Capacity interaction in brick masonry under simultaneous in-plane and out-of-plane loads

A considerable number of numerical and experimental studies, carried out to-date to investigate the behaviour of masonry walls under seismic loading, have considered the in-plane or the out-of-plane response of the wall separately without due consideration for any possible interaction between the two responses. In this paper, the results of a series of tests with different levels of simultaneous in-plane shear and out-of-plane bending actions on small brick walls are presented. The tests results indicate noticeable interaction between the in-plane shear and out-of-plane bending strengths of brick walls. Test results are also used to validate representing numerical models of wall panels. The combined in-plane/out-of-plane capacity interaction in full-scale walls having different aspect ratios is then investigated using these numerical models. It is found that the wall aspect ratio highly influences the interaction level, which must be considered in masonry design

Definition of interaction curves for the in-plane and out-of-plane capacity in brick masonry walls

During an earthquake a wall is subjected to a three dimensional acceleration field and undergoes simultaneous in-plane and out-of-plane loading. The action of one type of loading on the wall affects the strength of the wall against another type of loading. In this paper, a numerical investigation, supported by experiments, is conducted aimed at deriving appropriate relations for the in-plane/out-of-plane capacity interaction in unreinforced brick walls. Through a comprehensive parametric study, the main affecting parameters are recognized and their influences on the capacity interaction are established. The parametric study indicates that the aspect ratio of the wall and the elastic and inelastic material properties in tension have the most influence on the level of the in-plane and out-of-plane capacity interaction in masonry walls. Based on the results of these investigations, representing empirical analytical relations for evaluating the interaction are derived and their accuracy is verified

In-plane strength of masonry wall panels: A comparison between design codes and high-fidelity models

The susceptibility of masonry structures subjected to in-plane loads is determined by the failure mechanisms that might occur, which are governed by the material and geometric properties of the masonry. In practice, masonry walls are usually analysed using design codes, which are derived from analytical (code-based) methods. However, design codes may be overly simplistic and conservative, necessitating re-evaluation and modifications. This paper aims to compile and review various existing design codes for determining the in-plane strength of masonry walls and assess their validity when predicting masonry wall panels’ in-plane strength with different geometry and material properties. For this purpose, Monte Carlo simulations were used to vary the geometric and material properties of walls and understand how these affect their in-plane strength and failure mode. An extensive numerical investigation employing three-dimensional finite element (FE) analysis was also undertaken to better understand the influence of pre-compression, wall height to length ratio, and aspect ratio of masonry units on the in-plane force capacity of the masonry walls. First, a cyclic quasi-static test was utilized to validate the numerical model. The results from the numerical analysis were in good agreement with the experimental findings in terms of load vs drift curve and damage pattern. Following that, the numerical model was used to implement a parametric investigation. According to the findings, in-plane strength decreases as the aspect ratio of the wall increases. Pre-compression also influences the in-plane strength of the masonry wall and the brittleness of the failure. In-plane strength of the shear-controlled walls was higher than that of flexure-controlled walls. Failure mechanisms of walls were also extensively studied and a combination of failure mechanisms was observed. Also, the aspect ratio of masonry units was found to influence the failure mechanism of the wall. The comparison of the estimated strength and failure mode of the walls using the code formulations with those obtained from the numerical study indicates that in some cases (particularly the squat walls and shear-controlled walls) the codes did not predict the behaviour of the wall panels satisfactorily. This may be attributed to the multiple governing modes of failure in real cases, while the code formulations only consider a particular failure mode. The findings presented here highlight the need for updated design codes

ON THE IN-PLANE FLEXURAL RESPONSE OF CANTILEVER UNREINFORCED CLAY BRICKWORK MASONRY WALL PANELS

This paper studies the in-plane response of unreinforced clay brickwork masonry wall panels. For this purpose, a non-linear three-dimensional heterogenous Finite Element (FE) model was developed using ABAQUS software. The model was validated against experimental studies obtained from the literature. Then, a parametric study was undertaken to investigate the effects of a) pre-compression, b) Height to Length ratio (H/L) of the wall and c) H/L of the masonry units on the in-plane strength, initial stiffness, peak drift and ultimate drift limit. Finally, results obtained from the FE computational models compared against those obtained from design codes (Eurocode) for determining the in-plane force capacity and drift capacity of the URM walls. From the analysis of results it was found that in most cases, Eurocode overestimates the ultimate drift ratio when compared to the findings from the FE analyses

L’«Avventuale fiorentino» di Giordano da Pisa

In this paper, a parametric study has been carried out on reinforced concrete (RC) exterior beam-column joints without transverse reinforcement in the joint region. This type of joints belongs to a group of RC structures classified as non-ductile RC buildings. In the previous investigations, special attention is paid to the joint aspect ratio and beam longitudinal reinforcement ratio. These parameters have been shown by other researchers to govern the joint shear behavior, although the degree of influence was not scrutinized to the degree required. The results of the current study confirmed once again that these parameters have a significant influence on the shear failure in RC joints. Apart from that, the degree of influence has been quantified in great detail. The findings suggest that the correct selection of these parameters is extremely important in the design of RC buildings, and a wrong choice may adversely affect the behavior