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This document aims to give additional contribution into the study of tabique walls, a light timber wall existing in the old constructions in Portugal, and for which there is still a lack of information. This work includes an inspection campaign on 11 buildings located at the historic centre of the Portuguese city of Viseu. The information obtained allowed to create databases of the constituent elements and of the constructive details of these traditional timber walls, which may give guidance to understand the overall behaviour of these elements. Moreover, the collection of samples of timber, mortar and metallic connectors allowed carrying out laboratory tests to determine their physical and mechanical properties, contributing to a better global knowledge of tabique walls.

It is remarkable, the recent advances concerning the development of numerical modeling frameworks to simulate the infill panels’ seismic behavior. However, there is a lack of experimental data of their mechanical properties, which are of full importance to calibrate the numerical models. The primary objective of this paper is to present an extensive experimental campaign of mechanical characterization tests of infill masonry walls made with three different types of masonry units: lightweight vertical hollow concrete blocks and hollow clay bricks. Four different types of experimental tests were carried out, namely: compression strength tests, diagonal tensile strength tests, and flexural strength tests parallel and perpendicular to the horizontal bed joints. A total amount of 80 tests were carried out and are reported in the present paper. The second objective of this study was to compare the mechanical properties of as-built and existing infill walls. The results presented and discussed herein, will be in terms of strain-stress curves and damages observed within the tests. It was observed a fragile behavior in the panels made with hollow clay horizontal bricks, without propagation of cracks. The plaster increased the flexural strength by 57%.

The study of the reinforced concrete (RC) columns’ response to horizontal loads is of full importance to understand how earthquakes affect the integrity of structures, essentially those already built and especially vulnerable to this type of action, as is the case with many existing buildings on significant seismic activity zones which are not adequately prepared for that eventuality. Consequently, there is also the need to perform a significant number of experimental and numerical studies to understand how much the columns resistance is affected by the horizontal loading path combined with axial load. The present study focus on the comparison between the RC columns response when subjected to uniaxial and biaxial loading through a literature review of the experimental test data results. Additionally, a parametric study was performed to analyze the load-path influence in the columns response. Non-linear static pushover analysis were performed in more than 36 columns with different cross-sections, reinforcement ratios and axial load ratio, performing a total of 1300 analysis. The numerical results will be presented in terms of capacity curves, maximum strength comparison between the uniaxial and the biaxial response and several ratios were also determined to a do a better comparison.

Purpose: The infill masonry walls in recent worldwide earthquakes have shown that it is necessary to conduct further studies to characterize the behavior of existing buildings and, in particular, of infill masonry walls under seismic activity. The lack of characterization studies of infill walls made by concrete blocks justifies the investigation reported herein, which includes experimental tests on sample sets to evaluate the mechanical properties of masonry components (units and mortar) and assemblages (wallets) made with masonry units from Faial. For the later, normal compressive, diagonal tensile/shear and out-of-plane flexural strengths were obtained according to standard procedures, the results of which are presented in the manuscript. The paper aims to discuss these issues. Design/methodology/approach: One experimental campaign was conducted with the aim to mechanically characterize concrete blocks masonry samples. Several experimental tests were carried out in full-scale masonry concrete wallets according to the constructive methodology used. Findings: Based on the data obtained from the mechanical characterization tests of the concrete masonry blocks, it can be seen that under simple compression, the masonry specimens’ average resistance is about 6 times superior than the average resistance to diagonal shear/tension, while the stiffness is almost doubled. In simple compression tests, it was observed that the masonry specimens cracked in areas of higher drilling of the blocks. In the tensile tests by diagonal compression, it was found that the test specimens were mainly fissured by the block/mortar joint interfaces, following the delineation of settlement and top joints. Originality/value: There are no experimental results available in the literature for this type of bricks that can contribute to the development of numerical studies.

This paper focuses on the experience of the Rehabilitation Nucleus of the Construction Institute (NR-IC), integrated in the Faculty of Engineering of the University of Porto (FEUP) in the analysis, inspection, and diagnosis of structures with ancient defensive walls existing in Portugal. Aiming at promoting careful and heritage-respecting rehabilitation interventions, in line with the recommendations of ICOMOS (International Council on Monuments and Sites), the NR-IC has participated in several conservation and requalification projects. The development and implementation of a consolidated and holistic methodology of inspection and diagnosis aims to intervene in these historic structures by respecting their authenticity and integrity. In this context, this paper addresses two cases studies in different contexts and state of conservation: the Penedono Castle, in the countryside, and the Peniche Fortress in the sea shore.

During an earthquake, the reinforced concrete (RC) structures are subjected to deformations that may lead their structural elements to exceed the corresponding resistance limit state, forcing them to have nonlinear responses. The application of realistic numerical models that can represent the non-linearity of each structural element requires full examination and calibration. Furthermore, simplified numerical approaches that can represent the seismic behaviour of original and strengthened RC elements are of full importance. For this, the experimental tests are useful to calibrate the numerical models, and thus to capture as well as possible the real response of the elements. The main goal of this work is to evaluate the efficiency of a simplified numerical approach to represent strengthened RC columns with steel and CFRP jacketing, subjected to biaxial horizontal loading. The numerical modelling efficiency will be evaluated by comparing the numerical results with the experimental ones in terms of shear-drift hysteretic behaviour, initial stiffness and stiffness degradation, maximum strength and energy dissipation. The results shows a good performance of the numerical models, mainly for the RC columns strengthened with CFRP jacketing technique.

