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A huge fraction of the worldwide built heritage consists of adobe masonry (AM) structures, including cultural heritage sites protected by UNESCO and single countries. In Portugal, the Aveiro district is a region where approximately 40% of the building stock is composed of AM structures with high cultural, social and architectural value. This paper presents a macro-mechanical finite element (FE) model that was developed for future performance assessments of AM structures. Based on available experimental data on Aveiro’s AM, the FE model was validated in two different boundary and loading conditions associated with normal and diagonal compression tests. A satisfactory numerical-experimental agreement was found in terms of load-displacement curves, crack patterns, local stresses and deformations. A sensitivity analysis evidenced that compressive and tensile strengths mostly influence the peak load capacity and post-peak softening behaviour of wallettes, whereas Young’s modulus affects the pre-peak rising branch of load-displacement curves.

Through long-term monitoring, modal parameters identified in-situ can provide important information about the safety state of civil buildings and infrastructures. Unfortunately, structures are subjected to changing environmental conditions that can mask variations in the dynamic properties caused by damage and, therefore, lead to an incorrect condition assessment. The quantification of the influence of environmental conditions on modal parameters is a crucial step to eliminate their interference in a safety evaluation. Under current state-of-the-art considerations, this step is still an open challenge because environmental variables are time-dependent non-uniform quantities that have different influences on structural systems depending on the predominant material. In this paper, the effects of ambient temperature and humidity on the dynamic properties of earthen constructions are investigated using laboratory tests. A dynamic monitoring system was successfully implemented on adobe walls of different thicknesses to examine the influence of seasonal and daily variations of temperature and humidity. Three 1:1 scale adobe masonry walls were built and exposed to ambient conditions for 240 days. Temperature and humidity variations on the exterior, as well as in the inner walls, were continuously recorded together with the dynamic behavior using ambient vibration. The results provide useful insights on the influence of thermohygrometric parameters on the dynamic properties of adobe systems. The seasonal results indicate unclear correlations of ambient parameters and environmental variables. On the other hand, at a daily scale, the results indicate the existence of a clear relationship between inner measurements and dynamic properties. Moreover, the results indicate the existence of a delayed effect of external ambient parameters in the dynamic behavior of earthen systems., This research was performed by the Engineering & Heritage research group at PUCP with collaboration from the Department of Structural Engineering of the University of Minho in Portugal, and the Department of Civil Engineering at the University of Chile. The authors would like to acknowledge the Directorate of Research Management at PUCP (project No 349-2016) for funding this research. Complementary funding was also received from the program Cienciactiva from CONCYTEC in the framework of the Contract No 222-2015. The first author gratefully acknowledges ELARCH program for the scholarship in support of his PhD studies (Project Reference number: 552129-EM-1-2014-1-IT-ERA MUNDUS-EMA21). The authors acknowledge the contribution of the MEng Rick Delgadillo to the indispensable laboratory work presented in this paper.

We conduct a comprehensive experimental and numerical study of the impact response of lightweight adobe masonry with a density of 1.2 g/cm3. Based on two independent test cases, a simulation model for lightweight adobe is validated and applied. First, we investigate the impact of a spherical projectile on finite and semi-infinite targets. Then, the penetration behavior of a generic hollow projectile is studied. In each case, the data from the ballistic experiments is compared to the results of corresponding numerical simulations. The employed numerical model utilizes a p-a-equation of state, recently derived from planar plate impact experiments on the same lightweight adobe material [Sauer et al., Journal of Dynamic Behavior of Materials 4 (2018) 231-243]. Strength and failure modeling are based on a validated numerical description of another adobe material that has a density of 1.8 g/cm3. The simulation model for lightweight adobe is capable of simultaneously reproducing all experimental results in a quantitatively appropriate way. This reveals that, although the phenomenology and quantitative properties differ significantly, lightweight adobe (1.2 g/cm3) and adobe (1.8 g/cm3) can be described by the same approach. Hence, this work suggests that the utilized model is applicable for analyses of impact loading of the entire class of adobe materials.

Many people live in adobe masonry (AM) constructions in earthquake areas even if most of the existing constructions are not engineered, thus prone to seismic damage. Therefore, seismic retrofitting of existing AM structures is a critical issue. In this study, experimental results of diagonal compression tests on 21 adobe masonry wallets, before and after the installation of textile reinforced mortar (TRM) with either hemp or glass fibres, are presented. Hemp-TRM is found to be more effective than glass-TRM in improving the shear capacity of AM, showing a mean increase in shear strength and ductility of 25% and 260% in hemp-TRM-strengthened wallets and 12% and 100% in glass-TRM-strengthened wallets. The hemp textile allowed compatibility of the TRM to the masonry substrate, preventing premature debonding and local failure. Experimental results are compared to existing data on TRM systems made of vegetable fibres, evidencing a significant capacity enhancement through flax- and hemp-TRM systems.

