Dry Masonry Structures Research Articles

Approaches to strongly local phenomena in dry masonry structures

Approaches to strongly local phenomena in dry masonry structures

Approaches to strongly local phenomena in dry masonry structures

Sliding collapse tests performed on dry-stack masonry structures show a statistical dispersion in the results that cannot be explained by the dispersion in the properties of its constituent materials, but may correspond to an uneven distribution of stresses at the contact surfaces or within the constituent elements. In order to study these local phenomena, a method of numerical analysis of rigid blocks in unilateral contact is implemented and confronted with two types of benchmark tests: load tests and photoelastic tests. Comparing the results will allow stating that the random irregularities in contact surfaces play an important role in local behaviour. The results are very encouraging and suggest that this type of approach, common in the field of granular media but not in orthotropic media, can provide interesting insights for the analysis of local phenomena in historical masonry structures.

A FUNDAMENTAL STUDY ON APPLICABILITY OF DISCONTINUOUS DEFORMATION ANALYSIS TO MASONRY ARCHITECTURE

In this paper, we study on the applicability of Discontinuous Deformation Analysis (DDA) to dry-masonry structures such as Angkor. Many parameters are needed for DDA and we used contact force as a precision index to set guidelines for some parameters, i.e. close-line setting inside of a block, penalty spring constant, and time step increment. We also measured predominant frequency of block systems composed of different number of blocks and simulated them by DDA. We found that a system of different number of blocks requires different penalty spring constant. With these fundamental studies, we are elucidating collapse mechanism of dry-masonry structures.

FEM modeling of the towers in Bayon temple in Cambodia based on micro-tremor measurements

Bayon temple, Angkor, Cambodia, built in 13th century, is a dry-masonry temple made of sandstone which has deteriorated possibly due to rain, plants, settlements, and so on. Moreover, we may add wind induced direct or via-ground vibration to the list of deterioration causes since strong winds of more than 20 m/s was observed, which will require us to evaluate structural responses to the wind excitation. Based on micro-tremor measurements, we identified predominant frequencies, damping factors and base-fixed frequencies of the main tower and sub-towers in the temple and neighboring Prasat Sour Prat towers; FEM models were constructed by simulating the base-fixed natural frequencies of the horizontal translational modes. During the simulation, we had to reduce the elastic modulus of sandstone to less than 1/10 of typical value, which may suggest that the continuum modeling of dry-masonry structures is inappropriate.

Experimental And Numerical Investigation OfThe Sliding Behaviour Of A Set Of Two RigidBlocks Subjected To Cyclic Shear-type Loads

The aim of this paper is to study the shear transfer mechanism through the horizontal contact surface of two rigid blocks. The shear resistance offered by this contact interface is the main mechanism mobilized by the structural elements of many ancient stone dry-masonry structures in order to transfer horizontal actions from earthquakes and wind forces to the foundation. In some cases a certain connection exists between two blocks at the contact surface, which is materialized by wooden or metal parts at the central area of the blocks (poles, empolia). The role of this connection in transferring horizontal forces and its influence on the seismic behaviour is a point long debated by the research community. Cyclic experiments were performed at the laboratory of Strength of Materials and Structures of Aristotle University of Thessaloniki-Greece in order to study this sliding behaviour at the interface between two rigid blocks. The experimental sequence under investigation can be divided into two groups. The first group includes specimens without any connection between the rigid blocks, while the second group includes specimens with poles and empolia connecting the rigid blocks. During all tests the imposed cyclic horizontal sliding displacement was combined with constant level of vertical load applied at the top of the upper block. Through this experimental process, it became possible to describe the shear transfer mechanism through diagrams of horizontal sliding displacement versus horizontal load, and study the effects on the shear transfer behaviour between these rigid blocks without or with the connection with poles and empolia between them. Numerical finite element simulations of this shear transfer mechanism were also performed utilizing two commercial Finite Element Software packages.