Automated fire risk evaluation of electrical installations in the man-machine system

The article considers approaches to the formation of a system of criteria for assessing the electrical installations fire condition of the agricultural and industrial complex. Based on the analysis of the literature, the conclusion is made about the appropriateness of the use of expert assessments. To implement the decision, a group of experts was assembled, on the basis of whose knowledge a list of 42 parametersζ characterizing the fire condition of the electrical installation was determined. To identify the relationships and form a method for calculating the estimated value of fire risk, experts assessed the fire condition of 70 electrical installations of the agricultural and industrial complex of the region. A knowledge base was formed from the resulting values. As a method of data analysis, it was decided to use neural networks, but the available sample is not sufficient for high-quality training of a neural network. Therefore, the correlation method and the principal component method were considered, and based on the calculations, it was decided to use a training sample consisting of 6 principal components for training a neural network. A neural network was trained on these data and the values of the average error were obtained sufficiently low, which may indicate sufficient accuracy of the generated model. The article also presents a conceptual scheme of a software package for automating calculations in accordance with the developed model.

Calculation of reinforced concrete beams’ shear strengths at ambient and fire conditions according to Russian design standards

This paper introduces general principles and gives analytical clarifications of the stirrups design at ambient condition and shear strength analysis for reinforced concrete (RC) beams at fire condition according to Russian design standards SP 63.13330.2012 (SP 63) and SP 468.1325800.2019 (SP 468), respectively. The calculation method on inclined cross section (ISC) and the simplified approach on normal cross section (NSC) are clarified and developed so that the stirrups configuration can be directly designed at ambient condition and the deterioration of shear strength when the beam is exposed to ISO 834 fire can also be explicitly determined. Calculation results of a case study conducted in the paper show that although there are certain gaps between the designed results of stirrups using ICS and NCS methods, the fire resistances based on shear strength criteria obtained from the two methods are similar. With the systematic nature between the design standards TCVN 5574:2018, SP 63 and SP 468, it is rational to use SP 468 as a reference for RC structural fire design that is compatible with QCVN 06:2021/BXD and TCVN 5574:2018, before any advanced international code is decided to be applied in Vietnam.

Research on Fire Test Method of High Pressure Hydrogen Storage Cylinders for Transportation

As important equipment in the entire hydrogen industry chain, composite hydrogen storage cylinders for transportation have developed rapidly in recent years. The fire test is used to verify the explosion resistance of gas cylinders under specified fire conditions. Compared to steel gas cylinder, composite gas cylinder is more dangerous in the fire condition. The wound layer, as the main pressure-bearing structure of the composite hydrogen storage cylinder, is inflammable. In the case of fire, the mechanical properties of the cylinder will degrade quickly due to the high temperature. If the gas inside the cylinder cannot be discharged in time, the cylinder explosion will occur. Currently, some relevant standards or standard drafts have been drawn up by the international organizations, which are useful for formulating Chinese standard for hydrogen storage cylinders for transportation. The applicable scope of the standards was discussed in this paper, such as composite cylinder type, working pressure, nominal volume and design life, etc. The fire test methods of composite gas cylinders in various standards were compared and analyzed, such as experiment method, cylinder placement method, cylinder filling requirements, fuel selection, fire source setting, temperature measurement requirements, and qualified indicators, etc. Finally, the challenges for development of composite hydrogen storage cylinders and compressed hydrogen storage systems in China were proposed.

Numerical Simulation on Fire Test of 45 MPa Hydrogen Storage Vessels for Hydrogen Stations

In recent years, there have been a number of fire and explosion accidents of hydrogen storage vessels in hydrogen stations all over the world. China is vigorously developing the hydrogen fuel cell vehicle industry. At present, more than 80 hydrogen refueling stations have been built, and 1000 hydrogen refueling stations are planned to be built in 2025. In order to study the response law and pressure relief requirements of hydrogen storage vessels in hydrogen refueling stations under fire condition, fire tests of hydrogen storage vessels filled with high pressure hydrogen is planning to carry out. In this paper, numerical simulation of fire tests of hydrogen storage vessels was carried out. The hydrogen storage vessel is a horizontal single-layer seamless structure with working pressure of 45 MPa, wall thickness of 35.4 mm, volume of 205 L and material of 4130X. Propane is used as fuel for fire test. Based on CFD software, the thermal structural response calculation model of the hydrogen storage vessel under fire condition was established. The response law of hydrogen temperature rise and pressure rise in the hydrogen storage vessel was analyzed, and the influence of filling medium, filling pressure and ambient temperature on the hydrogen storage vessel was studied. The research results provide technical guidance for the subsequent fire test of the hydrogen storage vessels.

Review of Post-Fire Inspection Procedures for Concrete Tunnels

It is well known that concrete structures can lose strength and long-term durability after a fire. The literature on the remaining capacity of tunnel structures after fire is quite scattered, however, and few published post-fire inspection guides exist. This paper reviews the available literature on the post-fire inspection and evaluation of concrete tunnels. The effects of fire on concrete and steel are discussed, including loss of strength, thermal spalling of concrete, and loss of strength in the bond between concrete and steel. In addition, studies on the residual strength of concrete members are presented. Available post-fire inspection strategies and methods are also discussed. Finally, the results of a survey of post-fire tunnel inspection practices at state Departments of Transportation and transit organizations across the United States are presented. Several models available in both structural building codes and experimental studies allow for the estimation of residual concrete compressive and steel tensile strength after heating and cooling from a given temperature. Furthermore, a variety of post-fire assessment methods are available, which include methods to assess the general post-fire condition of concrete tunnels, as well as methods to more directly assess the residual condition of concrete. Lastly, the review of literature and the survey of United States transit organizations revealed a lack of existing post-fire inspection procedures for concrete tunnels, and a need for further research on the subject.

Hot Wind to the Body Can Facilitate Vection Only When Participants Walk Through a Fire Corridor Virtually

Vection has been reported to be enhanced by wind, as long as the wind is a normal temperature and not hot. However, here we report that a hot wind can facilitate vection, as long as it is natural and consistent with the visual stimulus. We created a fire-corridor stimulus that was consistent with a hot wind and a control stimulus composed of cubes, which were irrelevant to a hot wind. We compared the vection strength induced by a fire-corridor (fire condition) visual stimulus with that induced by geometric cubes (no-fire condition) visual stimulus. There were three wind type conditions: a normal temperature wind, hot wind, and no wind. The results showed that a normal temperature wind facilitated vection and that a hot wind (but not a normal wind) highly enhanced vection when a fire-corridor stimulus was presented. These results suggest that vection is highly affected and modulated by high-level cognitive processes.