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This paper discusses the challenges in using natural fibers for the development of textile-reinforced mortar (TRM) composites with pseudo-strain-hardening and multiple cracking behavior. The particular characteristics of natural vegetal fibers are analyzed with reference to data from the literature. It is concluded that the efficient use of these fibers as composite reinforcement requires the development of treatment or impregnation protocols for overcoming durability issues, eliminating crimping effects in tensile response and imparting dimensional stability. Relevant experimental research on the synthesis and performance of natural TRMs is reviewed, showing that the fabrication of such systems is, at present, largely based on empirical rather than engineering design. In order to set a framework regarding the properties that the constituents of natural TRM must meet, a comparative analysis is performed against inorganic matrix composites comprising synthetic, mineral and metallic reinforcement. This highlights the need for selecting matrix materials compatible with natural fibers in terms of stiffness and strength. Furthermore, a rational methodology for the theoretical design of natural TRM composites is proposed. First-order analysis tools based on rule-of-mixtures and fracture mechanics concepts are considered. Based on the findings of this study, paths for future research are discussed.

The present study investigates the optimization of the sustainability characteristics of an innovative masonry wall system. The proposed construction technology is based on the use of modular load-bearing masonry units that can accommodate thermal insulation materials either embedded within their core or attached as external leaves on their face. The present study investigates alternative geometric configurations of the masonry system, in order to further improve its overall performance. The investigation aims to find the optimal geometry in terms of thermal performance, structural integrity and ergonomics. Following the selection of the optimum solution, alternative scenarios for the use of insulation were investigated in order to further improve the thermal performance of the selected geometry. Based on the findings, a significant improvement of the thermal performance and ergonomics can be obtained from the creation of rows of voids, without significantly compromising the compressive strength of the units. Also, further improvement of the overall thermal performance can be obtained with the proper use of insulation, without posing a significant burden on the environmental impact of the end-product.

The concepts of structural assessment and retrofit of historical constructions are of particular complexity and require advanced knowledge in material science, conservation techniques and structural analysis. In particular, adobe constructions, given their low mechanical properties and brittle failure modes, are in immense need of comprehensive assessment and retrofitting plans. The current work focuses on the adobe Church of Kuñotambo in Peru, having experienced long periods of deterioration and earthquake-related damage. Under the ongoing Seismic Retrofitting Project (SRP) of the Getty Conservation Institute (GCI), the structural assessment of the church initiated in 2015 confirmed the low lateral capacity of the building and the poor connectivity between the structural parts. Based on the existing cracks and damage, a strengthening scheme was optimized and validated. After the implementation of the retrofitting plan, the quality of its execution and efficiency were assessed in 2019 with a new in situ campaign, which included ambient vibration testing (AVT) and sonic testing. From the acquired field data, the FE model of the retrofitted church was optimized, by updating the stiffness properties of masonry and discontinuities. Moreover, nonlinear static analyses were performed on the updated model in all in-plan directions. Finally, a displacement-based performance assessment was undertaken, under different earthquake limit states, demonstrating the adequacy of the retrofitting., Partial funding by Getty Conservation Institute – Seismic Retrofitting Project.

Fabric reinforced cementitious matrix (FRCM) composites, also known as textile reinforced mortars (TRM), an inorganic matrix constituting fibre fabrics and cement-based mortar, are becoming a widely used composite material in Europe for upgrading the seismic resistance of existing reinforced concrete (RC) frame buildings. One way of providing seismic resistance upgrading is through the application of the proposed FRCM system on existing masonry infill walls to increase their stiffness and integrity. To examine the effectiveness of this application, the bond characteristics achieved between (a) the matrix and the masonry substrate and (b) the fabric and the matrix need to be determined. A series of experiments including 23 material performance tests, 15 direct tensile tests of dry fabric and composites, and 30 shear bond tests between the matrix and brick masonry, were carried out to investigate the fabric-to-matrix and matrix-to-substrate bond behaviour. In addition, different arrangements of extruded polystyrene (XPS) plates were applied to the FRCM to test the shear bond capacity of this insulation system when used on a large-scale wall.

Numerical assessment of adobe structures allow several drawbacks of experimental testing to be overcome, either to carry out back-analyses or to predict the seismic performance of real constructions. Among a number of modelling strategies, this chapter presents the main features of the finite element method, discrete element method and equivalent frame method, discussing their implementation in the case of adobe constructions. Pros and cons of each modelling approach are identified in view of real-world applications. Recent developments are discussed and research needs are detected for future studies.

