Probabilistic assessment of factors influencing façade fire formation and extension

This paper presents a detailed analysis of the dynamics of indoor environmental parameters under three simulated fire scenarios in a multi-story building, using the PyroSim platform (based on the Fire Dynamics Simulator—FDS). The study compares two smoke control strategies, organized natural ventilation (a passive system) and mechanical pressurization (an active system), evaluating their influence on temperature, differential pressure, air velocity, heat release rate (HRR), and toxic gas distribution. The simulations revealed that passive systems, relying on the stack effect and vertical natural ventilation, do not ensure the effective control of smoke infiltration into evacuation routes, allowing significant heat accumulation and reduced visibility. The results highlight the superior effectiveness of unidirectional mechanical pressurization in maintaining a stable flow regime, functional visibility, and a safe evacuation environment. A key finding is the transition from static pressure control to velocity-based flow control at the moment of door opening toward the fire source. The results confirm that a dynamically adapted application of mechanical pressurization—synchronized with the opening of access pathways—not only reinforces existing principles for protecting egress routes, but also provides a precise operational approach for optimizing emergency responses in high-rise buildings.

Due to their complex structures and high occupancy, multi-storey buildings face significant fire risks. Effective evacuation must consider crowd dynamics and changing environments. Therefore, it is particularly urgent to develop intelligent evacuation systems that can assist in identifying complex environments and provide real-time and effective guidance. To address this need, the study proposes a novel bootstrap program that integrates various technical knowledge, uses CFD fluid dynamics simulation technology and LK pyramid optical flow method to realize the dynamic behavior analysis of people in this complex scene, combines DFS path planning algorithm and multi-threading concurrency technology. The intelligent evacuation system proposed in this project is based on computer vision technology. It comprehensively considers the complex environmental factors of fire scenarios, significantly enhancing evacuation efficiency, reducing casualties and property losses, and contributing to urban safety and social stability.

Multi-storey car park buildings with steel–concrete composite floor structures are widespread in construction due to the distinct benefits of the implemented structural system. Although there are various possibilities for accomplishing composite action between a steel beam and a concrete slab, some solutions, such as friction-grip bolts commonly applied in the 1970s, did not show good durability. An example is the multi-storey car park building “Obilićev venac” in Belgrade. This case study presents two methods for life extension of the car park building structure. Both approaches focus on applying welded headed studs with the primary intention of providing a durable shear connection. While the first method has been applied during the structure’s reconstruction, the second method is proposed as a novel solution for implementation in steel–concrete composite floors. The application of the proposed connection is discussed and the results of the experimental and numerical research conducted are presented.

In-cell solvent fire has been treated globally as a typical accident of a reprocessing plant. In order for the fire to break out, leakage of a significant amount of solvent, a temperature rise above its flash point, and the presence of ignition source have to occur simultaneously. In this paper, such an accident was analyzed from a probabilistic viewpoint. The occurrence frequency was shown to be 10−7/y because a frequency or probability of each event is so small. Nevertheless, we assumed the fire occurring for 1 h. One hour should be enough for the assessment of the consequence because an operator can implement measures to extinguish the fire by inducing oxygen deficiency in the cell, such as closing a fire damper or stopping the exhausting fan. Since a certain amount of soot produced by fire does not deteriorate the function of a HEPA filter, the effective dose for the general public is less than 0.1 mSv. The results will be useful for judging the safety importance level of the safety measures against fire.

Surrogate SDOF models for probabilistic performance assessment of multistory buildings: Methodology and application for steel special moment frames

PURPOSE. The problem of prompt and efficient fire suppression in high-rise buildings is getting more relevant in view of increase in the number of floors in residential buildings nowadays. The aim of the given work is to conduct an analytical review and identify the main features of extinguishing fires in high-rise buildings with the help of technical means delivering extinguishing agents to the height. METHODS. The authors used methods of mathematical statistics, systems analysis and expert assessments. FINDINGS. The analysis of fires in multi-storey residential buildings in the Russian Federation made it possible to reveal the trend towards increase in fires in such buildings over the past few years. Kitchen and living rooms are still the main source of ignition. And the problem of delivering extinguishing agents to the height remains relevant. Three scenarios of fires for different floors were simulated and schemes for delivering extinguishing agents with the help of mobile means of fire extinguishment were proposed. Fire-fighting equipment and its weight necessary for extinguishing fires were calculated. The probability of the injury rate growth due to increased load on firemen while extinguishing fires at these facilities was brought out. RESEARCH APPLICATION FIELD. The outcomes of the research can be used when studying specifics of fire development in multi-storey residential buildings in order to further improve technical means of fire extinguishment. CONCLUSIONS. Developing and introducing “gentle” means for delivering extinguishing agents in enclosed spaces will allow minimizing damage from excessive water delivery onto fires, and improving ergonomic parameters of fire-fighting equipment will make it possible to speed up laying main and working lines and also to reduce the level of injuries among firefighters due to exhaustion.

