Search results

Transfer relations represent analytical solutions of the linear theory of circular arches, relating each one of the kinematic and static variables at an arbitrary cross-section to the kinematic and static variables at the initial cross-section. The purpose of this paper is to demonstrate the significance of the transfer relations for structural analysis by means of three examples taken from civil engineering.

The first example refers to an arch bridge, the second one to the vault of a metro station and the third one to a real-scale test of a segmental tunnel ring.

The main conclusions drawn from these three examples are as follows: increasing the number of hangers/columns of the investigated arch bridge entails a reduction of the maximum bending moment of the arch, allowing it to approach, as much as possible, the desired thrust-line behavior; compared to the conventional in situ cast method, a combined precast and in situ cast method results in a decrease of the maximum bending moment of an element of the vault of the studied underground station by 46%; and the local behavior of the joints governs both the structural convergences and the bearing capacity of the tested segmental tunnel ring.

The three examples underline that the transfer relations significantly facilitate computer-aided engineering of circular arch structures, including arch bridges, vaults of metro stations and segmental tunnel rings.

High packet error rates and variable link capacity due to harsh electric power system environments make reliable communication a challenging task for WSN in smart grid. Therefore, to increase network reliability and hence, to improve smart grid system performance, there is an urgent need for reliable communication protocols. The purpose of this paper is to propose an Adaptive Forward Error Correction (AFEC) mechanism for different smart grid environments, including 500 kV outdoor substation and underground transformer vaults, to address these challenges.

This paper presents the comparative performance evaluations of proposed AFEC mechanism for different smart grid environments. Simulation experiments have been performed by extending the ns‐2 network simulator. It also introduces existing and potential smart grid applications, research challenges, and opportunities of smart grid.

Comparative performance evaluations show that the proposed AFEC mechanism achieves high communications reliability without causing unnecessary network overhead. Also the advantages of existing smart grid applications have been presented.

The paper shows that high communications reliability without causing unnecessary network overhead has been achieved. Also comprehensive reviews of WSN smart grid applications have been presented.

Large displacement misalignment under the action of active faults can cause complex three-dimensional deformation in subway tunnels, resulting in severe damage, distortion and misalignment. There is no developed system of fortification and related codes to follow. There are scientific problems and technical challenges in this field that have never been encountered in past research and practices.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation based on the open-cut tunnel project of the Urumqi Rail Transit Line 2, which passes through the Jiujiawan normal fault. The test simulated the subway tunnel passing through the normal fault, which is inclined at 60°. This research compared and analyzed the differences in mechanical behavior between two types of lining section: the open-cut double-line box tunnel and the modified double-line box arch tunnel. The structural response and failure characteristics of the open-cut segmented lining of the tunnel under the stick-slip part of the normal fault were studied.

The results indicated that the double-line box arch tunnel improved the shear and longitudinal bending performance. Longitudinal cracks were mainly distributed in the baseplate, wall foot and arch foot, and the crack position was basically consistent with the longitudinal distribution of surrounding rock pressure. This indicated that the longitudinal cracks were due to the large local load of the cross-section of the structure, leading to an excessive local bending moment of the structure, which resulted in large eccentric failure of the lining and formation of longitudinal cracks. Compared with the ordinary box section tunnel, the improved double-line box arch tunnel significantly reduced the destroyed and damage areas of the hanging wall and footwall. The damage area and crack length were reduced by 39 and 59.3%, respectively. This indicates that the improved double-line box arch tunnel had good anti-sliding performance.

This paper adopted a self-designed large-scale active fault dislocation simulation loading system to conduct a similar model test of the tunnel under active fault dislocation. This system increased the similarity ratio of the test model, improved the dislocation loading rate and optimized the simulation scheme of the segmented flexible lining and other key factors affecting the test. It is of great scientific significance and engineering value to investigate the structure of subway tunnels under active fault misalignment, to study its force characteristics and damage modes, and to provide a technical reserve for the design and construction of subway tunnels through active faults.

Although cathedrals represent arguably the greatest contribution to our architectural heritage there is no legislation which controls measures to protect them from fire. Since the major fire at York Minster in 1984 the many cathedral authorities have undertaken varying amounts of work to prevent a similar tragedy, but there remain unprotected cathedrals and no consensus on further progress. Addresses the complex nature of cathedral buildings in fire safety terms along with the conflict inherent in introducing modern protective measures in structures of enormous historic and aesthetic quality. Examines data held by the leading insurer of cathedrals in England and Wales, the Ecclesiastical Insurance Group, and sets it alongside the authors′ own research to reveal a picture of great variation in methods and measures of fire protection, and a sense of the changes which are underway or can be expected in coming years. At a time when grant aid for English cathedrals has become available and may soon be extended to cover fire safety measures, provides timely information on financial issues, technical difficulties and fire management policies which lie at the centre of debate, and considers some of the issues which must be addressed.

The Corporation of the City of London are about to appoint a Public Analyst, and by advertisement have invited applications for the post. It is obviously desirable that the person appointed to this office should not only possess the usual professional qualifications, but that he should be a scientific man of high standing and of good repute, whose name would afford a guarantee of thoroughness and reliability in regard to the work entrusted to him, and whose opinion would carry weight and command respect. Far from being of a nature to attract a man of this stamp, the terms and conditions attaching to the office as set forth in the advertisement above referred to are such that no self‐respecting member of the analytical profession, and most certainly no leading member of it, could possibly accept them. It is simply pitiable that the Corporation of the City of London should offer terms, and make conditions in connection with them, which no scientific analyst could agree to without disgracing himself and degrading his profession. The offer of such terms, in fact, amounts to a gross insult to the whole body of members of that profession, and is excusable only—if excusable at all—on the score of utter ignorance as to the character of the work required to be done, and as to the nature of the qualifications and attainments of the scientific experts who are called upon to do it. In the analytical profession, as in every other profession, there are men who, under the pressure of necessity, are compelled to accept almost any remuneration that they can get, and several of these poorer, and therefore weaker, brethren will, of course, become candidates for the City appointment.

