Search results
1 – 10 of 803Richard Walls, Celeste Viljoen, Hennie de Clercq and Charles Clifton
This paper aims to present a reliability analysis of the slab panel method (SPM) for the design of composite steel floors in severe fires. Rather than seeking to accurately define…
Abstract
Purpose
This paper aims to present a reliability analysis of the slab panel method (SPM) for the design of composite steel floors in severe fires. Rather than seeking to accurately define failure levels, this paper highlights areas of uncertainty in design and their effect on design results, whilst providing approximate reliability levels.
Design/methodology/approach
A Monte Carlo simulation has been conducted using the SPM design procedure to produce probability density functions of floor capacity for various floor layouts. Statistical input variables were obtained from the literature. Different configurations, geometries and fire severities are included to demonstrate how predicted floor capacities are influenced.
Findings
From the research presented, it is clear that the predicted reliability of SPM systems varies relative to a large number of criteria, but especially parameters related to fire loading. Predicted capacities are shown to be conservative compared to results of furnace and large-scale natural fire tests, which exhibit higher fire resistance. Due to distinct fire hazard categories with associated input values, there are step discontinuities in capacity graphs.
Originality/value
Limited research has been done to date on the reliability of structures in fire as discussed in this paper. It is important to verify the reliability levels of systems to ensure that partial and global factors of safety are adequate. Monte Carlo simulations are shown to be effective for calculating the average floor capacities and associated standard deviations. The presentation of probability density functions for composite floors in severe fires is novel.
Details
Keywords
Li Zhang, Ya Wei, Francis Tat Kwong Au and Jing Li
This study aims to investigate the influence of tendon layout, pre-stressing force, bond condition and concrete spalling on the structural behaviour of two-way post-tensioned flat…
Abstract
Purpose
This study aims to investigate the influence of tendon layout, pre-stressing force, bond condition and concrete spalling on the structural behaviour of two-way post-tensioned flat slabs at elevated temperatures.
Design/methodology/approach
Fire tests of four scale specimens of two-way post-tensioned concrete flat slabs were performed and analysed. Three of them were provided with bonded tendons, while the other was unbonded for comparison. The fabrication of specimens, phenomena observed during testing, temperature distributions, deflections and occurrence of concrete spalling were examined.
Findings
Different degrees of concrete spalling observed at the soffit had significant effects on the temperature distribution and stress redistribution. This was the major reason for the progressive concrete spalling observed, resulting in loss of structural integrity and stiffness.
Originality/value
The structural behaviour of two-way post-tensioned concrete flat slabs at elevated temperatures is less understood compared to their one-way counterparts. Therefore, the present study has focused on the structural behaviour of two-way post-tensioned concrete flat slabs with bonded tendons in fire, a field in which relatively little information on experimental work can be found.
Details
Keywords
Jason Martinez and Ann Jeffers
A methodology for producing an elevated-temperature tension stiffening model is presented.
Abstract
Purpose
A methodology for producing an elevated-temperature tension stiffening model is presented.
Design/methodology/approach
The energy-based stress–strain model of plain concrete developed by Bažant and Oh (1983) was extended to the elevated-temperature domain by developing an analytical formulation for the temperature-dependence of the fracture energy Gf. Then, an elevated-temperature tension stiffening model was developed based on the modification of the proposed elevated-temperature tension softening model.
Findings
The proposed tension stiffening model can be used to predict the response of composite floor slabs exposed to fire with great accuracy, provided that the global parameters TS and Kres are adequately calibrated against global structural response data.
Originality/value
In a finite element analysis of reinforced concrete, a tension stiffening model is required as input for concrete to account for actions such as bond slip and tension stiffening. However, an elevated-temperature tension stiffening model does not exist in the research literature. An approach for developing an elevated-temperature tension stiffening model is presented.
Details
Keywords
The rapidly developing technology in the construction industry in recent years has produced a specialised industry concerned with the design, manufacture and subsequent use of…
Abstract
The rapidly developing technology in the construction industry in recent years has produced a specialised industry concerned with the design, manufacture and subsequent use of cladding fixings.
Caroline Silva Araújo, Emerson de Andrade Marques Ferreira and Dayana Bastos Costa
Tracking physical resources at the construction site can generate information to support effective decision-making and building production control. However, the methods for…
Abstract
Purpose
Tracking physical resources at the construction site can generate information to support effective decision-making and building production control. However, the methods for conventional tracking usually offer low reliability. This study aims to propose the integrated Smart Twins 4.0 to track and manage metallic formworks used in cast-in-place concrete wall systems using internet of things (IoT) (operationalized by radio frequency identification [RFID]) and building information modeling (BIM), focusing on increasing quality and productivity.
Design/methodology/approach
Design science research is the research approach, including an exploratory study to map the constructive system, the integrated system development, an on-site pilot implementation in a residential project and a performance evaluation based on acquired data and the perception of the project’s production team.
Findings
In all rounds of requests, Smart Twins 4.0 registered and presented the status from the formworks and the work progress of buildings in complete correspondence with the physical progress providing information to support decision-making during operation. Moreover, analyses of the system infrastructure and implementation details can drive researchers regarding future IoT and BIM implementation in real construction sites.
Originality/value
The primary contribution is the system proposal, centralized into a mobile app that contains a Web-based virtual model to receive data in real time during construction phases and solve a real problem. The paper describes Smart Twins 4.0 development and its requirements for tracking physical resources considering theoretical and practical previous research regarding RFID, IoT and BIM.
