Rogiros Illampas

Overview of the Pathology, Repair and Strengthening of Adobe Structures

Adobe construction is considered to be an important feature of the international architectural heritage. To achieve the effective preservation of culturally significant adobe structures, the factors that cause their deterioration should be recorded and understood and the result of potential restoration interventions should be evaluated. This study reviews the pathology of adobe structures and the various restoration methods currently in use. Focus is given on the main agents of adobe deterioration and commonly encountered decay mechanisms. The applicability and efficiency of several repair and strengthening techniques currently used in practice or proposed by academic researchers is critically discussed and the gaps that occur in the field of earthen masonry retrofitting are highlighted. An extensive list of references, which reflects the international knowledge and experience on the topic, is also provided.

A study of the mechanical behaviour of adobe masonry

Adobe buildings are encountered in almost every region of the world and constitute a significant feature of the international cultural heritage. However, the behaviour of adobe materials and earth masonry has not yet been adequately investigated. This study aims to examine the mechanical properties of mud bricks from Cyprus and the structural response of adobe masonry. Experimental results obtained from the compressive and flexural strength testing of local adobes are presented and analyzed. In addition, the outcomes derived from the implementation of compression tests on adobe assemblages are discussed. Furthermore, the response of earth masonry to cycles of compressive loadingunloading is examined through numerical simulation. Finally, critical issues to be addressed by future research are identified.

Experimental Investigation of the Structural Response of Adobe Buildings to Lateral Loading Before and After the Implementation of Compatible Grout Repairs

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 experimental 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 sections 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.

Non-linear Dynamic Finite Element Analysis of Adobe Masonry Structures with Various Roof Diaphragm Configurations

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.

ASSESSMENT OF STONE MASONRY WALLS WITH DETERIORATION AT THEIR BASE USING NON-LINEAR FINITE ELEMENT ANALYSES

Masonry walls are exposed to various potentially damaging factors, which arise due to common environmental effects or accidental actions. Local damage on a masonry wall operating as a primary load carrying component may trigger partial or full collapse of the wall and of the structural system it is supporting. Therefore, reliably assessing (potentially) damaged masonry walls is a crucial aspect in maintaining the desired safety level and decide the appropriate retrofit measures possibly required. In the present work, the influence of deterioration at the base of stone masonry walls on their structural response is investigated. For this purpose, plane stress non-linear Finite Element (FE) analyses are performed for various wall configurations and base deterioration scenarios. Hence, the in-plane lateral strength is computed for walls, which are artificially damaged by notionally removing masonry material from the walls’ base. By comparing the remaining carrying capacity of a ‘damaged’ wall with the carrying capacity of the corresponding intact wall, the structural damage tolerance of the deteriorated wall can be quantitatively assessed. The results obtained demonstrate the effects of base deterioration on the lateral resistance of stone masonry walls and facilitate the decision making process for a possible smallor largescale intervention.

Adobe: An Environmentally Friendly Construction Material

This paper describes how adobe is one of the oldest and most widespread forms of construction. Although technologically simple, this material has the potential to produce durable buildings of considerable architectural sophistication that are appropriate for arid climatic conditions and have a wide range of uses. This is true in both vernacular and ‘modern’ contexts. Moreover, adobe is an environmentally friendly material that does not require additional energy resources for its production and application, it can be fully recycled and it creates minimal levels of waste when disposed. Since most building techniques related to earth-based materials have been systematically neglected during recent decades, there is an imminent need to “rediscover” adobe through academic research. This paper reports on the first findings of a research program that was aimed at examining adobe structures in Cyprus. The authors present a review of the use of adobe on the island and the main causes of deterioration of adobe structures. The authors also mention techniques currently used for the restoration of traditional adobe buildings and they report some preliminary laboratory results of tests carried out on local adobes.