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  • 1.
    Cheng, Xudong
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Byström, Alexandra
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Iqbal, Naveed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Prediction of temperature variation in an experimental building2011In: Proceedings of International Conference Applications of Structural Fire Engineering: Prague, 29 April 2011, 2011, p. 387-392Conference paper (Refereed)
  • 2.
    Iqbal, Naveed
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Fodor, Jovan
    Czech Technical University, Prague.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Veljkovic, Milan
    Delft University of Technology.
    Catenary action in single storey industrial halls subjected to localized fires2017In: Proceedings of the 7th International Conference on Mechanics and Materials in Design (M2D) / [ed] Gomes, JFS; Meguid, SA, Porto: INEGI-FEUP , 2017, p. 1627-1628Conference paper (Refereed)
    Abstract [en]

    This paper reports on the results from extensive finite element study of single storey industrial halls subjected to the action of localized fires. The results show offer structural resistance in fire situations that are much higher than would be expected from a prescriptive approach. It has been shown that actual resistance of these structural members in fire situations can exceed their primary resistance mechanism through flexural action only. Alternative load transfer mechanism through catenary action offers the added resistance at much higher temperatures than the conventional critical temperatures from prescriptive design. The paper also presents simplified calculation procedures that can be used to reasonably predict the structural resistance at elevated temperatures considering the catenary action

  • 3.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Alternativ metod för värdering av personrisk i hallbyggnader vid brand2019Other (Other (popular science, discussion, etc.))
  • 4. Sandström, Joakim
    Life safety in single-story steel frame buildings, Part II - probabilistic designIn: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325Article in journal (Refereed)
    Abstract [en]

    Including consideration to the fire conditions in structural fire safety design enables a nuanced evaluation of the life safety objective in single-story-, single-compartment buildings. This paper investigates the probability of unacceptable consequences from structural fire damage in a typical Scandinavian single-story steel frame building and discusses it in relation to life safety. The investigated building does not meet the safety levels as stipulated by EN 1990 for structural fire damage. However, by including consideration to the fire conditions in the compartment, it is shown that the life safety objective is not compromised by the structural fire damage, i.e. the structure remains intact as long as any individuals/firefighters can survive within the fire area compartment.

    This paper is a complement to the paper Life safety in single-story steel frame buildings, Part I – deterministic design by Sandström (2019) considering the same design philosophy but with a deterministic design approach.

  • 5. Sandström, Joakim
    Life safety in single-story steel frame builidngs, Part I - deterministic design2019In: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325Article in journal (Refereed)
    Abstract [en]

    This paper discusses fire safety design of single story-, single compartment buildings and evaluates whether time to structural damage is a relevant criterion when lethal fire conditions develop long before any structural fire damage can occur. Current performance-based design practice aims at achieving the life safety objective by preventing structural failure for the entire duration of a natural fire or for a fixed time of standard fire exposure. Prevention of structural fire damage is always relevant for multistory buildings, or buildings with complex geometries as structural fire damage may then threaten occupants and/or firefighters outside the area directly affected by the fire. However, for single-story-, single-compartment buildings, prevention of structural fire damage is less relevant in relation to the life safety objective.

    The advantage of the new design philosophy presented in this paper is the possibility to define how the level of structural fire resistance in single-story-, single-compartment buildings can be determined in a consistent way. This level of fire resistance requirement in these buildings differ amongst countries but could be harmonized by accepting of the design philosophy suggested in this paper.

    The proposed approach is demonstrated in a design case study of a steel truss in a typical Swedish single-story steel frame building. While not complying with deemed to satisfy fire resistance ratings, it is argued that the proposed design still can fulfill the life safety objective.

