bluuebunny/crossref_metadata_2025 huggingface dataset:
Cost-Benefit Analysis of Three-Dimensional Craniofacial Models for Midfacial Distraction: a Pilot Study
Authors: Rogers-Vizena Carolyn R. , Flath Sporn Susan , Daniels Kimberly M. , Padwa Bonnie L. , Weinstock Peter
Published: August 2016

Objective

Patient-specific three-dimensional (3D) models are increasingly used to virtually plan rare surgical procedures, providing opportunity for preoperative preparation, better understanding of individual anatomy, and implant prefabrication. The purpose of this study was to assess the benefit of 3D models related to patient safety, operative time, and cost.

Design

Retrospective review.

Setting

Academic, tertiary care hospital.

Patients, Participants

Midfacial distraction was studied as a representative craniofacial operation. A consecutive series of 29 patients who underwent a single type of midfacial distraction was included.

Intervention

For a subset of patients, computed tomography-derived 3D models were used to study patient-specific anatomy and precontour hardware.

Main Outcome Measures

Complications, operative time, blood loss, and estimated cost.

Results

Twenty patients underwent midfacial distraction without and nine with preoperative use of a 3D model. Seven complications occurred in six patients without model use, including premature consolidation (3), cerebrospinal fluid leak (2), and hardware malfunction (2). No complications were reported in the model group. Controlling for surgeon variation, model use resulted in a 31.3-minute (7.8%) reduction in operative time. Time-based cost savings were estimated to be $1036.

Conclusions

Three-dimensional models are valuable for preoperative planning and hardware precontouring in craniofacial surgery, with potential positive effects on complications and operative time. Savings related to operative time and complications may offset much of the cost of the model.
Is Salvage Liver Resection Necessary for Initially Unresectable Hepatocellular Carcinoma Patients Downstaged by Transarterial Chemoembolization? Ten Years of Experience
Authors: Zhang Yingqiang , Huang Guihua , Wang Yu , Liang Lijian , Peng Baogang , Fan Wenzhe , Yang Jianyong , Huang Yonghui , Yao Wang , Li Jiaping
Published: August 2016

Introduction.

This study evaluated long-term outcomes of salvage surgery as additional therapy following downstaging of hepatocellular carcinoma (HCC) with transarterial chemoembolization (TACE) in patients with initially unresectable HCC.

Methods.

A retrospective analysis was performed of 831 consecutive patients with unresectable HCC who underwent TACE as initial treatment between June 2004 and December 2014. Of these, 82 patients with downstaged resectable HCC were enrolled in this study: 43 received salvage surgery (S group) and the remaining 39, who refused salvage resection, were the control group (T group). The primary endpoint was overall survival (OS).

Results.

The median OS in the S and T groups was 49 and 31 months, respectively (p = .027). The 2-, 4-, and 5-year survival rates were 93%, 47%, and 26% in the S group and 74%, 18%, and 10% in the T group, respectively (p = .019). Treatment modality (hazard ratio [HR], 0.337; 95% confidential interval [CI], 0.184–0.616; p < .001) and response to TACE (complete vs. partial; HR, 3.154; 95% CI, 1.709–5.822; p < .001) were independent prognostic factors for survival. The median OS for patients in the complete response and partial response (PR) subgroups was 50 and 49 months, respectively, in the S group and 54 and 24 months, respectively, in the T group (p = .699 and p < .001, respectively). The median OS for HCC patients with macroscopic vascular invasion (MVI) was 58 and 30 months in the S and T groups, respectively (p = .024).

Conclusion.

