Techniques for Processing Experimental Data for Structural Health Monitoring of Bridges

Reliability of transport artificial structures and transit of trains at sanctioned speed should be provided with the necessary and sufficient load-bearing capacity, strength, rigidity, and stability of engineering structures.The objective of this work was to substantiate the possibility of using well-known methods for controlling the stress-strain state of structures using automated systems of structural health monitoring of bridge spans.It is extremely important regarding operation of transport artificial structures designed according to the standards of the first half of the 20th century.Under these conditions, the experimental determination of the stress-strain state of bearing structures of bridges becomes the most important component of the task of a comprehensive assessment of physical wear and tear as well as of operational reliability of the structures. Monitoring the structural health and technical condition of bridges and planning of timely measures aimed at the repair, strengthening or reconstruction of spans will extend their service life and ensure safety during operation.Maximum permissible deflections of spans under a movable temporary vertical load have been revealed since to ensure smooth movement of vehicles it is necessary to control horizontal longitudinal and transverse displacements of the top of the bridge piers, as well as vertical settlements.The paper suggests methods of interpreting data measured by inclinometers and electric strain gauges, tensiometers to use them in an automated system for monitoring the structural health of railway bridges. The method of strain measurement is described in detail in the proposed options for installing resistance strain gauges on structures to measure tensile-compression stresses and longitudinal forces due to a temporary vertical load.Monitoring the technical condition of bridge structures, using the methods for measuring deflections and deformations proposed by the authors in this article, will make it possible to assess the change in bearing capacity of the structure over the entire period of operation. The study used regulations and experience of the Russian Federation and the Republic of Kazakhstan.

Enhanced Virtual Machine Placement in Cloud Data Centers: Combinations of Fuzzy Logic with Reinforcement Learning and Biogeography-Based Optimization (BBO) Algorithms

The process of mapping Virtual Machines (VMs) to Physical Ma- chines (PMs), which is defined as VM placement, affects Cloud Data Centers (DCs) performance. To enhance the performance, optimal placement of VMs regarding conflicting objectives has been proposed in some research, such as Multi-Objective VM reBalance (MOVMrB) and Reinforcement Learning VM reBalance (RLVMrB) in recent years. The MOVMrB algorithm is based on the BBO meta-heuristic algorithm and the RLVMrB algorithm inspired by reinforcement learning, which in both of them the non-dominance method is used to evaluate generated solutions. Although this approach reaches accept- able results, it fails to consider other solutions which are optimal regarding all objectives, when it meets the best solution based on one of these objectives. In this paper, we propose two enhanced multi-objective algorithms, Fuzzy- RLVMrB and Fuzzy-MOVMrB, that are able to consider all objectives when evaluating candidate solutions in solution space. All four algorithms aim to balance the load between VMs in terms of processor, bandwidth, and memory as well as horizontal and vertical load balance. We simulated all algorithms using the CloudSim simulator and compared them in terms of horizontal and vertical load balance and execution time. The simulation results show that Fuzzy-RLVMrB and Fuzzy-MOVMrB algorithms outperform RLVMrB and MOVMrB algorithms in terms of vertical load balancing and horizontal load balancing. Also, the RLVMrB and Fuzzy-RLVMrB algorithms are better in execution time than the MOVMrB and Fuzzy-MOVMrB algorithms.

Floating road construction on soft soil

The main problem of road construction on saturated soft soils is due to their low bearing capacity and large settlement. One of the solutions to such problems is to install piled box culverts-geofoam. In this study, the pile box culvert-geofoam was modelled as raft foundation. This experimental study was conducted by making a prototype raft file foundation gradually loaded with a maximum vertical load of 20 kN. Different thicknesses of geofoam were utilized in order to observe the influence of thickness on the settlement. Furthermore, difference in settlement is also found when the culvert was constructed with and without geofoam. Thicker geofoam was observed to result in smaller settlement.

