Past earthquake disasters in Greece, during the last thirty years, demonstrate that the severity of destruction is not only due to the intensity of the seismic event but also to the urbanization of the affected region...Past earthquake disasters in Greece, during the last thirty years, demonstrate that the severity of destruction is not only due to the intensity of the seismic event but also to the urbanization of the affected region and the vulnerability of certain types of buildings. Considerable damage was sustained by both old unreinforced masonry structures as well as by relatively new multistory reinforced concrete structures with ＂soft story＂ at their ground floor level. The most important observations made during six past earthquake disasters are presented in a summary form and discussed. The most remarkable case of extensive structural damage was caused from the resent Athens 1999 earthquake. The consequent discussion focuses on the following issues： （1） Classification of structural damage and their underlying causes. （2） Repair and strengthening of damaged structures. （3） Upgrade the seismic design. （4） Plans for earthquake preparedness. （5） Assessing the vulnerability of certain type of structures （schools, hospitals, public buildings etc）. （6） Education specialized in earthquake engineering. （7） The enrichment of the strong motion data base.展开更多
In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process ...In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.展开更多
The Italian earthquakes of recent decades created an emergency situation that required immediate post-earthquake reconstruction policies, which led to an increase in the demand for construction minerals. In particular...The Italian earthquakes of recent decades created an emergency situation that required immediate post-earthquake reconstruction policies, which led to an increase in the demand for construction minerals. In particular, extraction in active quarries has been intensified, and new quarries opened according to extraordinary procedures notwithstanding current regulations. The objective of this work is to investigate the consequences that a seismic event may produce on both the built-up environment, i.e. the totality of urban and suburban settlements and infrastructure, and the natural environment, which is often compromised by hasty emergency procedures aimed at mineral extraction. As a result, correct evaluation of the demand for minerals and the recycling of earthquake debris are the fundamental elements of coherent post seismic reconstruction, by means of which post-earthquake policies could be reconciled with environmental protection.展开更多
The feasibility analysis of projects for the preservation of the historical heritage buildings is an important problem concerning the evaluation of ＂the total cost of intervention＂, which includes all the future dam...The feasibility analysis of projects for the preservation of the historical heritage buildings is an important problem concerning the evaluation of ＂the total cost of intervention＂, which includes all the future damage costs. The total cost of intervention represents a suitable measure of the expected deterioration risk and its evolution obviously depends on the damage process which buildings are subjected to. That damage phenomena affecting masonry buildings pleased into an aggressive environment are suitably modelled by renewal processes： this happens both in the case of catastrophic events, or in the case of the so-called ＂natural aging＂, in which damage comes off gradually in time. In the hypothesis ofa Markovian renewal process （Mrp） describing the damage process, the total cost of all the future damage is evaluated taking into account both the damage aspects： damages due to catastrophic aspects and damages due to aggressive environment, supposing different maintenance and/or rehabilitation scenarios. A semi-Markov process （s-Mp） is defined to model the damage rehabilitation history of buildings in presence of seismic events, natural ageing and rehabilitation strategies. The expected rewards connected to the process are defined; they represent a significant measure of the risk.展开更多
This article questions the reliability of the amount of revenue recognized in the percentage of completion （POC） method of revenue recognition in construction industry and recommends a new method based on the progre...This article questions the reliability of the amount of revenue recognized in the percentage of completion （POC） method of revenue recognition in construction industry and recommends a new method based on the progress billing which is more reliable. The most commonly used method of revenue recognition in the construction industry is the percentage of completion method （POC）, where the revenue is recognized on the basis of the percentage of work completed. The calculation of percentage of work completed is made on the basis of the cost incurred for the contract work during the financial period and the cost required for completion of the work as estimated by the contractor. Here, the acceptance of the product by the buyer （contractee） is not involved in recognizing the revenue. The reliability of the amount of revenue and its collectability can be assured only when the buyer accepts the product. The approval of the progress bill by the contractee is needed to assure the reliability and collectability and it must be the event that triggers the recognition of revenue.展开更多
The preservation of historical and cultural heritage from seismic risk is a question of interest in Italy. However, too little has been done to deal with this problem. First of all, the seismic safety of cultural heri...The preservation of historical and cultural heritage from seismic risk is a question of interest in Italy. However, too little has been done to deal with this problem. First of all, the seismic safety of cultural heritage should be a topic of prevention. The research described in the paper presents a multi-approach procedure to address risk assessment of large-scale urban systems with the aim to contribute at the development of risk mitigation policies for historical centers buildings. The observation of the earthquakes effects in Italy clearly highlights the role of the high vulnerability of the existing building on the consequences in terms of casualties and damage, rather than the severity of seismic events, especially in historical contexts. Unlike the new buildings which should be planned and designed to respect seismic safety requirements, existing buildings require a careful safety assessment on the basis of their susceptibility to damage which depends on building techniques, past damage events, maintenance, changes, etc.展开更多
文摘Past earthquake disasters in Greece, during the last thirty years, demonstrate that the severity of destruction is not only due to the intensity of the seismic event but also to the urbanization of the affected region and the vulnerability of certain types of buildings. Considerable damage was sustained by both old unreinforced masonry structures as well as by relatively new multistory reinforced concrete structures with ＂soft story＂ at their ground floor level. The most important observations made during six past earthquake disasters are presented in a summary form and discussed. The most remarkable case of extensive structural damage was caused from the resent Athens 1999 earthquake. The consequent discussion focuses on the following issues： （1） Classification of structural damage and their underlying causes. （2） Repair and strengthening of damaged structures. （3） Upgrade the seismic design. （4） Plans for earthquake preparedness. （5） Assessing the vulnerability of certain type of structures （schools, hospitals, public buildings etc）. （6） Education specialized in earthquake engineering. （7） The enrichment of the strong motion data base.
