Masonry walls retrofitted with natural fibers under tsunami loads

AbstractIn the last decades, several tsunamis hit international coasts and engaged scientific awareness to the retrofit of coastal buildings against tsunami loads. Structural design under tsunami loads is difficult due to the high uncertainties of the phenomenon. Local collapse mechanisms of masonry walls, like as out of plane mechanisms, have an high probability due to flexural actions; a higher flexural capacity can be reached using specific retrofit systems; in particular, this paper aims to deepen the behavior of masonry walls retrofitted with innovative retrofit systems like as natural fibers applied with inorganic mortar matrices. The retrofit of structures under tsunami actions could be an innovative research topic for international research community dealing with coastal buildings located in areas characterized by a high tsunami risk. Recent engineering applications demonstrated the innovative strengthening systems to be effective for the retrofit of existing masonry buildings. These strengthening systems are of great interest in the practical applications due to the low costs and their sustainability. In fact, the lower costs compared to the synthetic fibers allow their diffusion in emerging countries. In a first part the impact of constituents on the structural capacity of masonry elements strengthened with natural systems has been discussed. Important results have been provided in order to improve the knowledge and encourage the development of these systems in many engineering applications. Finally, the effects of retrofit systems on masonry walls under tsunami loads will be discussed in terms of critical inundation depth variations before and after the interventions

Tsunami risk communication and management: Contemporary gaps and challenges

Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures

Vulnerability of coastal italian residential masonry buildings under tsunami loads

The main aim of this thesis is to assess the vulnerability of coastal Italian residential masonry buildings under tsunami loads and it represents a contribution in the tsunami risk assessment. The structural vulnerability of masonry buildings is investigated considering the activation of in-plane and out-of-plane local mechanisms due to flexural and shear failure modes. Several Monte Carlo analyses are performed in order to simulate the behaviour of Italian masonry buildings based on national census database, assuming a regional scale approach. Furthermore, damage scenarios are evaluated in terms of number of damaged buildings, reconstruction costs and potential casualties, based on structural analyses results, in the case of a tsunami event on the Italian coasts. Inundation and thematic maps are realized in a GIS system

Simplified approach to assess the vulnerability of masonry buildings under tsunami loads

In the last years, several catastrophic tsunami events engaged scientific awareness to assess the tsunami risk. Fragility curves are required to analyse the vulnerability of masonry buildings and analytical fragility curves should be based on local buildings typologies. This paper aims to assess the vulnerability of masonry buildings under tsunami loads by means of the minimum inundation depth triggering a failure mechanism coherently with a large scale approach and consequentially, a low knowledge level achieved on properties of structures. Furthermore, out-of-plane and in-plane mechanisms activation is investigated by modelling an external tsunami load pattern with simplified assumptions. Shear and flexural failure are analysed as main in-plane failure modes while horizontal and vertical bending mechanisms are considered as main out-of-plane failure modes. Masonry walls are modelled as frame elements and masonry is modelled as a nonlinear material. Japanese guidelines are assumed to model tsunami loads instead of more refined models, such as ASCE 7-16 and FEMA P-646 proposals, due to reduced achievable knowledge level. Proposed mechanical models provide important information about vulnerability of masonry buildings under tsunami loads and they represent a basic step to provide vulnerability information on masonry buildings at a regional scale level

Out-of-Plane Retrofit of Masonry with Fiber-Reinforced Polymer and Fiber-Reinforced Cementitious Matrix Systems: Normalized Interaction Diagrams and Effects on Mechanisms Activation

Nowadays retrofitting and strengthening of masonry buildings are important challenges for structural engineering to ensure the structural safety under seismic or exceptional loads. This paper aims to clarify the effects of strengthening systems on out-of-plane mechanisms activation, such as horizontal and vertical bending mechanisms, by analyzing P-M interaction diagrams according to available international design guidelines. They enable the assessment of structural behavior of strengthened masonry walls under different external loads. Dimensionless equations of maximum bending moment capacity of masonry cross sections retrofitted with composite strengthening systems are derived, assuming different failure modes such as crushing of masonry and rupture of the strengthening system. Parametric analyses are performed to assess the impact of the mechanical parameters of the strengthening systems in terms of strength. The results show that the strengthening systems play a fundamental role in terms of cross section capacity and, if not well designed, the strengthening systems may be ineffective or deleterious in cultural heritage

Tsunami risk communication and management: Contemporary gaps and challenges

Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures

Tsunami risk communication and management: Contemporary gaps and challenges

Very large tsunamis are associated with low probabilities of occurrence. In many parts of the world, these events have usually occurred in a distant time in the past. As a result, there is low risk perception and a lack of collective memories, making tsunami risk communication both challenging and complex. Furthermore, immense challenges lie ahead as population and risk exposure continue to increase in coastal areas. Through the last decades, tsunamis have caught coastal populations off-guard, providing evidence of lack of preparedness. Recent tsunamis, such as the Indian Ocean Tsunami in 2004, 2011 Tohoku and 2018 Palu, have shaped the way tsunami risk is perceived and acted upon. Based on lessons learned from a selection of past tsunami events, this paper aims to review the existing body of knowledge and the current challenges in tsunami risk communication, and to identify the gaps in the tsunami risk management methodologies. The important lessons provided by the past events call for strengthening community resilience and improvement in risk-informed actions and policy measures. This paper shows that research efforts related to tsunami risk communication remain fragmented. The analysis of tsunami risk together with a thorough understanding of risk communication gaps and challenges is indispensable towards developing and deploying comprehensive disaster risk reduction measures. Moving from a broad and interdisciplinary perspective, the paper suggests that probabilistic hazard and risk assessments could potentially contribute towards better science communication and improved planning and implementation of risk mitigation measures