Case Study of the Old City Centre of Seixal, Portugal, Rebuilt After the Great 1755 Lisbon Earthquake
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ENGINEERING STRUCTURES AND TECHNOLOGIES ISSN 2029-882X / eISSN 2029-8838 2015 7(3): 126–139 doi:10.3846/2029882X.2016.1123903 STRUCTURAL AND ARCHITECTURAL CHARACTERISATION OF OLD BUILDINGS STOCKS: CASE STUDY OF THE OLD CITY CENTRE OF SEIXAL, PORTUGAL, REBUILT AFTER THE GREAT 1755 LISBON EARTHQUAKE Tiago Miguel FERREIRAa, Cátia SANTOSb, Romeu VICENTEa, J. A. R. MENDES DA SILVAb aRISCO, Department of Civil Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 Aveiro, Portugal bLAETA, Department of Civil Engineering, University of Coimbra, Rua Luís Reis Santos, Pólo II da Universidade, 3030-788 Coimbra, Portugal Received 28 May 2015; accepted 02 November 2015 Abstract. This paper addresses the issue of historical urban centres from the perspective of the analysis and inventory of building features. The cataloguing process of the building typologies is presented herein as a synthesis of the main construction forms, using as a case study the old city centre of Seixal, Portugal, rebuilt in its present form after the great 1755 Lisbon earthquake. As marks of an historical and architectural heri- tage, old urban centres should be protected, safeguarded and potentialised. Therefore, it is essential to have a complete understanding of the diachronic process of both buildings and urban mesh, in order to support qualified, conscientious and sustainable interventions. Keywords: historical building centres, built heritage, building typologies, constructive characterization, re- habilitation. Introduction survey campaign wherein 99 out of 380 old mason- ry buildings, focusing on three different domains: Throughout time, cities are exposed to numerous (i) architectural typologies and drawings; (ii) structur- events, with different origins and impacts, which go al and non-structural building features and defects and changing their image and characteristics. In conse- (iii) socio-demographic characterisation, which will be quence of the 1755 Lisbon earthquake, several cities individually discussed throughout this paper (further were affected, and a large amount of built heritage was results in these domains can be seen in Ferreira et al. irretrievably lost. The city of Seixal, located about 25 (2013) and Santos et al. (2013)). km south of Lisbon, was one of the most affected ones, going through a long and deep reconstruction process, 1. Inspection and buildings appraisal which represented a main role in the current image of the city. 1.1. Practice of survey, appraisal and inspection Thus, this paper aims at presenting an up-to-date Survey is the starting point for guidance and recom- overview of the built heritage in the old city centre of mendations in the repair and refurbishment of build- Seixal, particularly concerning materials and process- ings. The approach defined for the appraisal must be es used in their reconstruction after the 1755 Lisbon adapted to the aim and typology to be inspected and earthquake. The research work is based on a detailed should necessarily reflect the final intent pursued, the Corresponding author: T. M. Ferreira E-mail: [email protected] Copyright © 2015 Vilnius Gediminas Technical University (VGTU) Press http://www.tandfonline.com/TESN 126 Engineering Structures and Technologies, 2015, 7(3): 126–139 127 depth and the detail of the inspection, the scale of in- lowed three essential phases: survey framework prepa- tervention and the recording tools that are expected ration, fieldwork and data processing. During inspec- to be used. tion and diagnosis campaigns, several difficulties and In the particular case of old buildings, the lack of limitations are commonly felt, namely: reluctance of knowledge on the traditional techniques and materi- some tenants and home owners to allow the inspec- als often leads to inadequate survey techniques which tion; absence of design projects which would help to impair a correct diagnosis and, consequently, the ef- understand structural behaviour and to identify crack- ficiency of subsequent retrofitting or strengthening ing phenomena; physical and financial constraints to interventions. In this context, ISO 13822 (ISO 13822: carry out more precise/conclusive inspections using 2003) and the International Council on Monuments destructive and non-destructive testing for the diag- and Sites (ICOMOS) (ICOMOS/ISCARSAH Commit- nosis; unknown history of undated building changes tee 2005) establish guidelines and recommendations (Vicente et al. 2015). on the assessment and preservation of built heritage. Regarding inspection, the need of a thorough un- 1.2. Development of inspection survey checklists derstanding and knowledge on the structural typology, As part of this work, five survey