Seismic design of tension wall-diaphragm anchorage for historical unreinforced masonry buildings

The absence of appropriate structural connections is known to be one of the main factors contributing to the activation of out-of-plane mechanisms of masonry walls that can compromise the entire stability of a building. The high vulnerability of historical unreinforced masonry buildings to these types of mechanisms imposes the necessity to develop engineered strengthening solutions capable of ensuring positivewall-diaphragm anchorage to work in tension.A design methodology was developed covering aspects related to the estimation of the seismic demand and the design of a retrofit solution studied experimentally. The procedure proposed relies on the assessment of the resistant capacity associated with several possible failure modes and the estimation of the seismic demand considering the existing recommendations found on Eurocode 8 (CEN/TC 250 2010), ASCE/SEI 41-13, and NZSEE (2006).The authors would like to acknowledge Professor Jason Ingham for providing essential information and technical expertise concerning the NZSEE (2006) application. This work was partially funded by project FP7-ENV-2009-1-244123-NIKER of the 7th Framework Program of the European Commission, and by FCT, within ISISE, project UID/ECI/04029/2013, which are gratefully acknowledged

Caracterização experimental do reforço de ligações parede-piso

O desempenho sísmico de edifícios tradicionais de alvenaria é geralmente afetado pela eficiência das ligações piso-parede, uma vez que estas podem assegurar a continuidade estrutural e impedir a maioria dos colapsos locais. De facto, o comportamento para fora do plano das paredes de alvenaria observado em sismos recentes evidencia a importância crítica que as ligações entre os elementos verticais e horizontais assumem em edifícios históricos. A literatura científica neste domínio é muito escassa, justificando a necessidade de investir recursos na análise, experimental e numérica, do comportamento das ligações piso-parede. Este artigo apresenta uma série de ensaios experimentais sobre a caracterização do comportamento de ligações piso-parede em construções tradicionais de alvenaria. Foram construídos diversos provetes em laboratório à escala real, representativos dos edifícios pombalinos tardios e gaioleiros da baixa de Lisboa. O artigo discute os resultados experimentais das ligações reforçadas ensaiadas, com destaque para as cargas e deslocamentos máximos, bem como os modos de rotura associados. Com base nos resultados obtidos, é apresentada ainda uma idealização bilinear das envolventes dos ensaios, como primeira aproximação à utilização prática dos resultados

Local seismic cultures: the use of timber frame structures in the south of Portugal

Given the fact that using timber frame structures has proven to improve the seismic behavior of vernacular architecture, as has been reported in past earthquakes in many countries, its preservation as a traditional earthquake resistant practice is important. This paper firstly intends to evaluate whether the use of timber frames as a traditional seismic resistant technique for vernacular architecture in the South of Portugal, traditionally a seismic region, is still active. Secondly, the city of Vila Real de Santo António was selected as a case study because it also followed a Pombaline development contemporary to the reconstruction of Lisbon. The plan included the provision of timber frame partition walls for some of the buildings and, thus, an overview of the type of constructions originally conceived is provided. Finally, the alterations done in the original constructions and the current state of the city center are described and the effect of these changes on the seismic vulnerability of the city is discussed.The authors wish to express their gratitude to the Portuguese Science and Technology Foundation (FCT) for the scholarship granted in the scope of the research project 'SEISMIC-V-Vernacular Seismic Culture in Portugal' (PTDC/ATP-AQI/3934/2012)

Connections and dissipative systems with early warning

The global response of historic buildings is determined by the behaviour of the single structural elements as well as by their mutual connections. Consequently, in the last decades a number of technical solutions for the improvement of structural connections have been developed in response to the increasing demand in the field of the seismic protection of heritage assets. At the same time, the experimental assessment of structural strengthening techniques is a well established practice both in the scientific community and among commercial producers. It is therefore surprising how testing of connections is rarely performed and very few codes of practice deal with it. Additionally, the few existing experimental procedures for testing connections are neither standardised nor easily accessible to end users. Within the framework of the EU-funded NIKER project, Work Package 6 aims to address such technical gap through the development of procedures specific to the strengthening of structural connections of historic buildings