Applications of Fire Engineering

Proceedings of the International Conference of Applications of Structural Fire Engineering (ASFE 2017), September 7-8, 2017, Manchester, United Kingdom

Martin Gillie, Yong Wang, Martin Gillie, Yong Wang

• Publisher: CRC Press
• Year: 2017
• Print ISBN:
  9781138092914
• eBook ISBN:
  9781351606394
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

This book holds the proceedings of the Conference on Applications of Structural Fire Engineering (ASFE 2017), held on September 7-8, 2017, in Manchester, UK. The ASFE'17 conference will be the next in a series (2009, 2011, 2013, 2015) of successful conferences that aim to bring together experts and specialists in design against fire from all over the world to share ideas and to acquire knowledge in the field of structural fire engineering. Practice in structural engineering increasingly accepts the benefits of performancebased approaches to the design of structures for fire resistance. This conference will focus on the application of design methods, both manual and computational, for structures to resist fire. Particularly relevant themes will be fire modelling, simulation of the heat transfer between fire and structures, and modelling of structural behaviour at elevated temperatures using numerical methods or software implementations of design codes.

Behaviors of axially restrained tubular members under fire—part 1: A novel test set-up

Fei Cheng, Yong Du & Yongzhen Zhang

College of Civil Engineering, Nanjing Tech University, Nanjing, Jiangsu, China

ABSTRACT: Tubular members with intermediate to high slenderness ratios are normally used in space frame structures. When the space frame structure is subjected to localized fire, only part of the structure is subjected to heating and the heated members are restrained by the adjacent members which are not heated. In this study, a novel experimental set-up has been proposed to test an end restrained axially loaded member subjected to fire. In the experiment, the axial end restraint is simulated by a series of pre-compressed springs. These pre-compressed springs can provide a constant axial end restraint stiffness during the fire test. When subjected to heating, the member tends to expand due to thermal effect, but it is restrained by the axial springs which provide a constant end-restraint stiffness through the entire heating process. This novel test set-up can simulate the actual behavior of compression chord member in a space frame structure when subjected to localized fire. The axial end restraint stiffness can be adjusted by changing the number of springs or by using springs with different stiffness. This paper describes the novel test set-up and the test load deflection curve of the heated member before and after buckling. The second part of the companion paper presents the test results including parameter studies investigating the important factors such as end restraint stiffness, member slenderness ratio, load ratio and initial imperfection on the fire resistance of axially compressed members.

Keywords: Axially restrained member; Fire test; Restraint set-up; spring

1 INTRODUCTION

As the interaction behaviors among members exposed to natural fires due to global structural succession properties, there are different mechanical behaviors between isolate members and that in global structures (Wang. 1994 & 2004, Franssen. 2000, Tan. 2007, Peijun Wang 2008). It is worth noting that the restrained behaviors among structural members induce more complex response for spatial grid steel structure exposed to localised fire (Du. 2014). In order to capture the mechanical response of restrained members at elevated temperature correctly, a series of fire tests have been conducted to investigate the mechanical response of restrained steel columns, beams in fires. There are various equipments developed to provide axially restraint to study the influence factors of mechanical behaviors for restrained members in fire. In 1998, a fire test of the restrained steel column with 1.8 m length had been conducted by Ali et al., in which two H-section steel beams parallel located at one end of the column to provide powerful axial restraint. Rodrigues et al. employed an H-section steel beam to provide the restraint for a steel bar with 460 mm length, and firstly studied the behaviors of restrained members at post-buckling stage in fire test. Then, Rodrigues et al. conducted another fire test of full scale restrained reinforce concrete column with 3 m height. In this test, two cross H-section steel beams located at one end of column to provide restraint and the different restraint stiffness had been provided by changing the length of two H-section steel beams. Tan et al. conducted a series of fire test of restrained H-section steel columns with 1.74 m height, in which an H-section steel beam provided restraint at one end of column. In 2012, Qu et al. conducted a fire test of restrained steel tubes with 1.96 m length, in which H-section steel beam was replaced by an elastic steel plate to get large elastic deformation.

H-section steel beams have been widely employed to provide restraint for restrained specimens in fire test. However, H-section steel beams cannot provide elastic deformation large enough for restrained specimens from pre-buckling to post-buckling stage. A mechanical model of a restrained member in fire is shown in Figure 1. The elastic deformation at the mid-span of a steel beam provides the restraint stiffness for restrained specimen shown in Figure 2, and the maximum elastic deformation can be obtained by Eq. (1) as below.