We investigate the penetration of tungsten-heavy-alloy projectiles into adobe targets. The analysis rests on two complementary parts. Firstly, experimental data comprising impact experiments with five different projectile variants against finite-thickness adobe targets is available. Although the data stems from earlier work, it is presented in full detail here for the first time. The general phenomenology is discussed mainly with respect to projectile failure and stability of the penetration in adobe. Secondly, a recently published hydrocode model for adobe under impact loading is applied without further modification for complementing the experimental results with additional time-resolved insight into the penetration mechanics. For the regime without projectile failure or significant plastic deformation, this hydrocode model is capable of reproducing the experimentally observed projectile-target interaction with good overall agreement between experiments and simulation. While the test data covers different penetration regimes from rigid-body motion to projectile failure, the numerical analysis is restricted to linear-elastic behavior of the impactors, in order to avoid any ambiguity due to the less established projectile material description. With the information from the hydrocode simulations, we are able to reveal the origin of the projectile-specific magnitude of instability in the penetration in adobe. The thereby achieved understanding of the motion of the differently shaped impactors within the formed cavity allows us to discuss possible explanations for the particular projectile failure observed in the experimental data.

Masonry construction is one of the oldest building systems and practiced since the early stage of human civilization. Even though industrialized nations developed new building practices using steel and concrete materials, most developing countries still use unreinforced masonry buildings. Evidence from past events shows that masonry structures sometimes performed well and survived several earthquake events, particularly in the area where earthquake events struck regularly and enough to show how structures behave. However, an alteration from the traditional cultural building practice is seen due to the lack of proper scientific knowledge about such local construction cultures. Amongst traditional construction technics, one captured authorities' and scientists' attention as showing excellent properties: seismic bands that can be found in many parts of Nepal. After the 2015 Gorkha earthquake, reconstruction works started adopting the guidelines developed by DUDBC and National Building code that suggest using such seismic bands. The evidence of using such band dates to 2500 BCE, and qualitative studies of those applications have proven to enhance the performance in the masonry structure. However, the experiment's quantitative parameters using various materials are needed to carry out the parametrical analysis to optimize seismic band's use. To provide quantitative results, we have started with two specimens, one without a band and one with a timber seismic band, and incorporate the digital image correlation (DIC) technique to obtain the localized information. The quasi-static cyclic test is carried out for our specimens to compare the behavior concerning the energy dissipation, and the surface area of the crack formed during the loading cyclic. This work clearly shows the seismic band's advantage in limiting the crack propagation and improving masonry structure integrity.

In Portugal, rammed earth monolithic walls and adobe masonry were, for several centuries, important construction techniques for dwellings. The frequent unnecessary demolition of these buildings, mainly due to lack of information related to them, lack or inadequate maintenance interventions, and advanced state of degradation, has been leading to great cultural and material loss. To preserve this vernacular built heritage and all the technological knowledge related to it, it is fundamental to understand the constructive technologies. Several earthen buildings from Leiria region were mapped and inspected, and two of them were taken as case studies. This architectural survey allowed studying their construction specificities, main building pathology, and thus contributing to Leiria's vernacular earthen buildings efficient preservation and use.

Earth construction is one of the oldest and most widespread construction system. Around 30% of world population lives in earth buildings. About 50% of population in developing countries, including the majority of rural areas, and at least 20% of urban and marginal urban areas, lives in earth buildings. The main general objectives of this study are the behaviour characterisation of adobe and rammed earth constructions along with the research for the development of retrofitting and seismic performance enhancement solutions, considering the relevant earthen heritage built in Portugal. In fact, until the first half of the last century, earth was commonly adopted as a construction material in Portugal. Adobe was used in almost all types of construction in littoral centre, particularly in Aveiro region. The consolidation of the knowledge on this technique and on the mechanical behaviour of adobe masonry will play a fundamental role on the preservation of the earthen built heritage. In addition, it may contribute to the development of innovative earth construction solutions for new buildings, following current concerns but also respecting structural safety demands, which will allow accommodating the increasing interest on this type of building solutions. The mechanical properties of adobe units and mortars were studied and a series of tests for the characterization of the adobe masonry behaviour were carried out, in the Department of Civil Engineering of the University of Aveiro, namely: (i) bond strength and (ii) joint shear tests. Additionally, a full-scale adobe building model was subjected to monotonic and cyclic horizontal lateral loads until failure. The present paper present the main results and conclusions of the experimental campaign developed.

The micromechanical behaviour of running bond adobe masonry with straw fibre reinforced bricks is investigated. Finite element analysis was carried out under the assumptions of periodic masonry, plane stress conditions, and unit cell subjected to principal stresses only, leading to derive critical curves. Both classical elasticity and bi-modular theories were applied to bricks and mortar, adopting appropriate measures for shear modulus. Analysis results are compared in terms of critical curves, highlighting the effects of the elastic model (i.e., constituent materials with equal or different Young's moduli in tension and compression), strength and modulus ratios between mortar and bricks, and mortar joint thickness.