compared with those predicted by an existing design approach. The design results were found to be quite conservative, and hence further investigation may be required to achieve a more accurate design approach. procedure and faster computational efficiency than the Modal Pushover Analysis (MPA) procedure for irregular bridges.

scholarly journals Buckling Behavior of Non-Retrofitted and FRP-Retrofitted Steel CHS T-Joints

2021 ◽  
Vol 11 (7) ◽  
pp. 3098
Author(s):  
Amin Yazdi ◽  
Maria Rashidi ◽  
Mohammad Alembagheri ◽  
Bijan Samali
Keyword(s):  
Compressive Loading ◽  
Local Buckling ◽  
Buckling Mode ◽  
T Joints ◽  
Hollow Section ◽  
Frp Composite ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Post Buckling ◽  
Circular Hollow Section

This paper aims to investigate the buckling behavior of circular hollow section (CHS) T-joints in retrofitted and non-retrofitted states under axial brace compressive loading. For this purpose, two types of analysis are carried out. The first one is evaluating the critical buckling load in various tubular joints, and the other one is investigating the post-buckling behavior after each buckling mode. More than 180 CHS T-joints with various normalized geometric properties were numerically modeled in non-retrofitted state to compute their governing buckling mode, i.e., chord ovalization, brace local, or global buckling. Then three joints with different buckling modes were selected to be retrofitted by fiber-reinforced polymer (FRP) patches to illustrate the improving effect of the FRP wrapping on the post-buckling performance of the retrofitted joints. In addition, FRP composite failures were investigated. The results indicate that the FRP retrofitting is able to prevent the brace local buckling, and that matrix failure is the most common composite failure in the retrofitted joints.

Buckling Behavior of Circular Steel Tubes under Fire

2018 ◽  
Vol 763 ◽  
pp. 270-278
Author(s):  
Ji Hye Seo ◽  
Deok Hee Won ◽  
Woo Sun Park ◽  
Seung Jun Kim
Keyword(s):  
Fire Resistance ◽  
Local Buckling ◽  
Steel Structure ◽  
Steel Structures ◽  
Steel Tube ◽  
Elastic Buckling ◽  
Element Analysis ◽  
Steel Members ◽  
Buckling Behavior ◽  
Circular Steel Tube

Recently, several lives were lost because of the collapse of structures under fire. Steel members are mainly used in the columns and beams of buildings for improving construction efficiency. The fire resistance of steel structure is very important because when it don’t have fire resistive covering, it rapidly changes with high temperature. In fire resistance design of steel, steel structure must have fire resistive covering. But many facilities as temporary facilities, parking lot don’t have it. The buckling behavior of steel structures under fire is also significant because it can cause local buckling failure through the reduction in structural material properties by temperature. In this study, the elastic buckling behavior of a circular steel tube under fire was investigated using finite element analysis. The parameters for this analysis used were, diameter–thickness ratio, fire exposure area, and fire scenarios. The elastic buckling strength of circular steel tube rapidly decreased when subjected to the fire curve. Local buckling occurred and this can lead to global failure. When fire resistance design of circular steel tube was performed, buckling behavior must be considered.

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