Sarah Petry

Cyclic test data of six unreinforced masonry walls with different boundary conditions

Previous test data on unreinforced masonry walls focused on the global response of the wall. A new data set (Petry and Beyer 2014a; DOI:10.5281/zenodo.8443) on six wall tests, which is publicly available, allows for linking global to local deformations of masonry walls, which can be useful for advancing performance-based design and assessment methods for unreinforced masonry buildings. This data paper presents the results of a test series on six identical unreinforced masonry walls that were constructed using hollow clay brick units and standard cement-based mortar. The test units were subjected to quasi-static cycles of increasing drift demands and the tests differed with regard to the applied axial load and the moment restraint applied at the top of the walls. The walls were tested up to failure. Throughout the loading the deformations of the walls were recorded using a digital photogrammetric measurement system tracking the movement of 312 points per test unit.

Scaling unreinforced masonry for reduced-scale seismic testing

When testing multi-storey structures, most testing facilities require the testing of a reduced-scale model. A literature review on tests of scaled masonry structural components revealed that scaling of masonry was rather challenging and often significant differences in stiffness, strength and failure mechanisms between the different sized masonry were reported. This paper addresses the scaling of hollow clay brick masonry with fully mortared head and bed joints. We investigate different choices of scaling brick units and mortar joints. Based on the results of an extensive test programme including standard material tests and quasi-static cyclic tests on masonry walls subjected to horizontal and axial loads, we formulate recommendations for the production of a half-scale model of unreinforced masonry structures. The experimental results show a good match between full-scale and half-scale masonry. We discuss the differences in material properties that remained and compare the force-displacement hystereses obtained for the wall tests.

Limit states of modern unreinforced clay brick masonry walls subjected to in-plane loading

Recent research showed that the in-plane horizontal displacement capacity of unreinforced masonry (URM) walls depends on numerous factors that are not yet captured by current empirical drift capacity models; e.g., axial stress, shear span, geometry of the walls and the material used. In order to improve the performance-based assessment of URM wall buildings, future research should aim at developing numerical and mechanical models that link the global force-displacement response of URM walls to local deformation measures such as strains. This paper addresses the behaviour of modern clay brick masonry and makes first contributions to such an endeavour by the evaluation of experimental results: first, two sets of limit states are proposed that link local damage limit states to characteristic points of the global force-displacement response of the URM wall. The two sets define limit states for walls developing a shear or a flexural mechanism respectively. Second, local deformation measures deemed suitable for the characterisation of these limit states are evaluated from optical measurement data of quasi-static cyclic wall tests. These include strains, compression zone depth and the ratio of shear to flexural deformations.

Dynamic testing of a four-storey building with reinforced concrete and unreinforced masonry walls: Prediction, test results and data set

AbstractThis paper presents the results of a series of shake-table tests on a half-scale, four-storey building with reinforced concrete and unreinforced masonry walls. Due to the lack of reference tests, the seismic behaviour of such mixed structures is poorly understood. The test unit was subjected to several runs of increasing intensity yielding performance states between minor damage and near collapse. Before the test, the expected peak table accelerations leading to different limit states were estimated using the capacity spectrum method, and the predicted values corresponded rather well to actual sustained accelerations. Next to these analyses, the paper describes the test unit, instrumentation and input motion, and comments on the response of the mixed structure in terms of damage evolution and global response quantities, such as force–displacement response and drift and acceleration profiles. The raw and post-processed data sets are made publically available, and all relevant information with regard to data organisation and post-processing procedure is described in an appendix to this paper. The test serves therefore as a benchmark for the validation of numerical models of such mixed structures. The project aims at providing a foundation for the development of seismic design and assessment methods of mixed structures, which are currently not covered by structural codes, including Eurocode 8.

Towards displacement-based seismic design of modern unreinforced masonry structures

Unreinforced masonry (URM) structures are known to be rather vulnerable to seismic loading. Modern URM buildings with reinforced concrete (RC) slabs might, however, have an acceptable seismic performance for regions of low to moderate seismicity. In particular in countries of moderate seismicity it is often difficult to demonstrate the seismic safety of modern URM buildings by means of force-based design methods. Displacement-based design methods are known to lead to more realistic and less conservative results, opening up hence new opportunities for the use of structural masonry. An effective implementation of displacement-based design approaches requires reliable estimates of the structure’s force and displacement capacity. This paper contributes to this endeavour by taking a fresh look at the drift capacity of URM walls with hollow clay bricks and mortar joints of normal thickness. It discusses in particular the influence of the size of the test unit and the applied loading history and loading velocity on the drift capacities of URM walls.

Shake Table Testing of a Half-Scaled RC-URM Wall Structure

With the introduction of higher seismic design forces in the Swiss loading standard of 2003 most unreinforced masonry (URM) buildings fail to satisfy the seismic design check. For this reason, in new construction projects, a number of URM walls are nowadays replaced by reinforced concrete (RC) walls. The lateral bracing system of the resulting structure consists therefore of URM walls and some RC walls which are coupled by RC slabs and masonry spandrels. The same situation characterises a number of seismically retrofitted URM building across Europe in which RC walls are added to the original structure to improve its seismic behaviour. Within the framework of the FP7-SERIES project, a four-storey RC-URM wall structure was tested on the shake table at the EUCENTRE TREES Laboratory (Laboratory for Training and Research in Earthquake Engineering and Engineering Seismology) in Pavia (Italy). The test was conducted at half-scale and is part of a larger research initiative on mixed RC-URM wall systems initiated at EPFL (Ecole Polytechnique Federale de Lausanne, Switzerland). The key objective of the testing campaign was to gain insight into the dynamic behaviour of mixed RC-URM wall structures and to provide input for the definition of a performance-based design approach of such mixed structural system. Multiple shaking at increasing intensity was used to test the dynamic behaviour of the examined building. During the final shaking several of the URM walls lost their axial load bearing capacity, however, the structure did not collapse as it was subjected to uni-directional loading only and the axial load was transferred to the RC walls and the URM walls that were loaded out-of-plane. Random noise vibration tests were performed to monitor the elongation of the natural periods induced by the damage progression. The paper presents details on the structural system and the selected ground motion, the test set-up and the instrumentation. Additionally, initial results of the shake table test are presented with a first interpretation of the observed structural behaviour.