Papers by Keyword: Masonry Tower

Abstract: Structural Health Monitoring (SHM) has a crucial role in the diagnosis and conservation of historical buildings, which are typically characterized by articulated fabrics, constructed over decades using different materials and construction techniques. All these issues lead to very complex structural behaviour whose reliable assessment cannot disregard from a sound interpretation of data from SHM systems. SHM systems can be classified into (i) static systems, monitoring the long term time evolutions of specific quantities (such as amplitude of cracks, inclination of walls, relative distances, etc.) and (ii) dynamic systems, continuously monitoring the dynamic response (velocities, accelerations) in order to gather information upon overall dynamic properties such as natural frequencies, mode shapes and damping ratios. The recorded raw data need to be processed in order to distinguish eventual evolutionary trends from the seasonal and daily variations related to thermal effects. In the present work, a simple unified approach for data interpretation acquired from both static and dynamic SHM systems installed in historical buildings is presented. The approach is aimed at: (i) introducing reference quantities for interpretation of seasonal and daily variations, (ii) providing order of magnitudes of reference quantities and (iii) identifying eventual evolutionary trends which could be related to the presence of potential structural criticalities. The approach is illustrated referring to the “Two Towers” of Bologna.

Abstract: Sequentially Linear Analysis (SLA) is an alternative method that avoids convergence problems derived from the use of classic nonlinear finite element analysis. Instead of using incremental iterative schemes (arc-length control, Newton-Raphson), SLA is a sequential procedure made by a series of linear analysis, able to capture nonlinear behavior, reducing Young Modulus, according to saw-tooth constitutive relation. In this paper an investigation above all the aspects of the methods will be presented using a new element suitable for the SLA: accuracy of the solutions and computational cost, i.e. the time needed to get to satisfactory conclusions of the analysis. In order to test the efficiency of the proposed element, numerical results hailed from different brittle problems, such as glass beam and an ideal masonry tower, are used.

Abstract: In the present article non-destructive testing evaluation of the existing damage evolution has been applied to some buildings of the medieval town of Craco (Matera, Italy) and, in particular, to the Normand tower. Actually the little town of Craco is totally abandoned as a consequence of the activation of the landslide motions of its soil depth. Nevertheless, the Normand tower still stands because it is located on a stable and stiffer foundation ground. The tower was built in the XII century. It is 20 m tall and has a symmetric square plan, with dimensions 11 m x 11 m; it was built for defense against enemy attacks. Inside the tower a cistern in reinforced concrete was placed in 1949. It is not connected to the structural walls of the tower; however it represents an obstacle for installing the damage detection equipment and sensors. In this article a preliminary study on the masonry structure of the Normand tower is carried on. A finite element numerical model has been developed and a modal analysis has been performed. The final aim of the research is to find out the evolutionary stage of the cracks and to propose a possible retrofit of the tower.

Abstract: This paper presents a case study of foundation of an inclined independent masonry tower in Angkor. One of the Prasat Sour Prat towers had been dismantled before reconstruction for conservation. The foundation was inclined as the same as the upper structure of the tower and spreading outwards. The inclination was considered caused by foundation failure with some differential settlements of the ground. During dismantling, the soil layers exposed on the trenched section were found rather horizontal than the inclined state that had been expected. Laterite blocks of step slope stones was found to have slid down along the soil mound of the foundation. The mechanism might have been caused by weakening of soil strength by wetting ground. Without dismantling, the real mechanism of the inclination was never known as well as the corresponding counter measures.