Software implementation of assessment of buildings' resistance to progressive collapse

Maiboroda Roman

National University of Civil Protection of Ukraine

http://orcid.org/0000-0002-3461-2959

Otrosh Yurii

National University of Civil Protection of Ukraine

http://orcid.org/0000-0003-0698-2888

DOI: https://doi.org/10.52363/2524-0226-2025-41-12

Keywords: progressive collapse, fire, explosion, LIRA–SAPR, computer model, load combination

Аnnotation

A computer model has been developed that allows assessing the resistance of a reinforced concrete monolithic building to progressive collapse under the influence of the combined action of fire and internal deflagration explosion. For this purpose, a spatial physically and geometrically nonlinear model of a six-story industrial building was created. The model takes into account the combined operation of load-bearing structures, changes in the thermophysical and mechanical properties of materials under the influence of elevated temperatures, the formation of local destruction, redistribution of internal forces and dynamic effects from explosive loading. The model is implemented in the LIRA-SAPR software package using the “thermal conductivity” module to take into account the temperature effect of a standard fire regime lasting 60 minutes and the “dynamics in time” settings to simulate an impulse load from an explosion of 15 kPa. As a result of the modeling, it was established that the isolated action of a fire leads to an increase in the deflections of the floor slabs by 2.6 times, and an internal explosion leads to an increase in the deflection of the bottom slab by 5.2 times relative to the normal state. The greatest danger is the scenario of the combined impact of fire and explosion, in which the deflection of the lower plate reached 55.8 mm, which exceeds the initial value by 8.3 times. Such deformations, when combined, can potentially cause the loss of the load-bearing capacity of structures and the development of progressive collapse of the building. The results obtained form the basis for increasing the level of structural safety of buildings and reducing the risk of loss of human lives in emergency situations. The proposed approach provides the possibility of a comprehensive assessment of the resistance of reinforced concrete monolithic buildings to progressive collapse under the combined action of thermal and explosive loads, as well as the justification and implementation of effective measures to increase their reliability and survivability.

References

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Determining the minimum water pressure for supplying it for cooling the tank

Basmanov Oleksii

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-6434-6575

Oliinik Volodymyr

National University of Civil Protection of Ukraine

http://orcid.org/0000-0002-5193-1775

Morshch Evgen

State Research Institute of Cybersecurity and

Information Protection Technologies

http://orcid.org/0000-0003-0131-2332

Kalchenko Yaroslav

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-3482-0782

DOI: https://doi.org/10.52363/2524-0226-2025-41-10

Keywords: fire nozzle, cooling water supply, water jet trajectory, flat trajectory

Аnnotation

A model of the water jet motion after exiting the fire nozzle has been constructed. The model is based on a system of linear homogeneous and linear inhomogeneous 2nd-order differential equations with initial conditions that describe the motion of an elementary volume of water in a gravitational field and take into account air drag. Their solving with the initial conditions gives the trajectory of the water jet motion depending on the horizontal and vertical components of the initial jet velocity. The dependence of the water pressure on the horizontal component of the water jet velocity at the fire nozzle provided that the jet reaches a given point on the tank shell has been constructed. It is shown that the dependence is a downward convex function with a single minimum point. Only one trajectory of the jet motion corresponds to the minimum water pressure, which reaches a given point. An increase in the pressure leads to the appearance of two possible trajectories, one of which is grazing, and the other can be grazing or flat. It is shown that the condition for the trajectory to be flat is that the horizontal component of the velocity exceeds a certain limit value that is proportional to the distance to the tank. An algorithm for determining the minimum water pressure for supplying to a given point on the tank shell by a flat trajectory is constructed. The algorithm uses Newton’s method to numerically solve the conditional optimization problem. It is shown that for a distance to the tank (5÷30) m the water pressure should be (23÷58) m for tanks 12 m high and (37÷70) m for tanks 18 m high. The obtained results can be used to determine the locations of fire nozzles for supplying water to cool tanks while developing a plan for localizing and eliminating fires in a oil tank storage and to reduce water losses due to the splattering of the jet after hitting the tank.

References

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4. Amin, M. T., Scarponi, G. E., Cozzani, V., Khan, F. (2024). Improved pool fire-initiated domino effect assessment in atmospheric tank farms using structural response. Reliability Engineering & System Safety, 242, 109751. doi: 10.1016/j.ress.2023.109751
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Мodeling the deployment of rod structures as multilink pendulums under microgravity conditions

Kalynovskyi Andrii

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-1021-5799

Kutsenko Leonid

National University of Civil Protection of Ukraine

http://orcid.org/0000-0003-1554-8848

Sukharkova Olga

National University of Civil Protection of Ukraine

http://orcid.org/0000-0003-1033-4728

Nazarenko Sergii

National University of Civil Protection of Ukraine

https://orcid.org/0000-0003-0891-0335

Diachkov Oleksandr

National University of Civil Protection of Ukraine

http://orcid.org/0000-0002-7978-0024

Hrynko Yurii

National University of Civil Protection of Ukraine

http://orcid.org/0000-0003-1957-025X

DOI: https://doi.org/10.52363/2524-0226-2025-41-11

Keywords: core construction, process of opening in space, multi-link pendulum, Lagrange equation