Modelling and numerical simulation of pedestrian flow evacuation from a multi-storey historical building in the event of fire applying safety engineering tools

Staircases are very important from the point of view of fire protection. There are several reasons for this standpoint, but two are particularly significant. The first is that stairs are an important means of evacuation in multi-storey buildings, and the second is that the moment of detection of fire is crucial for the beginning of the evacuation. The first fact refers to the stair’s location in buildings and the dimensions of stairs and landings. The importance of the second fact is obvious – the location and numbers of fire detectors directly affect early fire detection, and consequently the beginning of evacuation. The worst-case fire scenario from the aspect of building design - a staircase in the center of the building - was chosen for the simulation described in the paper, because in Serbia, there are many structures like this For the simulation described in the paper, the worst-case fire scenario was selected from the aspect of building design - a staircase in the centre of the building, because there are many, such in our country. On the other hand, recommendations for the location and number of fire detectors on a staircase are different in world-leading standards. For these reasons, in this paper, the simulations were performed in an eight-story building for various dimensions of spaces between stairs. On the basis of a comparison of the regulations outlined in European, British, German, American, and Russian standards, simulation parameters are defined. Parameters for simulations are defined on the basis of a comparative analysis of rules stated in European, British, German, American and Russian standards. Taking into account that some emergency evacuations entail moving through smoke-filled areas, building engineers must understand how the aforementioned factors affect smoke development in the event of a fire, and thus effective evacuation.

Robust fire design of single plate shear connections

This paper briefly reviews the main fire scenarios for exterior facade claddings on multi-storey buildings, together with available full-scale test procedures and performance requirements in different countries. It is obvious that there is no international agreement or approach on how to evaluate the fire safety of facade claddings. Two series of full-scale fire tests of wooden facades, in accordance with the Swedish SP Fire 105 test, are presented: one series for different proportions of untreated wood (partial wood and structural fire protection with a fire shield above the window), and another series for fire-retardant-treated wood. The results are compared with data from the intermediate scale Single Burning Item test and the small scale cone calorimeter test. A main conclusion is that SP Fire 105 is a useful tool to evaluate the fire behaviour of facade claddings, but it should be complemented with more objective measurements. Claddings with partial wood and the use of a fire shield above the window fulfil the requirements. Wood claddings treated with fire retardants (FR) may fulfil the requirements, if the amount of FR is high enough. It is also essential to demonstrate the weather durability of the FR treatment. Good agreement has been found with the other test methods used. The need to use fire stops behind multi-storey facade claddings to avoid the spread of fire in cavities is underlined.

Residual drifts are routinely used to assess the post-earthquake safety of buildings. Despite their importance, studies on the probabilistic assessment of residual drifts in multi-storey buildings with Steel Moment Resisting Frames (SMRF) are far less common than those dealing with their transient peak drift counterpart. More seriously, although residual drift prediction models have been developed with a particular broad ground-motion type or soil condition in mind, all models proposed to date remain oblivious to the central issue of hazard consistency. Hence, missing the causal connection between the seismic hazard level and the ground-motion suite used and potentially compromising the meaningfulness of their results. This oversight is expected to introduce a bias in the estimation of residual drifts but its magnitude has not yet been properly evaluated. In this paper, we evaluate and quantify the significance of these effects. To this end, we use the Conditional Scenario Spectra framework, which provides a set of realistic earthquake spectra with assigned rates of occurrences based on their spectral shape and intensity, thus preserving the critical relationship of hazard consistency. Nonlinear Response History Analyses (NRHA) of 24 deteriorating SMRFs under 816 ground-motion records are performed to construct a database of residual drift demands. These NRHA results are used to examine the residual drift trends and to construct benchmark residual drift hazard curves. An extensive feature selection process employing several Machine Learning (ML) algorithms precedes the development of hybrid data-driven predictive models. Finally, we compare our hazard-consistent predictions with currently available models and quantify the massive under- and over-estimations associated with previously proposed non-hazard-consistent assumptions.

