Browsing by Author "Todisco , Leonardo"

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Database with compression and bending tests on unbaked earth specimens and comparisons with international code provisions
(2021) Todisco , Leonardo
In an effort to calibrate assessment methods of existing earth structures, a new database with compression and bending tests on unbaked earth specimens was assembled. The data-collection database includes 2670 tests with specimens of four different materials: non-stabilized and stabilized adobe, compressed earth block (CEB) and stabilized compressed earth block (SCEB). This paper ﬁrst presents the data included in this data-collection database. Subsequently, for the purpose of comparing these results with international code provisions, several control and ﬁltering criteria were applied. As a result of this process, 2631 tests remained in the evaluation database. In light of this analysis, the compressive strength obtained from the experimental tests was compared with values proposed by the international codes. As main result, experimental tests generally show a compressive strength lower than the minimum required by international codes, which are the Peruvian and the Spanish code, respectively, for adobe and CEB.
Geometry and proportions of adobe vernacular buildings in Cuenca, Ecuador
(2021) Vergara Peñaherrera, Eliana Marcela
The Historic Centre of Cuenca, recognized as World Heritage Site since 1999, is characterized by the relevant presence of traditional buildings which load-bearing structural elements are made of unbaked earth. Despite representing a unique example of vernacular architecture, an in-depth analysis of the buildings’ geometric features as their vulnerability against seismic actions is still missing. First, this paper presents a brief description of the most common construction system of these constructions. Next, 45 case studies are investigated with the support of in-site surveys carried out by the authors. In light of these investigations, this research sheds light on the geometrical configuration of these constructions and offers a new interpretation of their architecture. Finally, the geometrical data gathered in the surveys are compared with the recommendations given by international codes and analysed providing a first preliminary assessment of their structural vulnerability and insights on the most vulnerable case studies.
Influence of additives on the structural performance of cement-stabilised rammed earth
(2021) Samaniego Galindo, Cristina Estefania
The influence of additives on the structural behaviour of cement-stabilised rammed earth was investigated through an experimental programme based on 13 different mixes with varying cement contents (6, 8 and 10% by earth weight) and three different types of additives (superplasticiser, air-entraining agent (AEA) and hardening accelerator). In total, 156 specimens were fabricated and tested at 7 and 28 days in order to compare their compressive strength and other properties such as stress–strain relationships, shrinkage and workability. The results highlighted the essential role of cement in increasing the compressive strength of the material. Specifically, cement contents of 6%, 8% and 10% corresponded, respectively, to strength increases of 41%, 80% and 92% compared with the reference mix with a mean compressive strength of 1.15 MPa. The AEA was found to be the most effective additive for increasing the compressive strength, with obtained strengths of up to 2.93 MPa (an increase of 155% compared with the reference mix). The efficiency of each mix was evaluated through a strength/cost ratio. In addition, an overall comparison of compressive strength, shrinkage, deformation, cost and workability was performed using an analytic hierarchy process. Finally, the experimental results were compared with the mechanical requirements of various codes.
Loss estimation for typical adobe façades of Cuenca (Ecuador) due to earthquake scenarios
(2021) Cárdenas Haro, Xavier Ricardo; Tarque Ruíz, Sabino Nicola; Todisco , Leonardo; León González, Francisco Javier
A relevant percentage of the world population lives in constructions made of sun-dried earth, which are built according to several techniques such as rammed earth, bahareque or adobe. This work specifically focuses on the adobe buildings located in the Historic Centre of Cuenca (Ecuador), recognized as a World Heritage Site since 1999. Although these buildings are characterized by different geometrical and material configurations, all of them have load-bearing façade walls made of adobe. This paper illustrates an analysis of the seismic vulnerability of these adobe façade walls according to different geometrical configurations and considering an out-of-plane loading. This study is based on original in-situ collected data about 45 one and multi-storey buildings. The seismic behaviour of the case studies is investigated through a demand versus capacity analysis based on 5 different failure mechanisms and considering a variable intensity of the seismic action. This procedure has allowed to classify the case studies according to their seismic vulnerability and to identify the most relevant failure mechanisms in such adobe façades. As a main result, some continued fragility curves have been produced to allow replicating this procedure to buildings with similar features. Finally, a repair cost estimation after seismic scenarios is estimated.