Institute of Fundamental Technological Research

This paper presents the effects of changes in temperature and moisture content on the dynamic properties of semi-circular arches made of clay brick and gypsum mortar constructed and tested in the laboratory. First, the mechanical properties of the materials used were determined by experimental tests. Operational Modal Analysis was then performed for each condition to measure natural frequencies, mode shapes, and modal damping ratios. An empirical equation for estimating the natural frequencies of the studied arch at different material moisture contents was proposed using the obtained results from experimental tests. Finally, the Finite Element Model Updating Method (FEMU) was applied to calibrate some of the material mechanical properties in modelled arches. In contrast to the effect of moisture, temperature changes showed a difficulty to interpret effect on the dynamic properties of the arch. On the other hand, Poisson's ratio did not affect the dynamic behaviour of the specimen.

Operational Modal Analysis, Brick Masonry Semi-Circular Arch, Temperature, Moisture, Dynamic Parameters

In this paper, several parametric studies were performed on the dynamic behaviour of seven types of Persian brick masonry arches using the finite element method. The studied parameters included the arch types, arch thickness, arch scale, support conditions, and brick arrangement. The finite element models were calibrated using experimental results obtained from operational modal analysis of an arch constructed in the laboratory. The parametric studies have shown that the type of arch significantly affects the natural frequencies. The increasing of arch thickness leads to increase of the natural frequencies. Simply supported arches exhibit reduced natural frequencies, compared to those fixed at their supports. Brick arrangement has little effect on the natural frequency. Finally, an empirical equation for estimating the fundamental frequency of the studied arches was proposed using the obtained results from finite element models. The high accuracy of the empirical equation was tested through measurements on a real full-scale arch.

Geometric Parameters, Natural Frequencies, Brick Arrangement, Support Conditions, Persian Brick Masonry Arches

In this paper, the dynamic properties of three types of Persian brick masonry arches, semi-circular, ordinary pointed and ordinary four-centred have been studied. These arches were constructed with clay brick, and gypsum mortar in the laboratory and experimental tests were conducted. First, the mechanical properties of the used materials were determined. Then, operational modal analysis was used to measure the dynamic properties of the constructed arches. Afterwards, a horizontal displacement was applied to the arch support to create a crack. The arches were repaired then, and dynamic identification was performed for each case. Several damage detection methods were used to evaluate their ability to detect damage in brick masonry arches. Finite element model updating was used to track changes in the material properties of arches and to match numerical results with dynamic laboratory results. The study showed that damage has a significant effect on the dynamic properties of arches. Repairing the damage partially restores the dynamic parameters to the undamaged condition, but it cannot completely transform the arch into an arch without damage. Damage detection methods were able to identify the occurrence of damage to the arches, but there are limitations in the use of these methods. Diagrams were generated to estimate the static moduli of brick and of gypsum mortar from the dynamic modulus of elasticity of the assemblage of brick and gypsum mortar.