Response of Organic Lime Mortars to Thermal and Electrical Shocks Due to Lightning Strikes
02 Sep 2020-Sustainability (Multidisciplinary Digital Publishing Institute)-Vol. 12, Iss: 17, pp 7181
TL;DR: In this article, the performance evaluation of green and low-cost mortars based on the use of organic additives was performed by using a mixture of organics (fig, jaggery, black grape, banana, kadukai).
Abstract: Lightning strikes are prevalent and inevitable natural phenomena that might cause damages during interaction with building structures and, in some cases, culminate in fires. During the last decades, several lightning strikes have caused considerable damages to cultural and heritage buildings. Furthermore, recent studies indicated a plausible connection between climate changes due to global warming and variations in the frequency and intensity of lightning. The evaluation of the structural efficiency and resilience of cultural buildings to global changes and natural risks appears significant in the light of the current scientific debate. This research aims at the assessment of lightning strikes’ effects on ancient heritage binding materials through the characterization of their thermal and electrical conductivity properties. This study focused on the performance evaluation of green and low-cost mortars based on the use of organic additives. Lime samples were reverse engineered by using a mixture of organics (fig, jaggery, black grape, banana, kadukai), which comprises the most common additives used in traditional Indian mortars. The reliability of the organic mixture in enhancing the resilience of masonry to lightning strikes was analyzed by using electromagnetic field simulation.
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TL;DR: The Special Issue on Risk Protection for Cultural Heritage and Historic Centres as mentioned in this paper reviewed the gaps in knowledge and practice related to disaster risk management of cultural heritage and highlighted specific issues that need to be addressed.
Abstract: This article introduces the Special Issue on Risk Protection for Cultural Heritage and Historic Centres. The article starts by reviewing the gaps in knowledge and practice related to disaster risk management of cultural heritage. It then reviews the contributions to the Special Issue, focussing on their multi-disciplinary findings that address some of the referred gaps. Finally, the article proceeds to discuss, in more detail, certain topics related to disaster risk management and cultural heritage that should be targeted by future research, emphasizing specific issues that need to be addressed.
13 citations
TL;DR: The Special Issue on Risk Protection for Cultural Heritage and Historic Centres as mentioned in this paper reviewed the gaps in knowledge and practice related to disaster risk management of cultural heritage and highlighted specific issues that need to be addressed.
Abstract: This article introduces the Special Issue on Risk Protection for Cultural Heritage and Historic Centres. The article starts by reviewing the gaps in knowledge and practice related to disaster risk management of cultural heritage. It then reviews the contributions to the Special Issue, focussing on their multi-disciplinary findings that address some of the referred gaps. Finally, the article proceeds to discuss, in more detail, certain topics related to disaster risk management and cultural heritage that should be targeted by future research, emphasizing specific issues that need to be addressed.
13 citations
TL;DR: In this article, the authors focused on analyzing lightning hazards to humans in the vicinity of heritage monuments in India and Sri Lanka and selected five monuments which include three giant stupas namely Ruwanweliseya, Jethawanaramaya and Abayagiriya from Sri Lanka.
Abstract: Lightning is one of the inevitable disastrous phenomena which in addition to damaging tall edifices, might also consequently endanger humans due to lightning-human interactions. This research focuses on analyzing lightning hazards to humans in the vicinity of heritage monuments in India and Sri Lanka. Five monuments which include three giant stupas namely Ruwanweliseya, Jethawanaramaya and Abayagiriya from Sri Lanka and two large temples namely Brihadishvara Temple and Gangaikonda Cholapuram from India have been chosen for investigation. Lightning-human interaction mechanisms namely direct strike, side flash, aborted upward leader, step and touch voltages have been investigated for the most onerous scenario on humans in the vicinity of the monuments. Firstly, the electro-geometric model as stipulated in standards has been implemented to ascertain the effectiveness of lightning protection to the structures. Subsequently, the study has been extended to the computation of step and touch voltages utilizing lightning current and electrostatic models based on Finite Element Method (FEM) using COMSOL Multi-physics®. Detailed plots of electric field and voltage distribution of lightning on humans due to a typical lightning current of 30 kA have been obtained. The final study involves assessment of current through humans which is estimated based on lumped R-C human model representation using OrCAD Cadence®. The analyses reveal that humans are invariably shielded against direct strikes whereas effects due to side flashes are minimal. During strikes to the monuments, high voltage may appear due to step and touch potential under dry conditions, though such effects could be mitigated by appropriate earthing system.
10 citations
TL;DR: In this paper , a fractal-based approach to the lightning protection of historical buildings and monuments against direct lightning flashes is introduced, based on a stochastic lightning attachment model that considers physical criteria on downward and upward leaders' inception and propagation.