Vertical Seismic Isolation Device for Three-Dimensional Seismic Isolation of Nuclear Power Plant Equipment—Case Study

The purpose of this study was to develop a vertical seismic isolation device essential for the three-dimensional seismic isolation design of nuclear power plant equipment. The vertical seismic isolation device in this study has a concept that can be integrally combined with a conventional laminated rubber bearing, a horizontal seismic isolator with a design vertical load of 10 kN. To develop the vertical seismic isolation device, the vertical spring and the seismic energy dissipation device capable of limiting the vertical displacement of the spring were designed and their performances were verified through actual tests. In this study, the target elevation of the floor is 136 ft, where safety-related nuclear equipment, such as cabinet and remote shutdown console, etc., is installed. The sensitivity studies were carried out to investigate the optimal design vertical isolation frequencies for the target building elevation. Based on the results of the sensitivity study, a disc spring and a helical coil spring were selected for the vertical stiffness design, and the steel damper was selected for the seismic energy dissipation, and their performance characteristics were tested to confirm the design performance. For the steel damper, three types were designed and their energy dissipation characteristics by hysteretic behavior were confirmed by the inelastic finite element analyses and the tests in static fully reversed cyclic conditions. Through the study of the vertical seismic isolation device, it was found that 2.5 Hz~3.0 Hz is appropriate for the optimal design vertical isolation. With results of the vertical seismic isolation performance analysis, the appropriate number of steel dampers are proposed to limit the vertical seismic displacement of the spring within the static displacement range by the design vertical load.

SEGMENT OF WALL PANEL FOR TIMBER STRUCTURES UNDER VERTICAL LOAD

The subject of this paper is an experimental and numerical analysis of the stability of the wall panels with one-side board sheathing for timber structures. The reinforcement of the panel is provided using glued timber composite I-shaped element consisting of a web made of a wood-based desk embedded into flanges of solid timber. The mechanism of the behaviour of these panels, mode of the failure and reliable procedure to determine the buckling load-bearing capacity not been fully explored so far. This work describes the behaviour of the wall panel under vertical load and the method of failure using experimental and numerical analysis. The reduction coefficient kJ was determined, which can be used for a simple calculation of the buckling capacity of a wall panel.

A TECHNIQUE OF PANELS CUTTING FOR MODIFICATION OF HULL GEOMETRY HYDRODYNAMIC MODELS

A panel cutting technique is developed for automatic modification of an initial mesh of a ship hull used for hydrodynamic computations leading to improved meshes for the prediction of wave induced vertical load effects. The technique can provide a model with divided panels in any defined position regardless of the initial discretization of the body. The applications of the provided technique include panel distinction and division in predetermined positions, generation of finer mesh based on the initial coarser model of meshes and improvement of vertical load prediction in predetermined positions. The method is applied for case studies of a barge, shuttle tanker and frigate to depict various applications. Finally, the hydrostatic and hydrodynamic vertical shear forces are calculated for two models of initial and modified panels of well-known frigate 5415. The results are compared for the sections alongside the ship and accuracy of load integration is shown for predetermined sections.

Bearing Characteristics of Diaphragm Wall Foundation under Vertical and Combined Load

To investigate the bearing characteristics of diaphragm wall foundation under combined load, the results from elasto-plastic analyses of 3D finite element models (FEM) were presented in this study. The vertical load of the diaphragm wall foundation is borne by inner and outer side resistance, resistance of soil core and the end of wall, respectively. Moreover, the sum of end resistance and soil core resistance accounts for about 75% of the vertical load. The mobilization mechanism and distribution of side resistance of the foundation were also analyzed. It is clarified that the mobilization characteristics of inner and outer side resistance of the wall are completely opposite. Due to the combined load, the horizontal load has an amplification effect on the settlement of the foundation. Additionally, the calculation methods of the Eight-component Winkler spring model and rigid pile displacement were used for determining the vertical load-bearing capacity and the overturning stability. A comparison between results from the FEM and the theoretical calculation methods showed that the results of the numerical simulation properly coincided with that of the displacement solution of theoretical model. The conclusions obtained by the above methods all indicate that the foundation has the characteristics of overall overturning failure under the combined load.