Salvage surgery after downstaging of unresectable HCC had a survival benefit only for patients with MVI or a PR to TACE.
Delivering London 2012: procurement
Authors: Cornelius Mike , Fernau John , Dickinson Paul , Stuart Morag
Published: August 2016

The fundamental aims of the Olympic Delivery Authority's procurement team were to deliver the required London 2012 contracts in time for construction to be completed by July 2011, and to implement policy objectives. This paper explains how venue-clusters and pan-venue packages were used to centralise the supply of commodities and support policy objectives. It also reports how the NEC3 suite of contracts was selected and amended to reflect delivery obligations and brand restrictions, and how the contracts worked in practice.
Global research continues into strengthening structures against earthquakes
Authors: Adam Jose
Published: August 2016

Earthquakes continue to shatter buildings and the people inside them. Jose Adam and Francisco Pallarés of Universitat Politècnica de València report on recent trends in seismic strengthening of building structures.
Pipe–soil interaction during pipe jacking
Authors: Milligan G. W. E. , Norris P.
Published: August 2016

The purpose of this paper is to introduce some simple theoretical models of pipe--soil interaction during pipe jacking, and relate these to observations made in the field. Ground conditions, construction techniques and the degree of site control all influence the resistance to jacking of pipes, but if an appropriate model is chosen it should be possible to predict jacking forces with a reasonable degree of accuracy. Deviations of the pipeline from a straight line increase the jacking resistance. A new analysis, based on observations from the field monitoring, provides an explanation for the measured increases in pipeline resistance for pipes jacked through a stable bore; it highlights the important factors and emphasizes the need for careful control of pipeline alignment. Explanations are also sought for the apparently frictional behaviour in terms of total stress at the pipe–soil interface in firm and stiff cohesive soils. Time effects are shown to be important in high plasticity clays.
An automated electrolevel deformation monitoring system for tunnels
Authors: Bassett R. H. , Kimmance J. P. , Rasmussen C.
Published: August 2016

A newly developed deformation monitoring system comprising electrolevels mounted on a ring of interconnected beams has undergone field trials and further development in a London Underground Ltd running tunnel, prior to its installation in existing tunnels requiring deformation monitoring during construction of the Jubilee Line Extension Project. The system, its mechanics and the geometric principles upon which it functions are described. Details are given of the performance of the system and the measurements made. It is shown that the system is minimally intrusive, enabling continuous monitoring of operational tunnels, and is sufficiently sensitive to detect small cyclical displacements which may correlate to the tidal effects of the River Thames while remaining sufficiently robust to effects of temperature, vibration and dust.
Leachate generation in landfills in semi-arid climates
Authors: Blight G. E. , Fourie A. B.
Published: August 2016

The very severe requirements for landfill underliners and leachate management systems that were prevalent in the early 1990s appear to be giving way to a more moderate view of the potential interaction between a landfill and its receiving environment. In particular, if it can be shown that a landfill will not represent a serious threat of harm to the environment, more recent sets of landfilling guidelines and proposed regulations relax the requirements for underliners and leachate management. This paper considers the characteristics of a landfill water balance in arid and semi-arid climatic conditions and then gives examples of landfills that produce very little leachate and those that produce no significant leachate. The influence of the field moisture capacity of a landfill in limiting leachate production is emphasized. On the basis of the available evidence, relaxation of standards for underliners and leachate collection systems can be fully justified in arid regions and many semi-arid regions.
Re-engineering humanitarian response – opportunity and obligation
Authors: Lee Chris , Potangaroa Regan
Published: August 2016

The existing international humanitarian system, with its focus on United Nations agencies and large international non-government organisations, is no longer fit for purpose. The extent of humanitarian need already exceeds the available donor funds, and the situation will likely worsen as needs increase and donors face competing domestic priorities. A new approach, which can deliver substantially greater humanitarian effect for effort, is thus needed. Virtually all the goods and many of the services provided at the front line of an emergency come from commercial private-sector enterprises. A much higher level of technical and managerial professionalism is needed to ensure that these private-sector resources are mobilised, directed and supervised to achieve fast, efficient and effective response. Civil engineers have a vital role to play – they have skills and attitudes that are critically lacking within the current system. This provides both opportunity and obligation for those able to contribute.
Building to beat Ebola: the Royal Engineers in Sierra Leone
Authors: Francis Nick
Published: August 2016