基金supported by the Specific Research of China Institute of Water Resources and Hydropower Research (Grant Nos. Fangji 1240)Chinese Ministry of Water Resources (Grant Nos. 201301058 and 20131059)the Basic Research Fund for Central Public Research Institutes (Grant No. CKSF2015010/TB)
文摘In recent years, flash flood disasters have occurred frequently in southwest China due to the increased frequency of extreme climate events. To solve this problem, great efforts have been made in studying the process of flash flood. However, little attention was paid on bearing body of hazard, the clusters of buildings. Thus the real disaster mechanism of flash flood remains unclear.Accordingly, based on the experiments of artificial flash floods in a conceptual solid model, this paper focuses on the flood-impacted inundation characteristics of the building clusters at different locations of the gully model, in order to obtain a better understanding of the disaster process and the interaction between the flash floods and building clusters. The results showed that, in a typical smallscale flash flood gully with hot and dry climate, 1)clusters of buildings on an alluvial fan could reduce about 35% of the flooding area by blocking the diffusion of the flood to the depression areas, and could also promote the deposition in lower reaches of the river channel by blocking the overbank flow from going back into the channel, making the width-depth ratio of the channel larger. 2) The flash flood rates of disaster and hazard on the alluvial fan are generally higher than that of the inner gully. For the inner gully,buildings located on the beaches along the lower river and the transitional areas of the straight channel and channel bends can easily be affected because of their lower elevations. For the alluvial fan, buildings nearby the meanders suffer the greatest impacts because of bank collapsing and flooding. 3) The safe vertical distance from a building to the river channel is 13 m for the buildings in the inner gully under extreme floods. Below this threshold, the smaller the vertical distance is, the greater the risk exposure is. For the buildings on the alluvial fan, especially for the buildings near the concave bank of the top rush point,the horizontal distance is more important, and the safe value is 80 m under extreme floods.
文摘The Italian earthquakes of recent decades created an emergency situation that required immediate post-earthquake reconstruction policies, which led to an increase in the demand for construction minerals. In particular, extraction in active quarries has been intensified, and new quarries opened according to extraordinary procedures notwithstanding current regulations. The objective of this work is to investigate the consequences that a seismic event may produce on both the built-up environment, i.e. the totality of urban and suburban settlements and infrastructure, and the natural environment, which is often compromised by hasty emergency procedures aimed at mineral extraction. As a result, correct evaluation of the demand for minerals and the recycling of earthquake debris are the fundamental elements of coherent post seismic reconstruction, by means of which post-earthquake policies could be reconciled with environmental protection.
文摘The feasibility analysis of projects for the preservation of the historical heritage buildings is an important problem concerning the evaluation of ＂the total cost of intervention＂, which includes all the future damage costs. The total cost of intervention represents a suitable measure of the expected deterioration risk and its evolution obviously depends on the damage process which buildings are subjected to. That damage phenomena affecting masonry buildings pleased into an aggressive environment are suitably modelled by renewal processes： this happens both in the case of catastrophic events, or in the case of the so-called ＂natural aging＂, in which damage comes off gradually in time. In the hypothesis ofa Markovian renewal process （Mrp） describing the damage process, the total cost of all the future damage is evaluated taking into account both the damage aspects： damages due to catastrophic aspects and damages due to aggressive environment, supposing different maintenance and/or rehabilitation scenarios. A semi-Markov process （s-Mp） is defined to model the damage rehabilitation history of buildings in presence of seismic events, natural ageing and rehabilitation strategies. The expected rewards connected to the process are defined; they represent a significant measure of the risk.
文摘This article questions the reliability of the amount of revenue recognized in the percentage of completion （POC） method of revenue recognition in construction industry and recommends a new method based on the progress billing which is more reliable. The most commonly used method of revenue recognition in the construction industry is the percentage of completion method （POC）, where the revenue is recognized on the basis of the percentage of work completed. The calculation of percentage of work completed is made on the basis of the cost incurred for the contract work during the financial period and the cost required for completion of the work as estimated by the contractor. Here, the acceptance of the product by the buyer （contractee） is not involved in recognizing the revenue. The reliability of the amount of revenue and its collectability can be assured only when the buyer accepts the product. The approval of the progress bill by the contractee is needed to assure the reliability and collectability and it must be the event that triggers the recognition of revenue.
文摘The preservation of historical and cultural heritage from seismic risk is a question of interest in Italy. However, too little has been done to deal with this problem. First of all, the seismic safety of cultural heritage should be a topic of prevention. The research described in the paper presents a multi-approach procedure to address risk assessment of large-scale urban systems with the aim to contribute at the development of risk mitigation policies for historical centers buildings. The observation of the earthquakes effects in Italy clearly highlights the role of the high vulnerability of the existing building on the consequences in terms of casualties and damage, rather than the severity of seismic events, especially in historical contexts. Unlike the new buildings which should be planned and designed to respect seismic safety requirements, existing buildings require a careful safety assessment on the basis of their susceptibility to damage which depends on building techniques, past damage events, maintenance, changes, etc.