checklists were devel- building materials and immaterial characteristics is oped, improved and used to survey each construction evident. ISO 13822 and ICOMOS also stress the im- element (roofs, façade walls, timber floors, internal portance of collecting accurate historical information partition walls etc.). Table 1 presents the hierarchical concerning the building construction chronology, even organisation of the inspection and diagnosis checklists. before any appraisal of building defects and damage The initial intent was to create checklists not only evaluation. to record defects and problems, but also to register Among others, a rational approach of the survey construction features and typology. It is worth not- stage must be guided by the following principles: ing that the checklists should always be complement- – Each traditional building is unique, present- ed with photographic documentation and drawings ing different and singular aspects which lead to schemes in two levels of detail: a first level correspond- slightly different survey needs; ing to an expedite handmade drawing of the building; – The selection of the means of inspection, ap- and a second level corresponding to an accurate repre- praisal and recording must be adapted to the sentation of the building in a CAD system to support nature of the building, physical and in-situ limi- rehabilitation actions. tation of survey actions and available resources; The data resulting from the inspection work was – The approach to define a survey strategy is subsequently processed in a database management clearer when at stake is a decision-making pro- system integrated into a GIS application developed to cess and what is to be learned. Therefore, ques- manage, compare and analyse the information. It is tions such as: construction method, modifica- worth mentioning that this work represented a singu- tions over time, nature of materials, mutable use lar opportunity, allowing the appraisal, diagnosis and of the buildings, heritage acknowledge impor- inspection of building stock dating from the 18th to tance and long-term conservation actions are the 20th centuries. the major guidelines; – The survey is a multidisciplinary task. Thus, 2. Urban and architectonical characterisation the contribution of different professionals (en- 2.1. Notes about the urban expansion of Seixal gineers, architects, conservators, historians, archaeologists etc.) with expertise opinion is Originating from a small settlement of fishermen, valuable; Seixal developed due to the proximity to Lisbon, the – The use of several sources of information, such capital of Portugal and of the Portuguese Discoveries. as the documentary information, is also very Seixal’s occupation was connected to its location near valuable and should be considered. the river and its natural resources (see Fig. 1). Build- Lastly, the surveying task usually combines in- ings before the earthquake of 1755 would have rep- spection, diagnosis, testing and recording. In this resented a more medieval conception, matching the sense, the methodology used in this case study fol- general idea of some studies on old urban buildings: 128 T. M. Ferreira et al. Structural and architectural characterisation of old buildings stocks: case study... Table 1. Hierarchical organisation of the checklists Checklists Check-list A A General information of the building General identification B1 Evaluation of roofs and coverings of the building B2 Evaluation of external façade walls Check-listsB B3 Evaluation of floor slabs and coverings Check-listsE Durability Installation of materials B4 Evaluation of interior partition walls, efficiency (non-structural ceilings, window frames Evaluation of the level C Evaluation of structural quality and safety of conservation of buildings D1 Evaluation of ventilation, salubrity and natural lighting and living conditions D2 Evaluation of thermal and acoustic conditions E1 Evaluation of the efficiency water systems Check-list C and sewerage networks Check-listsD Structural Environment quality E2 Evaluation of the electrical network and telephone wires and comfort and safety E3 Evaluation of fire risk and security of the urban mesh. The second phase is related to the expansion along the Tagus River, towards east. It is also worth mentioning that the further the houses were from the river, the poorer and smaller they were, be- ing occupied by low social status inhabitants. Later, in the 19th and 20th centuries, better quality constructions were built along the larger street mesh, attesting to the social conditions of their owners. The riverside street was dedicated to the river businesses, and so were its buildings, directly connecting the warehouses, work- shops and taverns to the river. This way, all the fluvial Fig. 1. Aerial view of the old city centre of Seixal activity