Indirect estimates of flexural strain in concrete sidewalks induced by vertical movement

This paper examines different numerical methods to estimate flexural strain from surface elevationmeasurements on concrete sidewalks. Surface elevations, along a typical concrete sidewalk cross section, weremonitored on a monthly basis as part of a study to determine the cracking mechanism of concrete sidewalks. These measurements were carried out in Calgary, Edmonton, and Camrose, Alberta, between 1993 and mid-1995. Finite difference, cubic spline, polynomial fit, and Fourier series methods of analyses are described for an indirect estimation of flexural strains in sidewalks. The sensitivity of these methods to measurement error is discussed. The Fourier series method is found to be the best procedure to analyse sidewalk surface elevation data for flexural strains estimates. The numerical methods to indirectly determine strain are best suited for those circumstances where installation of strain gauges is difficult, expensive, or impossible.Cet article examine diff\ue9rentes m\ue9thodes num\ue9riques pour estimer la contrainte de fl\ue9xion d'apr\ue8s desmesures d'\ue9l\ue9vations de surfaces de trottoirs en b\ue9ton. Le long d'une coupe transversale d'un trottoir en b\ue9ton typique, des \ue9l\ue9vataions de surfaces ont \ue9t\ue9 mesur\ue9es mensuellement pour contribuer \ue0 une \ue9tude visant \ue0 d\ue9terminer le mechanisme de fissuration de trottoires en b\ue9ton. Ces mesures ont \ue9t\ue9 prises \ue0 Calgary, Edmonton et Camrose de 1993 \ue0 mi-1995. Les m\ue9thodes d'analyses de diff\ue9rences finies, de spline cubique, de ajustement polynomial et de s\ue9ries de Fourier sont d\ue9crites pour une estimation indirecte de tensions de fl\ue9xion dans les trottoirs. La sensibilit\ue9 de ces m\ue9thodes \ue0 des erreures de mesures est discut\ue9e. Il a \ue9t\ue9 trouv\ue9 que la m\ue9thode de s\ue9ries de Fourrier \ue9tait la meilleure proc\ue9dure pour analyser des donn\ue9es d'\ue9levation de surface d'un trottoir pour estimer les tensions de fl\ue9xion. Les m\ue9thodes num\ue9riques pour d\ue9terminer la tension indirectement sont le plus appropri\ue9es lorsque l'installation de gauge de tension est difficile, co\ufbteuse ou impossible.Peer reviewed: YesNRC publication: Ye