Soil–steel structure shell displacement functions based on tensometric measurements

Abstract

This paper analyses the effects of loads that change their location, i.e. moving but quasi-static loads. Displacements defining the deformation of the soil–steel structure’s shell buried in soil are calculated from the results of measurements performed using a dense grid of points located on the circumferential section of the corrugated plate. In this way, all the components of the structure, namely the corrugated plate, the backfill and the pavement with its foundation, as well as the natural (real) principles of their interaction, are taken into account in the solution. In the proposed algorithm, unit strains are converted into displacements, whereby results as accurate as the ones obtained by direct experimental measurements are obtained. The algorithm’s main advantages are that the number of points is limitless, they are regularly distributed on the circumferential section of the shell and any displacement directions can be obtained. Consequently, the deformations of the shell can be faithfully reproduced. The algorithm’s convenient feature is that one can use a simplified computational diagram of the shell in the form of a beam having the shape of the shell in 2D space (without the other components of the soil–steel structure). The advantage of this measuring method (electric resistance tensometry) is that there is no need to build the solid scaffold used for displacement measurements. The research focuses on the analysis of the displacements and the unit strains arising during the primary and secondary (return) travel of the load.

Effects of Surrounding Earth on Shell During the Construction of Flexible Bridge Structures

“…In soil-steel structure models, one can distinguish two structural subsystems: [4,8] the backfill plus the pavement with its foundation, and the shell. As a computational model of the soil-steel structure during its service life, a 3D model is used.…”

“…If unit strains in two points of a corrugation, as in the cross section of the bar shown in Fig. 3, are to be calculated, then using axial forces n and bending moments m, one can formulate the following two equations for the corrugation crest: [8] (1) and for the corrugation valley: (2) where v g and v D are the distances of the points from the axis of inertia. In order to determine the unit strains in any shell point, tensometric measurements are performed using the configuration of measuring points, as shown in Fig.…”

“…3, located on the plate's surface accessible from the inside. Under the assumption of Bernoulli's principle concerning planar cross sections, using a twin set of strain gauge sensors, one can determine the strains along the axis of inertia of the corrugated plate cross section from the relation: [8] (3)…”

“…and 9EA/a and EI/a in formulas (8) and 9are the rigidities of a shell zone with corrugation length a, while ds is a differentially small segment of the perimeter zone of the shell arc. In this paper, the shell's upper part, where the curvature radius amounts to R, is analysed.…”

“…Usually a regular configuration of measuring points, as shown in Fig. 5, is used to determine the interfacial interactions, whereby differential equations (8) and (9) can be replaced with difference relations. From the dependence between internal static forces n(s) and m(s), expressed as a function relative to the axis (s) running along the perimeter zone of the shell, as in Fig.…”