Stress-strain state of damaged reinforced concrete bended elements at operational load level

Each structure is exposed to different influences during operation. As a result, there are various defects and damages of these elements that affect their safe operation. The article presents the results of experimental studies of reinforced concrete beams with damages to stretched reinforcement made with and without initial load application. As the damages were accepted one or five Ø5.6 mm holes. In one case, the damage was made until the beam destruction (up to the 8.4 mm opening) Control samples of both series were destroyed due to crushing of the compressed zone of concrete. Samples that were damaged without initial loading collapsed due to rupture of the stretched reinforcement. The same type of failure was identified for damages at the operational load level.

Application of Operational Load Monitoring System for Fatigue Estimation of Main Landing Gear Attachment Frame of an Aircraft

In this paper, we present an approach to fatigue estimation of a Main Landing Gear (MLG) attachment frame due to vertical landing forces based on Operational Loads Monitoring (OLM) system records. In particular, the impact of different phases of landing and on ground operations and fatigue wear of the MLG frame is analyzed. The main functionality of the developed OLM system is the individual assessment of fatigue of the main landing gear node structure for Su-22UM3K aircraft due to standard and Touch-And-Go (T&G) landings. Furthermore, the system allows for assessment of stress cumulation in the main landing gear node structure during touchdown and allows for detection of hard landings. Determination of selected stages of flight, classification of different types of load cycles of the structure recorded by strain gauge sensors during standard full stop landings and taxiing are also implemented in the developed system. Based on those capabilities, it is possible to monitor and compare equivalents of landing fatigue wear between airplanes and landing fatigue wear across all flights of a given airplane, which can be incorporated into fleet management paradigms for the purpose of optimal maintenance of aircraft. In this article, a detailed description of the system and algorithms used for landing gear node fatigue assessment is provided, and the results obtained during the 3-year period of system operation for the fleet of six aircraft are delivered and discussed.

Strength Analysis of a Two-Layer PETF-Concrete Column with Allowance for Contact Interaction between Layers

This article develops an idea of mechanical recycling of polymer wastes. Unlike previous research studies, which are dedicated to the study of the physical and mechanical properties of fibrous concrete and the technology of its manufacturing, this work considers a specific construction product—laminated concrete column made of recycled polyethylene terephthalate (PETF). Currently, there are no policy documents (standards or codes) regarding the engineering design of such constructions. Therefore, the authors’ attention is focused on mechanical and mathematical modeling of the laminated column behavior under operational load. An analytical study of two-layer PETF-concrete column’s stress-strain state was performed, taking into account the contact interaction between inhomogeneous layers of the materials. It has been determined that, in certain circumstances, the contact pressure between the layers can have a significant effect on the load-bearing capacity of the column. In general, a method of engineering assessment of laminated columns’ load-bearing capacity was developed.

Marine main engine speed of rotation energy-saving control solution based on artificial neural network application

During operation and maintenance marine main engine is subjected to great variety of different impacts: climatic, operational, load impacts and others. Thus, object efficiency, being directly dependant on impacts overcome ability is known to be able to affect the major part of financial costs, related to the marine transport processes. Therefore, the marine shipping efficiency provision goal can be stated as vessel main engine propulsion plant reliability and operational condition maintenance together with external impacts influences minimization. One of the most significant marine propulsion plant influences is known to be sea water surface swell. However, it is known to be complicated in measurement as it requires some number of complicated devices to be installed outside the ships’ hull. Such impacts are known to significantly affect object efficiency, leading to the list of undesirable results, such as speed of rotation fluctuations, increased fuel consumptions, increased vibrations and so on. This article gives an overview of one of the methods of combating significant speed of rotation fluctuations whilst ship rough sea navigation. The suggested algorithm is based on neural network structure integration as well as fuzzy logic controller integration into additional speed of rotation control system feedback link and can save up to 53,5 thousands of USD per year for the ship owner.

Assessment of the parameters of the rapid response of fire and rescue units depending on the time of day

Introduction. The change in the speed of the fire and rescue subdivisions to the place of call, depending on the time of day, is studied. The study is related to the determination of the locations of fire departments. Goals and objectives. The study of the parameters of the rapid response of fire and rescue units was carried out. For cities of the Russian Federation with a population of more than 1 million inhabitants of the Russian Federation for the period 2019-2021, statistical distributions by hours of the day of the number of trips to fires of fire and rescue units, the speed of mobile vehicles, the time of travel to the place of call are constructed. The share of departures for which the arrival time of the first fire and rescue unit exceeds the standard value established by Federal Law of July 22, 2008 No. 123-FZ is determined. Results and discussion. As a result of the study, it was revealed that the maximum value of the speed of following fire and rescue units is observed in the daytime from 10 to 15 hours - 34 km/h, the minimum value is reached at night during the period from 1 to 3 hours - 31 km/h. A study of the parameters of the functioning of fire and rescue units in cities with a population of more than 1 million inhabitants showed that the operational load on fire and rescue units in the daytime increases significantly, which can lead to an adjustment of the plan for attracting forces and resources, when, when a call is received, the guard on duty will be already busy serving another call. These circumstances lead to an increase in the travel time of fire and rescue divisions. As a result, the share of calls for which 123-FZ norms are not met is increasing. The share of such trips during the daytime increases to 18 % versus 8-10 % at night. Conclusions. When determining the locations of fire and rescue units, it is necessary to take into account peak loads that occur during the day. Keywords: fire and rescue subdivisions, speed of following, time of following, area of normative service, composition of forces and means

Stress-Strain State of Reinforced Concrete Overpass under Load

Beam spans are the most vulnerable elements of the bridge system, as they are exposed to direct effects of mobile load, environmental and climatic factors (temperature and humidity effects, including freezing and thawing, shrinkage, humidity, etc.). Appearance of defects of the structure is inevitable; the refore civil engineers face a topical problem of strengthening of damaged structures of bridges. The article discusses some results of calculated values and instrumental measurements of stress-strain state (SSS) of reinforced concrete beam span structures of railway overpass under operational load caused by different rolling stock units. The objective of this study is to control stress-strain state of railway overpass for identification and elimination of defects at early stages. The calculation results obtained, carried out by finite-element method (FEM) in the program ABAQUS/Standard correlate well with experimental data. These results can be used for monitoring the state of artificial structures on main lines of JSC NC KTZ.