Location based services (LBS) require a reliable, accurate and continuous position determination of mobile users. This is particularly true in indoor environments where the widely used Global Positioning System ( GPS) is not available due to its signal outages. One solution is to integrate different techniques in a multi-sensor positioning system to overcome the limitations of a single sensor. In this chapter an approach is described using a three-dimensional Radio Frequency Identifi cation (3D RFID) location fi ngerprinting probabilistic approach with map-based constraints in order to provide reliable positions in indoor 3D environments. An Extended Kalman Filter (EKF) is used to integrate 3D RFID positioning method with an Inertial Navigation System (INS) in order to produce an accurate and continuous positioning estimation.The multi-storey experiments conducted at RMIT University, Australia, show that the 3D RFID positioning method can determine the mobile user’s movements in a kinematic mode to meter-level by using the fi ngerprinting probabilistic approach. The smoothing method and the RFID/INS integration can both improve the positioning accuracy by tackling the RSS instability problem. Besides the 100Hz updating rate, the RFID/INS integration method can provide more reliable estimation based on the mobile user’s kinematic characteristics rather than simply smoothing the estimations. The results also show that the algorithms for the Integrated RFID/INS indoor positioning system developed can satisfy the requirements for personal navigation services.

Seismic design of concrete structures is currently based on time-invariant capacity design criteria which do not account for environmental hazards. The significant progressive decay of strength and ductility of concrete structures exposed to damage, in particular due to reinforcing steel corrosion, shows that this approach should be revised to consider the deterioration over time of the seismic performance. This is important also for precast systems, for which most of structural members are often directly exposed to the atmosphere and environmental aggressiveness. This paper presents a probabilistic approach for the lifetime assessment of seismic performance of concrete structures considering the interaction of seismic and environmental hazards. The effectiveness of the proposed approach is shown by its application to multistory precast buildings exposed to corrosion. The results show that structures designed for the same seismic action could have different lifetime seismic performance depending on the environmental exposure. These results emphasize the importance of a life-cycle approach to both seismic assessment of existing buildings and seismic design of new structures, and indicate that capacity design criteria need to be properly revised to consider the severity of the environmental exposure.

The reliability of reinforced concrete structures of multistory residential and office buildings subjected to gravity and reiterated lateral loading is under consideration. Slab-wall and beam-column structures and their joints of reinforced concrete buildings should be designed to resist normal and shear action effects resulting from gravity forces caused by permanent and useful live loads and lateral forces caused by reiterated short duration episodic wind gusts or seismic actions (Fig 1). A random loading and overloading of relatively rigid joints by reiterated and variable in time transient lateral forces are very dangerous in reliability sense. Therefore, the strength analysis of flexural members of redundant systems must be formulated and solved in the probabilistic approach methods. Nonlinear behaviour of members are caused by material and geometrical non-linearity and depends on the inelastic hysteretic response of the slabs and beams in bending and shear. The equilibrium equation of the non-linear hysteretic system is presented in formula (2) where M is the mass matrix; C is the damping matrix; K is the stiffness matrix; L is the load vector; Ü, U, U are the model accelerations, velocities and displacements vectors. The action effect of horizontal or vertical members can be evaluated by the formulae (3,4,5), where α j is the transposed row of the influence matrix α. The probability distribution of member's strength and gravity forces is close to the normal one [4, 5, 6]. The probability distribution of annual extreme values of wind gusts obey Gumbel or Fisher-Tipet distribution laws [7, 8]. Therefore, for structural safety analysis of flat floor slabs, frame beams, and joint cores of their connections to walls and columns can be adjusted by the method of limit transient action effect based on the compound Poisson-Gumbel distribution law. The long duration safety factor for flexural members can be evaluated by formulae (26), (28) and (37). Here “r” is the number of reiteration episodic lateral loads. The method of limit transient action effect as simplified and rather accurate probabilistic approach to the verification analysis and structural quality estimation of reinforced concrete slab-wall and beam-column structural members and their joints permit to enlarge the successive progressive versions of Eurocode 1.

The paper presents a comprehensive study on oriented strand boards (OSB) and gypsum fiber boards (GFB) as sheathing materials for light-frame wall elements. The study is based on the experimental results of the research project, optimization of multistory timber buildings against earthquake impact (OptimberQuake). In the framework of this project, 20 light-frame wall elements and 58 sheathing-to-framing connections with different layouts have been tested under cyclic and monotonic loading. The experimental results have been analyzed and compared in terms of ductility, energy dissipation as well as deformation, and load-bearing capacity. Furthermore, the performance of the walls was evaluated with the probabilistic approach in accordance with current methodology. For this purpose, a simplified numerical model was used in which the walls were represented by an equivalent nonlinear shear springs. The characteristics of the springs were determined based on the experimental results wherein the response was described by a hysteretic model. As a result of probabilistic analysis, behavior factor (i.e., force reduction factor) was evaluated for walls with different types of sheathing. The analysis of the experimental results and probabilistic approach led to the same conclusions. The results show a comparable cyclic response of timber framed walls covered with OSB or GFB boards in terms of energy dissipation and deformation capacity. The probabilistic assessment also suggests that the same behavior factor can be used for both types of wall if the basic requirements regarding the minimum thickness and detailing of the connections are met. A higher value for the minimum thickness of GFB compared with OSB will be recommended.