Recent earthquakes showed that the vulnerability of some RC buildings with masonry infill walls is high when subjected to seismic actions. During the design practice, the infills are commonly treated as non-structural elements, despite their recognised contribution to the structural response of the buildings. The safety assessment of this type of buildings is important and any detailed information is essential, since such information is needed for estimation of the losses that future earthquakes are likely to induce. The present study focuses on the observation and analysis of architectural and structural design drawings of 80 buildings that represent common RC buildings with masonry infill walls located in Portugal. The data were analysed with the purpose of estimating geometric properties of the masonry infill panels confined by RC frames. Fourteen-hundred masonry infill walls were observed and were divided in to different types according to the different dispositions of the openings. Several measurements were performed in order to have deeper knowledge about the percentage of openings that exist in masonry infill walls and consequently in the building’s façade. Infill panels’ dimensions were also determined and other parameters related to the general characteristics of the buildings and the structural elements were also analysed. Parameters such as beams’ and columns’ dimensions and reinforcement details or slab thickness were also analysed. The collected data are utilized to derive probabilistic distributions, whose goodness-of-fit are partially verified with a statistical test. The results from this study can be used in structural modelling development of nonlinear models for masonry infill panels or computation of fragility models. In addition, the statistical parameters such as mean values, standard deviations, probability density functions and their goodness-of-fit have also been investigated for all the entire parameters.

Recent earthquakes show that masonry infill walls should be taken into account during the design and assessment process of structures, since this type of non-structural elements increase the in-plane stiffness of the structure and consequently the natural period. An overview of the past researches conducted on the modelling of masonry infilled frame issues has been done, with discussion of past analytical investigations and different modelling approaches that many authors have proposed, including micro- and macro-modelling strategies. After this, the present work presents an improved numerical model, based on the Rodrigues et al. (J Earthq Eng 14:390–416, 2010) approach, for simulating the masonry infill walls behaviour in the computer program OpenSees. The main results of the in-plane calibration analyses obtained with one experimental test are presented and discussed. For last, two reinforced concrete regular buildings were studied and subjected to several ground motions, with and without infills’ walls.

Abstract: Research on seismic safety assessment has been the centre of great interest among the scientific community in recent years. Although the devastating impact of earthquakes on current society should be incentive enough to increase research, the development of more realistic mechanical behaviour models and the continuous enhancement of computation capabilities are paramount factors contributing a great deal to the increase of such interest. In this context, three research areas can be identified as currently leading to important developments: code related research, especially in Europe where new design codes are in the implementation process; risk analysis, namely concerning the definition of methodologies for safety assessment that involve the evaluation of the failure probability and could be included in future generations of codes; and experimental characterization of constitutive laws which provides support for the development and calibration of accurate and realistic numerical models for seismic analysis and for the adequate characterization of limit state capacities. The paper will present some of the current scientific research trends on these three seismic safety assessment related topics. Studies addressing the seismic safety assessment of structures, either probabilistically or based on code provisions, and that consider realistic nonlinear mechanical behaviour models will be focussed. Reference will also be made to experimental research on the seismic behaviour of structural elements, emphasizing its crucial role to support the development of numerical models simulating the effects of different seismic strengthening techniques. Finally, given the development of studies leading to new trends and perspectives for performance based earthquake engineering, a possible scenario for seismic design in the future is presented, emphasizing the key issues for its implementation.

Abstract: Shear effects are often a very important issue on the seismic behaviour of piers, particularly for hollow section bridge piers. In fact, for this type of piers the cyclic response is similar to that of a structural wall in which both the transverse reinforcement ratio and the detailing can play an important role on its performance, even likely to be determinant in terms of the failure mechanism. On the other hand, codes and design guidelines are usually very conservative concerning shear capacity in order to avoid any shear failure mechanism likely to trigger well known catastrophic consequences. Therefore, research studies on this topic are still needed for a better understanding of pier cyclic shear response and also for improvement of the performance under seismic actions. Pursuing this general objective, this paper partially reports on an experimental/numerical campaign carried out on 1:4 reduced scale bridge piers in order to highlight and investigate shear-type problems. Within the scope of this paper, two specimens types were selected having equal rectangular hollow section (900 × 450 mm2, 75 mm thick) but different transverse reinforcement detailing, namely one with a single stirrup per wall (representative of typical bridge construction without seismic design requirements) and another with multiple stirrups, according to Eurocode 8 provisions. Numerical simulations of the experimental results were also conducted aiming at contributing for complete and consistent interpretations of experimental results. Detailed modelling was performed allowing for realistic simulations of the non linear behaviour, particularly suitable when a significant shear component is involved. Therefore, the numerical strategy was based on a detailed 3D FEM discretization using a two-scalar variable damage model for the concrete constitutive law and a suitable cyclic behaviour law for steel bars represented by truss elements. Results have shown that shear deformation and failure modes are well simulated, while providing detailed insight concerning concrete damage pattern and distribution of yielding on the transverse and longitudinal reinforcement.