Abstract: A fractal-based approach to the lightning protection of historical buildings and monuments against direct lightning flashes is introduced. The proposed methodology is based on a stochastic lightning attachment model that considers physical criteria on downward and upward leaders’ inception and propagation. The model foresees multiple competing upward leaders incepting from vulnerable points of the monument under protection and considers the branching and tortuous behavior of the lightning attachment phenomenon. Applying the proposed methodology to the Parthenon has shown that the risk of direct lightning flashes per year that cause physical damage to the monument is not acceptable without an external lightning protection system (LPS); two different LPSs are evaluated in terms of lightning interception efficiency. Lightning risk assessment results are discussed and compared with those obtained by implementing the procedures of the International Electrotechnical Commission (IEC) 62305.
7 citations
TL;DR: In this paper , a case study of the outer wall made of a one-floor building modeled as a rectangular plate with only one free edge and three clamped ones is presented, where the stability analysis of the sandwich wall is performed based on the application of artificial intelligence (AI) methods optimized with an innovative optimization approach.
Abstract: The present study is done to perform the optimal design of the structural components of the buildings against the unwanted wind load exerted on their outer face. To this end, the case study of the research is the outer wall made of a one-floor building modeled as a rectangular plate with only one free edge and three clamped ones. It is assumed that the wall is a sandwich plate whose core is made of auxetic material and dace-sheets are reinforced with nanoparticles of graphene platelets (GPL). Differential equations governing the system’s motion are obtained within the background of the plate’s shear-deformation theories. The stability analysis of the sandwich wall is performed based on the application of artificial intelligence (AI) methods optimized with an innovative optimization approach to gain a high level of accuracy. To determine the stability information of the system at the train points, the differential quadrature approach (DQA) is applied as the solver of differential equations of motion. The accuracy of the methods used in this paper is examined and verified by comparing the results with those acquired in the articles published previously. The results obtained in this study provide very useful information about the stability response of lightweight building components through AI-based solutions.
3 citations
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TL;DR: In this paper, the effect of silica fume (SF) and class C fly ash (FA) on the thermal conductivity of lightweight aggregate concrete (LWAC) was measured.
357 citations
TL;DR: In this paper, a general equation for predicting the thermal conductivity of concrete is proposed based on data reported by researchers, and the results indicate that most researchers have measured the k-value of cement-based materials based on transient methods.
Abstract: The thermal conductivity (k-value) of cement-based materials like concrete is an important factor when considering the amount of heat transfer through conduction. The amount of heat loss through walls and roofs has a direct effect on the energy consumption of buildings. The steady state and transient methods are considered the two main thermal conductivity measurement approaches. The moisture content, temperature, type of aggregate, type of cementitious material and density of concrete are influential factors on the thermal conductivity. The aim of this paper is to review the techniques most commonly used to measure the thermal conductivity of concrete as well as to consider the factors affecting the thermal conductivity of cement-based materials. In addition, a general equation for predicting the thermal conductivity of concrete is proposed in this study based on data reported by researchers. The results of this review indicate that most researchers have measured the k-value of cement-based materials based on transient methods. The reported k-value in saturated conditions is higher than in dry conditions. Moreover, the measured k-value exhibits a declining trend with increasing temperature. It is concluded that using lightweight concrete in structural and non-structural building envelopes is a valuable method of reducing the amount of heat transfer and energy consumption owing to the lower k-value of lightweight concrete compared to normal weight concrete.
353 citations
TL;DR: In this paper, a comparative study of various electrically conductive admixtures (discontinuous forms of steel and carbon) for lowering the electrical resistivity of cement is presented.
Abstract: Electrically conductive cement-based materials are useful for electrical grounding, lightning protection, resistance heating, static charge dissipation, electromagnetic interference (EMI) shielding, cathodic protection, and thermoelectric energy generation. The science and applications of electrically conductive cement-based materials are reviewed. In addition, a comparative study of the effectiveness of various electrically conductive admixtures (discontinuous forms of steel and carbon) for lowering the electrical resistivity of cement shows that the effectiveness decreases in the order: steel fibre of diameter 8 μm, steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, carbon nanofibre of diameter 0·1 μm, coke powder (< 75 μm) and graphite powder (< 1 μm). For EMI shielding, the effectiveness decreases in the order: steel fibre of diameter 8 μm, coke powder (< 75 μm), carbon nanofibre of diameter 0·1 μm, graphite powder (< 1 μm), steel fibre of diameter 60 μm, carbon fibre of diameter 15 μm, an...
147 citations