František Wald

Performance-based fire engineering of structures

Introduction to Fire Safety Engineering and the Role of Structural Fire Engineering Introduction to fire engineering Roles of structural fire resistance The process of performance-based fire engineering of structures Introduction to the book Recent Major Structural Fire Events and Their Implications Introduction Broadgate fire, London, 1990 Cardington fire research programme, 1994-2003 World Trade Center collapses, 11 September 2001 Windsor Tower fire, Madrid, 12 February 2005 Summary and context of this book Introduction to Enclosure Fire Dynamics Introduction Standard fires Fires in small compartments Fires in large compartments and travelling fires Computer models of compartment fires Heat Transfer Introduction Basics of heat transfer Convective heat transfer coefficients Radiant heat transfer coefficient Some simplified solutions for heat transfer Importance of using appropriate thermal properties of materials Effects of thermal boundary conditions Brief introduction to numerical analysis of heat transfer Concluding remarks Material Properties Introduction Structural materials Fire protection materials Concluding remarks Element Structural Fire Resistance Design Design principles Concrete structures Steel structures Composite steel and concrete structures Timber structures Masonry structures Aluminium structures Fire resistance design worked examples Global Modelling of Structures in Fire Introduction Nature of global structural behaviour in fire Analytical methods for structures in fire Practical modelling techniques Steel and Composite Joints Introduction Typical joints at ambient temperature and in fire Current design Development of performance-based approaches Integrity of Compartmentation Introduction Issues affecting internal walls Design of slabs for integrity in fire Robustness of Structures in Fire Introduction Causes of fire-induced disproportionate collapse Design strategies Catenary action Requirements for connections Other considerations Summary The Practical Application of Structural Fire Engineering for a Retail Development in the United Kingdom Introduction Methodology Design fires Acceptance criteria Finite element analyses Steel beam connections Simplified methods Comparison between Vulcan and simplified methods Conclusions References

Embedded steel column bases: I. Experiments and numerical simulation

Testing and numerical modelling of embedded steel column bases are discussed in this paper. The behaviour of two different types of experimental specimen has been analysed. The specimens were specifically designed so that the bond and punching resistances of the steel column bases could be quantified. Numerical modelling by the finite element method (FEM) has been conducted to investigate the stress distributions in column bases. The numerical results have been calibrated against the test results. The testing and numerical modelling described provide a basis for establishing a design model that will be introduced in Part II of this paper.

The Paramount Role of Joints into the Reliable Response of Structures

Foreword. Workshop Participants. I. Behaviour of Structures Including Joint Behaviour. II. Experimental Studies of Joints and Frames. III. Behaviour of Earthquake Resistant Structures Including Joint Behaviour. IV. Numerical Simulation of the Structural Response of Joints and Frames. V. Analytical Models for Joints and Reliability. Authors Index. Subject Index.

Embedded steel column bases: II. Design model proposal

Abstract A design model for an embedded steel column base is proposed in this part of the paper. The proposed model introduces the calculation for the moment, shear and vertical resistance by the use of plastic stress distribution analysis. The design model is based on the experimental results and numerical modelling described in Part I of this paper (Pertold J, Xiao R, Wald F. Embedded column base Part I. Experiment and numerical simulation. Journal of Construction Steel Research). The proposed model reduces the length of embedded column needed to transfer loading forces. Shear and vertical resistance calculation methods have also been improved. Compared with existing experimental results it indicates that the design model is safe and accurate.

Component Method for Historical Timber Joints

Timber structures represent one of the most important ancient engineering works spanning over considerable distances. They involve not only an evidence of structural knowledge and creativity of their makers but also a good deal of structural beauty, Figure 1.

Proposal of the stiffness design model of the column basis

The connection between the steel column footing and the concrete foundation has a rotational rigidity significant for the overall frame analysis. This rigidity could be taken into account to predict the horizontal drift of the frame in serviceability limit state. A pi J posal of the stiffness design model compatible with stiffness prediction according to Eurocode 3. Annex J is presented in the paper. The model is based on the component method. Three patterns of the base plate internal forces distribution represent different collapse modes based on axial force - total bearing capacity ratio. The prediction model is compared to experimental observations. A parametric study of the main parameters of the model is included.

Temperature of connections during fire on steel framed building

To study the global structural and thermal behaviour of buildings in fire, a research project was conducted including a fullscale test on a three storey steel frame building at Mittal Steel Ostrava before demolition. The main goal of the experiment was to verify the method for predicting joint temperatures and to improve it for the cooling phase. The fire compartment extending over a floor area of 24 m2 was built on the second floor. The fire load was 140 kg/m2 of wood and the ventilation was limited to an opening of 1,400 × 1,970 mm. This paper presents the time-temperature curves showing the development of the fire in the compartment and in the primary and secondary beams and its header plate connections. Comparisons are made between the test results and the temperatures predicted by the structural Eurocodes. The sensitivity of the connection behaviour to the estimated temperatures and associated degradation in material properties during the fire is demonstrated.

Temperature heterogeneity during travelling fire on experimental building

Temperature distribution in medium fire compartment is investigated experimentally.Numerical simulation of the travelling fire test is completed by using FDS.Measurements from the travelling fire test are used to validate the simulation.Travelling fire is compared to compartment fire with uniform temperature conditions.A potential impact of temperature heterogeneity on a structure is highlighted. In order to follow modern trends in contemporary building architecture which is moving off the limits of current fire design models, assumption of homogeneous temperature conditions used for structural fire analysis needs to be validated. In this paper it is described, how temperature distribution in a medium-size fire compartment has been investigated experimentally by conducting fire test in two-storey experimental building in September 2011 in the Czech Republic. In the upper floor, a scenario of travelling fire was prepared. It has been observed that as flames were spreading across the compartment, considerable temperature gradients appeared. Numerical simulation of the travelling fire test conducted using FDS (Fire Dynamics Simulator) has been compared with simulation of compartment fire under uniform temperature conditions to highlight the potential impact of the gas temperature heterogeneity on structural behaviour. The temperature measurements from the fire test have been used for validation of the numerical simulation of travelling fire. The fire test has provided important data for design model of travelling fire and shown that its impact on structural behaviour is not in agreement with the assumption of homogenous temperature conditions.

Stiffness of cover plate connections with slotted holes

Abstract This paper describes the prediction of stiffness of bolted cover plate connections with slots perpendicular to the acting force. The work is based on three sets of tests: experiments on connections with more bolt rows and different bolt forming technology performed at the CRIF laboratory in Liege, experiments with long slots completed at the Laboratory of Technical University Nottingham, and experiments with components carried out at the Czech Technical University in Prague. The work shows the application of the component method to the prediction of stiffness of the cover plate connections. The component bolt/plate in bearing is evaluated. Special attention is paid to the modelling of the bolt force distribution for different bolt tolerances.

Design of haunches in structural steel joints

AbstractThe paper presents research in design of haunches in structural steel joints. Experimental results of six specimens of haunches with and without flanges are presented. Three specimens are without flanges and three specimens are supported by additional flanges. Flanges differ in stiffness to observe the increase in haunch resistances and the effect on buckling shapes. The research finite element model (RFEA) is studied by material and geometrical nonlinear finite element analysis with imperfections under the actual stress conditions and validated on the measured experimental data. The validity is demonstrated on the comparison of load-deflection curves, failure modes, stress distributions and yield line patterns. The stability analysis of a joint with a haunch is related to the research into component based finite element models of complex joints. The input and the results of the research finite element model are summarised in a benchmark case of a haunch with a flange. A numerical study illustrate...