${\omega }_{\max }=\frac{l^2{f}_{\text{y}}}{12E{y}_{\max }}$

(1)

Shown in Figure 3, the maximum elastic deformation of the H-section beam with 3 m span, size of section H150 × 80 × 6 × 8, Young’s modulus, E = 2.05 × 10⁵ N/mm² and yield strength, f_y = 235 N/mm², has been obtained as 16.7 mm.

In 2014, J. Zhou et al. presented a case study and determined that a restrained chord with 3 m length; size of cross section, A = 4825 mm²; diameter, d = 200 mm; thickness, t = 8 mm; yield strength, f_y = 235 N/mm² restrained by the H-section steel beam had vertical displacement of 20.5 mm at 355°C. So the plastic deformation occurred in the mid-span of the H-section beam due to vertical displacement at one end of restrained specimen in fire can change the restraint stiffness of restrained specimens.

According to Eq. (1), the elastic deformation of H-section beam can be efficiently increased by the increased length or decreased size of cross section. However, larger test space must be provided for larger length of H-section steel beams, and smaller size of H-section steel beams cannot provide restrained stiffness strong enough for specimen. Thus, in this study, a novel restraint set-up was developed to provide elastic deformation large enough for axial restrained specimen fire test.

Figure 1. Mechanical model of restrained member.

Figure 2. Fire test model of restrained member.

Figure 3. Mechanic model of H-section steel beam.

2 ELASTIC DISPLACEMENT OF RESTRAINT SET-UP

As restraint springs can only operate effectively under compression state, a pre-compressed displacement of springs, Δ₁, should be imposed by pus...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Sensitivity of resistance of cold-formed steel tubular columns to elevated temperature mechanical properties
• Fire performance of CFRP strengthened cold-formed steel tubular columns
• Sensitivity of elevated temperature load carrying capacity of thin-walled steel members to local imperfections
• High-temperature properties of aluminum alloy EN6082AW T6
• A manual calculation method for the check of the fire resistance of concrete columns subjected to a standard fire
• Fire design of continuous concrete filled steel tubular column for a multi-storey building
• Performance-based fire design of a 14-story residential mass timber building
• Influence of heating rate and thermal incompatibilities on the test results of concrete cylinder specimens with polypropylene fibres under heating
• To fire resistance of the steel and fibre-reinforced concrete circular hollow section column
• Fire resistance of axially restrained and partially unprotected Ultra Shallow Floor Beams (USFB®) and DELTABEAM® composite beams
• Behaviors of axially restrained tubular members under fire—part 1: A novel test set-up
• Behaviors of axially restrained tubular members under fire—part 2: Experimental study
• Robustness index for steel portal frames against fire-induced progressive collapse
• Fire safety of high-rise residential buildings: Scope of fire engineering and comparison between UK and Turkish practice
• Comparative fire analysis of steel-concrete composite buildings designed following performance-based and US prescriptive approaches
• Fire resistance of reinforced concrete columns: A systematic review
• Reviewing the veracity of a zone-model-based-approach for the assessment of enclosures formed of exposed CLT
• Numerical investigation of intumescent ‘coatback’ on unprotected secondary beams
• Numerical simulation of fire-resistance test
• Meta-analysis of UK, USA and New Zealand fire statistics databases with respect to damage and financial loss
• Effect of upgrading concrete strength class on fire performance of reinforced concrete columns
• A 2D beam element for the analysis of flexural buckling of steel structures at elevated temperatures
• Improving fire resistance of existing concrete slabs by concrete topping
• The effect of vertically travelling fires on a multi-storey steel frame building
• A method for hybrid fire testing: Development, implementation and numerical application
• Computational study of the 2D thermal response of high-strength structural steel cables under various heating regimes
• Numerical studies on headed shear studs under elevated temperatures
• The influence of slab ductility on the robustness of composite joints in fire
• Fire safety research towards enabling timber structures in Canada
• Optimum investment in structural fire safety: Case-study on the applicability of deflection-based failure criteria
• Finite element analysis of axial forces in composite beams under fire
• Structural fire behaviour and testing of protected and unprotected steel-concrete composite cellular beams
• An out-of-plane mechanical response of a planar steel frame in fire
• Influence of creep on buckling of steel columns in fire conditions
• Effect of the thermal input on the behavior of intumescent coatings
• Shear buckling resistance of steel plate girders at normal and elevated temperatures
• A cross-section deformable beam finite element model for fire simulations of thin-walled steel columns
• Verification of 2D heat transfer models developed in LS-DYNA for structural fire engineering applications
• Fire engineering design of composite floor systems for two way response in severe fires
• Effects of heat-treatment methods on mechanical performance of high-tensile strength steel subject to elevated temperatures
• Post-earthquake fire behaviour of composite steel-framed structures
• Compressive stress-strain relationship of strain-hardening cementitious composite with hybrid fibres after high temperature exposure
• Author index