Recent challenges faced by humanity in relation to the ongoing climatic changes around the globe, have led many practitioners and researchers search for new environmentally friendly materials to use in construction, such as earth-based materials. A specific form of an earth-based building material that nowadays receives particular attention is Compressed Earth Blocks (CEBs). CEBs comprise of soil mixed at low moisture content and are formed under high pressure in compression, without firing. The end-products can be non-stabilized, i.e., without any cement or lime added, or stabilized, whereby a small quantity of stabilizer (In Cyprus, CEBs were not used in the past, as the prevailing earth building technique on the island was adobe masonry. Recently, however, there appears to be an interest in the use of this material for contemporary construction. The work hereby presented is part of an ongoing research project that focuses on the design, production and characterization of a sustainable and eco-friendly prototype CEB masonry system that will be fabricated using raw materials originating from Cyprus. The project is funded by the European Regional Development Fund and the Republic of Cyprus, through the Cyprus Research and Innovation Foundation (Project ENTERPRISES/0618/0007).In the framework of the aforementioned project, various types of locally sourced soils, with different mineralogical/granular composition and plasticity characteristics have been selected and used for the production of non-stabilized CEBs. A series of tests, including particle-size analysis, Atterberg limits determination, shrinkage and compaction measurements, and X-ray diffraction analyses have been carried out to determine the characteristics of the raw materials selected. In addition, compression and 3-point bending tests, capillary absorption measurements and thermal conductivity analyses have been conducted to assess the physico-mechanical properties of the CEBs produced.XRD analyses have shown that the soils investigated are mainly composed of carbonates and silicates at different ratios. Preliminary capillary absorption tests have demonstrated that the use of a non-reactive liquid, such as acetone, is better over water in determining the sorptivity of non-stabilized CEBs. In addition, the thermal conductivity of all specimens ranged between 0.60-0.85 W/mK. Finally, the results suggest that, despite the different granular composition of the soils used, all soils demonstrated adequate mechanical properties in terms of compressive (over 5 MPa) and flexural (over 0.5 MPa) strength.

This paper examines two different procedures for the seismic appraisal of the ruinous medieval St. Mary of Carmel stone masonry church in Famagusta, Cyprus. A detailed survey that included field tests for the identification of the modal characteristics of the structure together with laboratory and in situ tests for assessing the composition and properties of the monumental materials was performed. The results were used for the formulation and calibration of a finite element model representing the monument. The seismic behavior of the latter was examined via nonlinear static and time-history analysis. It was found that due to the lack of spatial continuity and the absence of a roof diaphragm, various parts of the monument tend to act as discrete macro-blocks and localized failure mechanisms occur. Comparisons made between the results yielded by the different analysis methods, revealed that the implicit dynamic approach gives more realistic predictions of damage distribution. Nevertheless, the ultimate collapse modes obtained by both methods show relatively good agreement and are in line with field observations. Capacity estimations suggest that the case-study monument fails to satisfy regional seismic demands and underline the high vulnerability exhibited by heritage ruins. It is thus concluded that further research is required in order to develop procedures particularly suited to the seismic appraisal of heritage ruins and to the design of appropriate interventions for collapse prevention., The work undertaken by the University of Cyprus for the characterization of the building materials was partly funded by the United Nations Development Programme – Partnership for the Future (UNDPPFF). The authors (IR and II) would like to acknowledge the support of Platonas Stylianou & Associates – Civil and Structural Engineers L.L.C, who facilitated the site visits and provided the architectural drawings of the monument. They would also like to thank Dr. M. Theodoridou for her help with the in situ and laboratory tests.

This study examines - by means of numerical analysis - the thermal, environmental and structural performance of an innovative modular masonry system that is currently under development. Focus is given on investigating the response of the system when alternative geometries of brick units are used and different insulation materials are incorporated into the core of the masonry. Heat flux analysis is performed to examine temperature distribution within the structure and to estimate its U-value. The embodied energy of the assemblage is computed and compared against commonly used masonry systems.Furthermore, non-linear Finite Element (FE) simulation is conducted to assess load resistance. Results indicate that the proposed solution has the potential to produce energy efficient and structurally sound constructions.

