The impact of heavy object on an underground structure when falling onto the ground surface

At the objects of space infrastructure and at nuclear power facilities there are industrial structures, the main task of which is to protect a person, equipment or machinery from emergencies such as, for example, explosions, falling of various objects, fragments. In accordance with the requirements of the Federal Law On the Protection of the Population and Territories from Natural and Technogenic Emergencies, when calculating such structures, all types of loads corresponding to their functional purpose must be taken into account. So, for structures located in the area of a possible accident and the fall of space rockets, it is necessary to calculate for the fall of the destroyed parts of the rocket engine. For nuclear power plant facilities, such accidents occur when containers and other heavy objects fall on the ground, affecting underground structures located in the ground, and for civil defense protective structures built into the basement floors of buildings, it is necessary to consider situations in which the overlying floors of a building collapse when exposed to there is an air shock wave on them. Therefore, this problem is relevant, and in this study, a finite-element method for calculating an underground structure in a non-linear dynamic setting has been developed when a large overall object collides with the ground.

COMPARATIVE STUDY OF THE REINFORCED STEEL BARS OBTAINED FROM A FAILED RESIDENTIAL BUILDING AND THE SHELVES

Nigeria is a developing nation, the need to build structures is on high rise. The rate of structure failure and building collapse is also on the rise. This paper presents a comparative study on Mechanical Properties of Reinforced steel bars obtained from the shelves, and that obtained from the failed structure of a residential building which is then compared to International standard NO-432 . Steels are main reinforcing materials for most structural buildings, but when the integrity is compromised, it leads to devastating consequences. The quality of concrete and steel reinforcement must be such that has appropriate yield strength so that the structure can sustain the require load within the required time interval. The Ultimate Tensile Strength and percentage elongation of the steel bars obtained from the two sources were investigated. One of the sources was a reinforcing bar used in Millennium Estate, Mary Land, Lagos State, Nigeria. The steel bar samples of sizes 10mm and 16mm diameter were subjected to mechanical testing using a universal testing machine. The percentage elongation met with the standards while the 16mm samples are below the standards for both the failed structure and shelves.

The Working Conditions and Optimisation of a Large Rainwater Harvesting and Treatment System in an Area at a Risk of Erosion

Rainwater harvesting and treatment systems (RHTS) are used in many places around the world as a part of sustainable water management. They decrease the risk of overloading the sewage network and environmental pollution. The efficiency and reasonableness of using such solutions in specific erosive conditions are not sufficiently understood. The aim of the study was to evaluate the operation of RHTS, receiving effluents from the wholesale market and fuel station (twenty years of observations). The studied system is located in an area endangered by water erosion. In the study period, due to the accumulation of erosive phenomena, it was necessary to optimise the system (including the installation of new devices and increasing the capacity of reservoirs). The analyses referred to the stability and work safety of the most important equipment and water treatment efficiency. The quality of water in the reservoirs was measured before and after the modernisation of the system. Selected physical, oxygen, biogenic and salinity indicators were determined in the water. During the study, RHTS had a positive effect on the quality of rainwater runoff – the values of many contaminants were reduced (RHTS 1: suspended solids, nitrogen, iron, potassium; RHTS 2: conductivity, suspended solids, nitrogen). Design and operational errors were noticed that in the long run may contribute to deteriorating the operational efficiency and even lead to a building collapse (intense erosive phenomena). This study clearly demonstrates that building a rainwater management system is a highly site-specific issue.

A preliminary analysis and discussion of the condominium building collapse in surfside, Florida, US, June 24, 2021

On June 24, 2021, a 40-year-old reinforced concrete flat plate structure building in Miami suffered a sudden partial collapse. This study analyzed the overall performance and key components of the collapsed building based on the building design codes (ACI-318 and GB 50010). Punching shear and post-punching performances of typical slab-column joints are also studied through the refined finite element analysis. The collapse process was simulated and visualized using a physics engine. By way of these analyses, weak design points of the collapsed building are highlighted. The differences between the reinforcement detailing of the collapsed building and the requirements of the current Chinese code are discussed, together with a comparison of the punching shear and post-punching performances. The simulated collapse procedure and debris distribution are compared with the actual collapse scenes.