The 2014 Ebola outbreak in west Africa raised fears of a global pandemic. Specialists from the UK Corps of Royal Engineers were deployed to Sierra Leone to design and construct emergency treatment units, in support of the UK Department for International Development. Whereas projects of this scale typically take several years to plan and deliver, the exponential spread of the disease required that the design, tender and construction programmes were extraordinarily accelerated. Extensive innovation and gruelling programmes ensured that all six treatment units were open and receiving patients within 3 months. This paper outlines the clinical principles underpinning the design of Ebola treatment facilities and chronicles the experience of running multiple major construction sites simultaneously in the developing world during a humanitarian disaster.
Delivering the Cheung Chau submarine pipeline in Hong Kong using NEC3
Authors: Li Dennis , Lo Warren , Shou Stephanus
Published: August 2016

The Cheung Chau submarine pipeline between Hong Kong’s Lantau and Cheung Chau islands is a 1·4 km long, 500 mm diameter water main installed by horizontal directional drilling. It is one of the largest trenchless pipeline projects undertaken in Hong Kong. Drilling through a variety of rock strata up to 100 m below sea level was inherently risky, so use of an appropriate procurement strategy was pivotal to controlling costs and ensuring successful delivery. The government’s Water Supplies Department opted to adopt the Institution of Civil Engineers’ NEC3 Engineering and Construction Contract for the project. This paper describes the scope of the work, how an appropriate contract strategy was chosen and how NEC3 facilitated effective risk management during construction. It concludes with a recommendation that NEC3 brings valuable benefits and is suitable for use in future similar projects.
Reference class forecasting for Hong Kong’s major roadworks projects
Authors: Flyvbjerg Bent , Hon Chi-keung , Fok Wing Huen
Published: August 2016

Reference class forecasting is a method to remove optimism bias and strategic misrepresentation in infrastructure projects and programmes. In 2012 the Hong Kong government’s Development Bureau commissioned a feasibility study on reference class forecasting in Hong Kong – a first for the Asia-Pacific region. This study involved 25 roadwork projects, for which forecast costs and durations were compared with actual outcomes. The analysis established and verified the statistical distribution of the forecast accuracy at various stages of project development, and benchmarked the projects against a sample of 863 similar projects. The study contributed to the understanding of how to improve forecasts by de-biasing early estimates, explicitly considering the risk appetite of decision makers, and safeguarding public funding allocation by balancing exceedance and under-use of project budgets.
Kai Tak cruise terminal, Hong Kong: a sustainable development
Authors: Wong Jacky , Chin Sai Ping , Ramanathan Muthukaruppan
Published: August 2016

The new Kai Tak cruise terminal building in Hong Kong is sited on the picturesque reclaimed site of the city’s former airport runway. Completed in 2013, the three-storey structure is made of a series of long-span bridge-like post-tensioned main box beams, which in turn support precast post-tensioned secondary beams. As described in this paper, the extensive use of precast and bridge erection methods enabled fast-track construction, such that the whole project was designed and built in 36 months. The multiple-use building design also adopted a ‘3S’ concept of standardisation, simplification and single integrated elements. The landscaped roof deck contributes to the ecology of the area, and a 25% energy reduction was achieved by allowing natural daylight and natural ventilation into the interior, using a photovoltaic system to generate power and installing a solar hot-water system.
Moving infrastructure benefits beyond projects and programmes
Authors: Blom Carron , Guthrie Peter
Published: August 2016

Recent research confirms the growing limitation of infrastructure projects and programmes to deliver long-term benefits to society. A more holistic, system-level approach to infrastructure delivery and management is needed, say Carron Blom and Peter Guthrie from the University of Cambridge.
Model tests of soil heave plug formation in suction caisson
Authors: Guo Wei , Chu Jian , Kou Hailei
Published: August 2016