  • 6.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    The life safety objective in structural fire safety design2019Doctoral thesis, comprehensive summary (Other academic)
  • 7.
    Sandström, Joakim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Thermal boundary conditions based on field modeling of fires: Heat transfer calculations in CFD and FE models with special regards to fire exposure represented with adiabatic surface temperatures2013Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Combining computer fluid dynamic, CFD, models with finite element, FE, models to calculate temperature in fire exposed structures can reduce design temperatures in structures while still obtaining the level of structural fire safety stipulated by society. A better understanding of heat transfer and the concept of adiabatic surface temperatures, AST, the transition of data between models can be simplified and more accurate temperature predictions can be made.The thesis focuses on heat transfer calculations by employing AST in particular, and how this can be used as a means of coupling any CFD and FE-analysis code. The thesis presents a method for performing FE-analysis of the thermal response with input data calculated with the computer code FDS, Fire Dynamics Simulator. Parallel to this, the heat balance equation in FDS is tested and an alternate numerical algorithm is developed and tested.Firstly, a verification model is developed to test the radiative and convective part of the existing heat balance equation in FDS. An alternate numerical algorithm for calculation of the heat transfer at surfaces is developed as a more homogenous alternative for CFD codes.Secondly is a study on how to extract AST from an arbitrary point with direction in a CFD calculation using an infinitesimal surface. Instead of modeling numerous small surfaces for extracting AST, a post processor is developed to calculate AST independent of any modeled surface. For CFD codes, such as FDS that depend on a rectilinear grid, this enables calculation of AST in any direction, not only directions normal to the Cartesian planes.Finally, a comparison is made between different methods for calculating temperatures in steel with AST from numerical fire dynamics/modeling calculations. In this thesis there is a comparison between simplified Eurocode techniques, simple finite element analysis and advanced finite element analysis. This study shows the benefit of understanding heat transfer in numerical codes and to implement the concept of AST in a proper way.This way, the concept of combining numerical fire dynamics calculation with numerical (or simplified) thermal calculations can be better understood and implemented.

  • 8.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Cheng, Xudong
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Heistermann, Tim
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Travelling fires for CFD2011In: Fire safety science: proceedings of the 10th international symposium : [held at College Park, MD, 19-24 June 2011], London: International Association for Fire Safety Science, 2011, p. 1479-1488Conference paper (Refereed)
    Abstract [en]

    There are numerous methods in structural fire safety engineering to assess a time-temperature input for structural calculations in fire enclosures but there is very little on design fires for CFD calculations. This study is an attempt to explore a simpler form of design fire. The simplified approach consists of two main features, a travelling behaviour and a heat release rate specified by the user

  • 9.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Sjöström, Johan
    RISE.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Thermal exposure from localized fires to horizontal surfaces below the hot gas layer2019Report (Other academic)
    Abstract [en]

    The temperature in the lower chord of steel trusses subjected to localized fires is difficult to estimate as most thermal exposure correlation formulas presented in the literature focus on heating along the ceiling where the temperature is very different from that of the lower chord [1], [2]. At the same time as the upper chord is engulfed in a ceiling jet from a localized fire, the lower chord may be surrounded by air at ambient temperature.Two existing methods by Zhang and Usmani [3] and Guowei et al. [4], [5] along with one new approach for calculating the thermal exposure of the lower chord are presented in this paper and compared to the results from experiments conducted in Trondheim 2015 [6].A new approach presented in this paper is evaluated based on two separate assumptions of the thermal exposure. Outside the plume, the radiative contribution is assumed originating from the plume in the form of a cylinder and inside the plume, the temperature is assumed decreasing according to a Gaussian shape from the central axis temperature to the temperature down to the temperature from the first part of the model at the transition between inside and outside the plume.All models provide good correlation to the experimental data outside the plume perimeter. Inside the plume perimeter, the thermal impact depends to a high degree to the relation between the flame height and the height of the horizontal surface of interest.

  • 10. Sandström, Joakim
    et al.
    Thelandersson, Sven
    Lund universitet.
    Comparing performance-based fire safety design using stochastic modelling to Eurocode partial coefficent methodIn: Article in journal (Refereed)
    Abstract [en]

    In performance based structural fire safety design using the parametric fire curve, Eurocode has adopted a partial coefficient applied only on the fuel load density for calibrating the code to the desired safety level. Probabilistic analyses are presented in this paper to investigate the impact on the reliability due to variation of opening factor, and thermal inertia as well as the ratio between variable and permanent static load. It is shown that the partial coefficient method in Eurocode, with fire exposure expressed via parametric fire curves gives adequate reliability levels with certain margins on the safe side compared to stochastic evaluation based on the same assumptions. This margin is particularly high for load combinations with dominating variable load.