Islands have long been discussed as refuges from global catastrophes; this paper will evaluate them systematically, discussing both the positives and negatives of islands as refuges. There are examples of isolated human communities surviving for thousands of years on places like Easter Island. Islands could provide protection against many low-level risks, notably including bio-risks. However, they are vulnerable to tsunamis, bird-transmitted diseases and other risks. This paper aims to explore how to use the advantages of islands for survival during global catastrophes.

Preliminary horizon scanning based on the application of the research principles established in the previous global catastrophic literature.

The large number of islands on Earth, and their diverse conditions, increase the chance that one of them will provide protection from a catastrophe. Additionally, this protection could be increased if an island was used as a base for a nuclear submarine refuge combined with underground bunkers and/or extremely long-term data storage. The requirements for survival on islands, their vulnerabilities and ways to mitigate and adapt to risks are explored. Several existing islands, suitable for the survival of different types of risk, timing and budgets, are examined. Islands suitable for different types of refuges and other island-like options that could also provide protection are also discussed.

The possible use of islands as refuges from social collapse and existential risks has not been previously examined systematically. This paper contributes to the expanding research on survival scenarios.

In November 2001, Scott Carlson, in the Chronicle of Higher Education wrote an article on library use titled “The deserted library: As students work online, reading rooms empty out—leading some campuses to add Starbucks” (Carlson, 2001). The essence of this chapter is that many librarians, facing dramatic declines in library gate counts resulting from the wealth of electronic resources accessible remotely, were beginning to move away from traditional conceptions of the library as primarily a repository for print collections. Carlson describes the “tough sell” that the Georgia College and State University in Milledgeville had experienced when planning a $19.5 million library addition in the mid-1990s. In response librarians had begun “fighting back” with “plush chairs, double-mocha lattes, book groups, author readings.” Still, no one knew whether these stratagems would enhance learning or bring its readers back.

A MAJOR transport problem is the rush‐hour traffic. On London's Underground, the morning and more particularly the evening rush‐hour crowds are dense and unless officials at a station are aware of, or can anticipate, the position at any time the situation can arise where departures of trains are delayed and time‐tables are upset.

This paper aims to contribute to the discussion of the experimental campaigns on Cultural Heritage buildings. By adopting integrated procedures it is possible to limit the invasiveness of the destructive techniques leading to reliable results. The purpose is the proper definition of the structural system, which represents the starting point of the following analysis's phases, not treated in this work. A methodology based on normative references and acknowledged non-destructive and partial destructive strategies has been conceived. The latter aims to an accurate comprehension of the structural information.

An integrated approach for the structural assessment of cultural heritage buildings is presented. The methodology defines an interdisciplinary procedure based on normative references, non-destructive and minor-destructive techniques. A funnel-shaped workflow is developed to characterize the structural system of the buildings. The non-destructive campaigns are widely extended. Then, in-depth analysis concerning partial demolitions and minor-destructive tests are performed. The dynamic identification of the building is executed to detect its global response. The final validation of the assumed mechanical values is obtained by comparing the experimental modes coming from the ambient vibrations and the analytical modes of the structural modelling.

This research belongs to the Protocol signed between the Municipality of Florence and Department of Earth's Science and Department of Architecture of the University of Florence for the seismic vulnerability assessment of relevant and strategic buildings.

The descripted methodology is targeted for monuments and special buildings where the use of destructive techniques is not possible or unrecommended.

Social implications are related to the conservation of Heritage buildings. The latter deals with: (1) risk assessment of the targeted buildings towards different hazard sources (e.g. earthquakes, floods); (2) knowledge path developed through non-invasive diagnostic campaigns oriented to the conservation of the manufact. Furthermore, the paper encourages towards the recognition of non-destructive techniques and ambient vibration tests for the achievement of higher knowledge levels.

This paper defines a funnel-shaped procedure defining hierarchical roles between the different available strategies. The originality of this contribution is firstly related to the methodological flowchart. It is targeted to limit the invasive tests and consequently achieving accurate levels of knowledge. Secondly, some novelty can be found in the adoption of improvement parameters from a regional database adopting a Bayesian approach.

Some lessons learned from post‐earthquake damage survey of structures affected by the Bam earthquake of December 26, 2003 in Iran are encapsulated in this paper. The Bam earthquake caused catastrophic structural damage in the region.

A method similar to that of rapid evaluation procedure (REP), recommended by the Applied Technology Council (ATC‐20) in the USA, was used for damage survey.

Bam represents a typical ancient city in many countries around the world. Most of the structures in the region are made of adobe, unreinforced masonry, steel, and unreinforced/reinforced concrete. Some of the main types of structural damage, their causes, and potential remedial measures are characterized with an emphasis on the very basic fundamental principles of earthquake‐resistant design.

The research reported has considerable implications for other seismic‐affected regions of the world.

A first hand‐account of the catastrophic damage caused by this natural disaster and the implications for future design and construction in seismic‐affected areas.