An experimental study of the formation of the soil heave plug inside a concrete caisson during installation in clay under suction is presented. The soil heave plug, the amount of caisson penetration and the vacuum pressure applied were measured during the model tests. The results show that the soil heave plug can completely fill in the cavity and prevent the caisson from penetrating further. The soil heave plug is affected by the geometry of the caisson. The higher the consolidation stress or the stiffer the soils, the higher is the suction pressure required, and a higher suction will in turn induce a greater soil heave plug. The m value, defined as the ratio of the volume of the soil heave plug to that of the penetrated caisson skirt wall, is adopted to evaluate the soil heave plug. The relationship between the m value and the undrained shear strength of the soil can be used to estimate the amount of soil heave plug and the caisson penetration for a concrete caisson with a wall thickness to external diameter ratio of 5% in normally consolidated clay conditions.
Pile tests to justify higher adhesion factors in London Clay
Authors: Martin Jim , Budden David , Norman Stuart
Published: August 2016

The London District Surveyors Association guidance notes for the design of straight shafted bored piles in London Clay recommend an adhesion factor of 0·5 for shaft friction pile design. This value, based on the back-analysis of many maintained load pile tests to failure in London Clay, was selected to cover all design scenarios irrespective of site location, pile construction method, pile geometry and whether or not pile load testing is carried out. This ‘one size fits all’ approach to pile design is potentially over conservative. For sites where maintained load tests (MLTs) to failure on representative preliminary test piles are carried out, the results can be back-analysed to determine the appropriate adhesion factor for the site, which may then be used to improve the efficiency of the pile design. This paper discusses the pile design philosophy, pile load testing and construction sequence for a large development in Whitechapel, London, where MLT results were used to justify an increased adhesion factor of 0·6. This increased adhesion factor ensured that piles were ‘dry’ bored and founded above the water-bearing strata of the Lambeth Group, leading to lower project costs and risks.
The boundary between deep foundations and ground improvement
Authors: Hamidi Babak , Masse Frederic , Racinais Jerome , Varaksin Serge
Published: August 2016

Deep foundations by implementation of piles have been the historical and conventional solution for supporting heavy loads in low-strength or highly compressible soils. During recent decades, however, ground improvement has successfully been able to provide competitive and economical technical foundation solutions by increasing the ground's mechanical properties, thereby increasing bearing capacity and reducing total, differential and creep settlements. Controlled modulus columns are formed by installing cementitious columnar rigid inclusions into soft ground, and can be considered as the boundary between the classical deep foundations and ground improvement technologies. These elements have a pile-like appearance, but are designed as ground improvement inclusions. This paper discusses the concept of the controlled modulus column, its design philosophy and the way it behaves; a case study of the world record for depth of a controlled modulus column installation is also presented to demonstrate its application.
Modelling ground vibrations induced by harmonic loads
Authors: Hamdan Nawras , Laghrouche Omar , Connolly David , Woodward Peter K.
Published: August 2016

A finite-element model combining the frequency domain thin-layer method with paraxial boundary conditions to simulate the semi-infinite extent of a soil medium is presented in this paper. The combined numerical model is used to deal with harmonic vibrations of surface rigid foundations on non-horizontal soil profiles. The model can deal with soil media over rigid bedrock or significant depths of half-space. Structured finite elements are used to mesh simple geometry soil domains, whereas unstructured triangular mesh grids are employed to deal with complex geometry problems. Dynamic responses of homogeneous as well as layered soil profiles are simulated and validated against analytical and approximate solutions. Finally, the model is used to deal with surface ground vibration reduction, in which it is first validated against published results and then followed by an example involving a bridge.
Construction and testing of self-drilled soil nails
Authors: Mickovski Slobodan B. , Lindsay Fraser M. , Smith Martyn J.
Published: August 2016