  • 11. Sandström, Joakim
    et al.
    Thelandersson, Sven
    Lund universitet.
    Comparing performance-based fire safety design using stochastic modelling to Eurocode partial coefficent method2018Conference paper (Refereed)
    Abstract [en]

    In performance based structural fire safety design using the parametric fire curve, Eurocode has adopted a partial coefficient applied only on the fuel load density for calibrating the code to the desired safety level. Probabilistic analyses are presented in this paper to investigate the impact on the reliability due to variation of opening factor, and thermal inertia as well as the ratio between variable and permanent static load. It is shown that the partial coefficient method in Eurocode, with fire exposure expressed via parametric fire curves gives adequate reliability levels with certain margins on the safe side compared to stochastic evaluation based on the same assumptions. This margin is particularly high for load combinations with dominating variable load.

  • 12.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Calculation of Steel Temperature in Open Cross Sections Based on Fire Exposure from CFD2015In: The 13th Nordic Steel Construction Conference: NSCC-2015 / [ed] Markku Heinisuo; Jari Mäkinen, Tempere: Tampere University of Technology, Department of Civil Engineering , 2015, p. 195-196Conference paper (Refereed)
    Abstract [en]

    Evaluation of steel temperature for small and complex structural elements directly in FDS introduces local effects which can lead to over prediction of the solid temperatures. The sol-id temperature calculation in FDS is based on a one dimensional assumption and cannot handle all the aspects of heat loss due to conduction. FDS is therefore likely to over predict the temperature in, for example, the web in open cross sections. In this paper, this issue is demonstrated and handled with by the use of shadow effects in FE analysis. Two different methods handling the local effects are presented. The different methods show different lev-els of accuracy presenting a more complete method for thermal response calculations based on numerical calculations of experimental data.

  • 13.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering. SP Technical Research Institute of Sweden, Borås.
    Steel temperature calculations in performance based design: Advanced techiques for thermal response calculations with FE-Analysis2013In: Proceedings of International Conference in Prague 19-20 April 2003: Applications of Structural Fire Engineering / [ed] Wald F.; Burgess I.; HorováK.; JánaT.; Jirk J., 2013, p. 153-159Conference paper (Refereed)
    Abstract [en]

    By using advanced FEA techniques, the predicted temperature in steel elements can be reduced significantly (see paper by Ulf Wickström). By in addition assuming a performance based fire exposure obtained with numerical fire models such as Fire Dynamics Simulator, FDS, the steel temperatures can be even further reduced.

     

    Most calculation methods assume the fire exposure of the steel sections to be uniform. By using section factors A/V, i.e. the circumference over the area, and the most onerous of the fire exposing temperatures from computer fluid dynamics, CFD, calculations, the temperatures is over-estimated which leads to very conservative and costly solutions.

     

    By considering the cooling effect of concrete structures and shadow effects, the temperatures can be reduced in the steel. By combining differentiated fire exposing temperatures from CFD calculations with consideration to shadow effects and the cooling of concrete, the temperature in the steel beam can be reduced even further.

  • 14.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    Thelandersson, Sven
    Lunds universitet.
    Lagerqvist, Ove
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Fire Engineering.
    The Life Safety Objective in Performance-Based Design for Structural Fire Safety2017Conference paper (Refereed)
    Abstract [en]

    Structural stability is not necessarily required for buildings where life safety is the sole structural fire safety objective. However, a structural collapse is only acceptable in an area where lethal fire conditions have developed. Therefore, structural failures due to fire resulting in risks of progressing outside of the area of lethal fire conditions need to be addressed. Thus, a new type of design principles for the life safety objectives is presented here which enables an evaluation of more precise risk assessments and more cost-efficient solutions without compromising human safety.

  • 15.
    Sandström, Joakim
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Wickström, Ulf
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Veljkovic, Milan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Iqbal, Naveed
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Structural and Construction Engineering.
    Sjöström, Johan
    SP Sveriges Tekniska Forskningsinstitut, Brandteknik.
    Sundelin, Johan
    Fastec Sverige AB.
    Steel truss exposed to localized fires: Experimental report from a large scale experiment with a steel truss exposed to localized fires2015Report (Other academic)
1 - 15 of 15
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