Аnnotation

A new approach to modeling the transformation of rod structures in microgravity by investigating elements of their frameworks, represented as multi-link pendulums. A geometric model is presented for the deployment of such structures under the influence of pulsed thrusts from jet engines mounted at the endpoints of the links. The deployment mechanism is based on initiating inertial motion without continuous external control after a brief impulse application. The dynamics of the deployment process are described using Lagrange’s equations of the second kind, with particular emphasis on adapting the formulation to microgravity conditions, where potential energy can be considered negligible. This enables accurate modeling of structure deployment driven solely by kinetic energy, without further external control. As a result of the impulse action, the pendulum deploys by inertia, justifying the use of the term «inertial deployment method» for the frame. Mathematical models and a computer animation method are developed to predict the time evolution of link positions and to determine the fixation moment («stop code») for achieving the desired structure geometry. The influence of impulse magnitude errors on deployment accuracy is studied, and acceptable tolerance limits are established to maintain a satisfactory configuration. Test examples are provided for the deployment of double-link and four-link pendulums, as well as special configurations such as the Magdeburg pendulum and the Thomson-Tait pendulum. The obtained results are well-suited for animation to visualize the dynamics of rod structure formation—for example, illustrating the deployment of support frameworks for solar mirrors or space antennas. The proposed methods allow for the simplification of deployment technologies for large space objects, eliminating the need for complex electromechanical drives and thus reducing the mass and cost of space missions.

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Study of the influence of sodium hexametaphosphate on the properties of silica-containing fireproofing coating for building materials

Lysak Nataliia

National University of Civil Protection of Ukraine

https://orcid.org/0000-0001-5338-4704

Skorodumova Olga

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-8962-0155

Chernukha Anton

National University of Civil Protection of Ukraine

https://orcid.org/0000-0002-0365-3205

Goncharenko Yana

National University of Civil Protection e of Ukraine

https://orcid.org/0000-0002-1766-3244

Melezhyk Roman

National University of Civil Protection of Ukraine

http://orcid.org/0000-0001-6425-4147

DOI: https://doi.org/10.52363/2524-0226-2025-41-9

Keywords: fire-retardant silica-containing coatings, sodium hexametaphosphate, building materials, heat resistance, fire resistance, wood, polystyrene foam

Аnnotation

The composition of a silicophosphate composition intended for fire protection of building materials was developed. Solutions of liquid glass, acetic acid and sodium hexametaphosphate were used as starting components. The influence of the content of the phosphorus-containing additive on the rheological properties of silicic acid sols was studied. By spectrophotometry, it was established that the latent coagulation time in the entire range of the studied content of sodium hexametaphosphate is ~20 minutes. The highest values of optical density were recorded for a sol with an additive content of 0.3 %. The probability of the influence of electrostatic and steric effects, which depend on the concentration of the phosphorus-containing additive, on the stability of the sol was considered. It is assumed that the minimum value of sol survivability at 0.3 % of the additive is associated with a decrease in the ζ-potential and compression of the double electric layer. The results of infrared spectroscopy confirmed the hypothesis of two different mechanisms of polycondensation in different intervals of hexametaphosphate content. At a content below 0.3 %, a linear mechanism of polycondensation was noted, above 0.3 % – a reticular one. Fire tests were carried out on samples of wood and extruded polystyrene foam coated with compositions of the studied composition. The best fire-retardant properties were recorded for systems with a sodium hexametaphosphate content of 0.1–0.3 %. Processing of wood samples allowed transferring the material to the “hard-to-flame” group, the mass losses of the samples were less than 10 %. Samples of extruded polystyrene foam did not support combustion at an additive content of 0.1 % or did not burn at all at a content of 0.3 %, mass losses were less than 3 %. The effect of the number of coating layers on the effectiveness of its fire-retardant action was assessed: for wood in the range of hexametaphosphate concentrations of 0.1-0.3 %, three-layer coatings were the most heat-resistant, for extruded polystyrene foam at a content of 0.3 % – one- and two-layer.

References

1. Hou, X., Guo, L., Wang, F. (2021). Inhibiting effects of three phosphates on coal spontaneous combustion. International Journal of Coal Preparation and Utilization, 42(10), 3054–3069. doi: 10.1080/19392699.2021.1932844
2. Zhu, Z., Rao, W., Kang, A., Liao, W., Wang, Y. (2018). Highly effective flame retarded polystyrene by synergistic effects between expandable graphite and aluminum hypophosphite. Polymer Degradation and Stability, 154, 1–9. doi: 10.1016/j.polymdegradstab.2018.05.015
3. Ji, W., Yao, Y., Guo, J., Fei, B., Gu, X., Li, H., Sun, J., Zhang, S. (2020). Toward an understanding of how red phosphorus and expandable graphite enhance the fire resistance of expandable polystyrene foams. Journal of Applied Polymer Sci-ence, 137(35). doi: 10.1002/app.49045
4. Liu, J., Guo, Y., Chang, H., Li, H., Xu, A., Pan, B. (2018). Interaction between magnesium hydroxide and microencapsulated red phosphorus in flame‐retarded high‐impact polystyrene composite. Fire and Materials, 42(8), 958–966. doi: 10.1002/fam.2650
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