Details
Keywords
Wee Toh and Nick Bernabè
This paper presents a comparison, based on real practical case studies, between the simple analytical BRE-Bailey method (BRE-BM) and the advanced finite element model (FEM) Vulcan…
Abstract
This paper presents a comparison, based on real practical case studies, between the simple analytical BRE-Bailey method (BRE-BM) and the advanced finite element model (FEM) Vulcan for the membrane action of composite slab panels with unprotected secondary beams at elevated temperatures. Both approaches predicted the membrane behaviour of the composite slabs, comprising compressive membrane action around the slabs' perimeter and tensile membrane action in the central span region of the slabs. This paper mainly studies the effects of the orientation of unprotected secondary beams and the boundary conditions on tensile membrane action of composite slab panels. The results show that the application of the BRE-BM is generally restricted by the conservative assumption of the maximum allowable vertical displacement. In contrast, the FEM estimates higher load-carrying capacities as well as providing a full displacement-time relationship throughout the heating of the slabs. For slab panels with unprotected secondary beams with an orientation in the short span, tensile membrane action can be easily mobilised without increasing fire protection to the boundary supporting beams. However, the FEM predictions on the slab capacities and deflections in fire are very sensitive to the continuity of the reinforcement over the protected boundary beams.
Khadejah Alameen Abouleiwun, Hazem M.F. Elbakry, Muhammad Ahmed Diab and S.F. El-Fitiany
In this study, the behavior of a multi-story flat plate structure during fire exposure is investigated using numerical simulations conducted with using ABAQUS software.
Abstract
Purpose
In this study, the behavior of a multi-story flat plate structure during fire exposure is investigated using numerical simulations conducted with using ABAQUS software.
Design/methodology/approach
A three-dimensional finite element model is then carried out on the RC flat slab structure exposed to standard ISO-834 fire at different location arrangements. The model examines mid-span deflection, shear demand on the columns, bending moment and the membrane action of the floor slab.
Findings
The latter plays a main role to increase the capability and ductility of the slab at longer fire exposure to compensate the reduction in the flexural capacity. Also, shear demand in columns becomes bigger in cases of more than one surrounding slab exposed to fire at the same time.
Originality/value
This work focuses on the influence of the horizontal force on columns due to thermal expansion of slab which should be taken into account in the design of multistory multi-bay building considering it the same as the resulted horizontal force from the wind and seismic effect, the traveling fire and the restraint effect.
Ya Wei, Francis T.K. Au, Jing Li and Neil C.M. Tsang
This paper aims to understand the structural fire performance of two-way post-tensioned flat slabs, particularly their deformations and load-carrying mechanisms in fire, and to…
Abstract
Purpose
This paper aims to understand the structural fire performance of two-way post-tensioned flat slabs, particularly their deformations and load-carrying mechanisms in fire, and to explore the behaviour of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons in fire.
Design/methodology/approach
Four tests of post-tensioned high-strength self-compacting concrete flat slabs were conducted under fire conditions. Numerical modelling using the commercial package ABAQUS was conducted to help interpret the test results.
Findings
Two of the specimens with lower moisture contents demonstrated excellent fire resistance performance, while the others with slightly higher moisture contents experienced severe concrete spalling.
Originality/value
The test results were discussed in respect of thermal profiles, deflections, crack patterns and concrete spalling. The performance of post-tensioned high-strength self-compacting concrete flat slabs with unbonded tendons under fire conditions was better understood.
Details
Keywords
Anthony Abu, Verotiana Ramanitrarivo and Ian Burgess
A simple folding mechanism, which considers the contributions of internal unprotected beams and protected edge beams, has been proposed for isolated slab panels in fire…
Abstract
A simple folding mechanism, which considers the contributions of internal unprotected beams and protected edge beams, has been proposed for isolated slab panels in fire conditions. The current study extends the mechanism to include the reinforcement in the slab as well as continuity across the protected edge beams. Structural failure of the panel depends on the applied loads, the relative beam sizes, their locations within the building, their arrangement in the slab panel, the panel's location and the severity of fire exposure. These factors are considered in the development of a number of collapse mechanisms for verification so they may eventually serve as an additional check within the Bailey-BRE design method, to make it more robust for routine design of composite floors in fire. Comparisons are made with the finite element software Vulcan and other design acceptance criteria.
Details
Keywords
Nor Salwani Hashim, Fatimah De’nan and Nurfarhah Naaim
Nowadays, residential buildings have become increasingly important due to the growing communities. The purpose of this study is to investigate the behavior of a steel structural…
Abstract
Purpose
Nowadays, residential buildings have become increasingly important due to the growing communities. The purpose of this study is to investigate the behavior of a steel structural framing system that incorporates lightweight load-bearing walls and slabs, and to compare the weight of materials used in cold-formed and hot-finished steel structural systems for affordable housing.
Design/methodology/approach
Four types of models consisting of 243 members were simulated. Model 1 is a cold-formed steel structural framing system, while Model 2 is a hot-finished steel structural framing system. Both Models 1 and 2 use lightweight wall panels and lightweight composite slabs. Models 3 and 4 are made with brick walls and precast reinforced concrete systems, respectively. These structures use different wall and slab materials, namely, brick walls and precast reinforced concrete. The analysis includes bending behavior, buckling resistance, shear resistance and torsional rotation analysis.
Findings
This study found that using thinner steel sections can increase the deflection value. Meanwhile, increasing member length and the ratio of slenderness will decrease buckling resistance. As the applied load increases, buckling deformation also increases. Furthermore, decreasing shear area causes a reduction in shear resistance. Thicker sections and the use of lightweight materials can decrease the torsional rotation value.
Originality/value
The weight comparison of the steel structures shows that Model 1, which is a cold-formed steel structure with lightweight wall panels and lightweight composite slabs, is the most suitable model due to its lightweight and affordability for housing. This model can also be used as a reference for the optimal design of modular structural framing using cold-formed steel materials in the field of civil engineering and as a promotional tool.
Details