In the framework of this study, a 1:2 scaled replica of a traditional single-storey adobe building was constructed and tested at the laboratories of the University of Cyprus. The main objectives of the exper-imental program were to evaluate the structural performance of adobe buildings under horizontal loads (simulating seismic action) and to investigate the effectiveness of cracking repair by means of injection with a compatible grout. The model was initially subjected to a series of monotonic static lateral loading cycles that led to the development of extensive cracking damage and to significant reduction of the load-bearing capacity and overall stiffness. A compatible clay-based grout was then developed using the same soil as the one composing the model’s adobes. This material was injected into the cracked sec-tions of the masonry and the repaired model was re-tested. The clay-based grout successfully restored structural continuity, precluding the re-opening of injected cracks during subsequent loading cycles. The recorded load-deformation response revealed that the grout repair reinstated the original stiffness of the structure and recovered more than 90% of the initial lateral strength. The results indicate that clay-based grouts can be used for re-establishing the stability of adobe constructions under static loads., POCI-01-0145-FEDER-007633; POCI-01-0145-FEDER-016737; PTDC/ECM-EST/2777/2014

The present study is part of a wider research program, which aims at the development of an innovative modular masonry construction system that integrates environmental passive strategies, as well as high energy efficiency. The paper focuses on the parametric numerical study of the proposed construction component. Within this context, the energy performance achieved by alternative geometries of the masonry unit, as well as the use of different constituent materials and insulation fillings, are examined. Through the parametric analysis of alternative proposals, arising from the combination of the above features, reaching to the optimum solutions, in terms of energy efficiency, was achieved. For the above study, computational models were developed and analysed using Matlab R2014a. Furthermore, the environmental impact, associated with the material used for the fabrication of the masonry construction component, was assessed through the environmental analysis of the embodied energy and CO₂ emissions of the proposed component. It is concluded that the proposed system’s thermal performance relies primarily on the characteristics of the constituent material composing the modular masonry unit, the geometry of the unit and the use of insulation. In terms of environmental impact, both the constituent material used, and the type of insulation material installed, have a considerable effect on the end-product’s total embodied energy.DOI: http://dx.doi.org/10.5755/j01.sace.16.3.16174

Severe and repeated earthquakes devastated Cyprus in antiquity, causing in many cases the abandonment of entire settlement sites. Yet, information regarding the level of seismic activity of historical seismicity in Cyprus is very limited and does not provide the evidence to arrive at reliable conclusions relative to hazard damage parameters such as the severity or occurrence frequency of a seismic event. Thereafter, the level of risk in which these monuments are exposed is unclear leading to an increased uncertainty regarding their safeguarding from future events. The paper aims at investigating the correlation between damage observed in underground ancient tombs and the historical seismic activity at the area based on in situ observations and expert opinion analysis. In addition, the paper aims to simulate the current state of the tomb's structure, and predict, through a seismic scenario, the propagation of damage from future large earthquake events. Underground monuments are chosen since, due to the nature of the seismic force, they are further “protected” and capable of surviving strong ground motions as they follow the displacement of the soil surrounding them. Typical examples of such structures in Cyprus are the hypogea in the necropolis of the “Tombs of the Kings”, located in Paphos area. Some of these monuments exhibit severe cracking of the rock-cut stone walls and evidence of collapse of vertical resisting members of skeleton structure. Paphos area is the most active seismic region in Cyprus based on the historical catalogue of events with evidence of a number of destructive earthquakes. The framework presented herein utilizes information regarding the current geometry of these structures as documented from topographical surveys, their depth, area of opening, size of resisting members along with information regarding the geotechnical conditions at the site to arrive at estimates of the displacement demand under various seismic scenarios. The predicted shear strain levels on the walls are compared with the strain capacity under tension of the soil material to identify the possibility of propagation of cracking of the walls based on a specific seismic scenario.

This paper deals with the assessment of adobe structures using non-linear dynamic Finite Element (FE) analysis. Numerical simulation of adobe masonry follows a continuum approach and is based on brittle fracture concepts that are expressed through a damaged plasticity constitutive law. The selection of appropriate modelling parameters is hereby discussed. Spatial FE models representing a traditional single-storey dwelling, before and after the implementation of certain strengthening interventions which modify the roof diaphragm configuration, are developed. The FE models are subjected to time history analyses using a real time accelerogram from a past earthquake. Comparisons among the structures’ seismic responses are made in terms of the predicted damage distribution, displacement capacity and overall lateral resistance. Useful conclusions regarding the effect that different roof diaphragm configurations may pose on the dynamic behavior of adobe structures are derived. Finally, critical issues that future research should address in order to enable the efficient computational analysis of earthen structures are identified.