Current standards and best practice guidance recognise that testing of self-drilled hollow bar soil nails can be problematic as conventional packers and debonded lengths cannot be constructed. As a result, this causes difficulty in testing and confirming the ultimate bond resistance within the passive zone of a soil-nailed slope, and thus the design soil nail lengths. This paper provides a summary and review of the various testing procedures adopted for a soil nail construction project in Scotland. The practical design considerations, and their validation through the installation and testing of 49 sacrificial test nails, are detailed. The construction issues associated with the nail installation and testing are also outlined and discussed in light of the results obtained using different testing approaches. The aim of this case study is to report on the experiences with installation and testing of hollow bar soil nails. The objectives are to develop an initial data base of available soil–grout bond strength of hollow bar soil nails based on the several practical installation procedures used in this project and to establish areas for improvement of installation, testing and quality control in order to perform comparable pullout tests on self-drilled hollow bar soil nails.
Failure analysis of an infinite unsaturated soil slope
Authors: Zhou Annan , Li Chun-Qing , Huang Jinsong
Published: August 2016

Increases in rainfall and groundwater level rising can cause more frequent failures of unsaturated soil slopes, resulting in large-scale landslides. The aim of this paper is to propose a methodology for prediction of the failure of an infinite soil slope subject to steady unsaturated flow conditions. Probabilistic models for soil porosity, friction angle, matric suction and saturation are developed. The probability of slope failure for different groundwater levels and infiltration (or evaporation) intensities is investigated. Numerical results show that, for a slope with deep groundwater, the slope failure is mainly controlled by the rainfall infiltration, whereas for shallow groundwater, the slope failure is governed by the location of the groundwater level. A merit of the proposed methodology is that the fluctuation of the soil porosity along the depth of a slope is modelled as a Gaussian random field. The paper concludes that the proposed methodology can be used for prediction of slope failures under steady unsaturated flow conditions. Accurate prediction of slope failures can prevent catastrophic consequences of landslides.
Natural disasters: an engineer's perspective in Nepal
Authors: Merrilees Kirsteen
Published: August 2016

In 2011 an earthquake measuring 6.9 on the Richter scale occurred on the border of Nepal and Sikkim. This sparked a flurry of interest in improving Nepal's resilience to disasters. In April 2015, numerous large earthquakes were experienced throughout central Nepal. The impact of earthquakes in Nepal is exacerbated by poor quality structures, poor public infrastructure, extreme poverty and a lack of access to the worst affected areas, making the country extremely vulnerable to earthquakes and a range of other natural disasters including landslides, flooding, fires – all of which kill hundreds of people each year. The role of engineers in helping governments and local communities prepare for, mitigate and recover from these disasters is a critical aspect of the national strategy for disaster risk management. Significant progress is being made in raising the profile of resilience and the role of engineers. The efforts of the engineering community in the immediate aftermath of the 2015 earthquake resulted in unprecedented positive messages in the Nepal media on the role of engineers. With initiatives in motion to improve engineering practice, the time is ripe for the Nepali engineering community to influence government and the construction sector to improve the country's resilience to natural disasters.
Decisions on quality assurance criteria of recreational beaches
Authors: Guneroglu Nilgun , Ozdemir Unal , Guneroglu Abdulaziz
Published: August 2016

Coastal management of recreational beaches is an important topic that needs to use scientific approaches when decisions have to be taken by an authority or a stakeholder. Coastal recreation, which mainly depends on tourism activities, is strongly linked to the management perspective of a region which is generally the municipal authorities in Turkey. Therefore, reliable quantitative management strategies become an issue of high priority in the management of recreational beaches. In this study, the problem of beach quality assurance criteria was investigated using a hybrid decision-making approach. To eliminate the subjectivity of decision makers and obtain reliable quantitative data, an expert group was invited for an evaluation process consisting of 5 main and 32 sub-criteria related to beach quality using pairwise comparisons and scoring. The results of the study revealed that ‘physical quality’ is the most important criterion followed by ‘ecological and economic’ criteria set. Specifically, cleanliness (9·20%), availability of a discharge node (7·30%) and security (7·22%) dominated the quality assurance policy when deciding on recreational beach locations. It is concluded that quantitative evaluation of beach quality assurance criteria can help in promotion and protection strategies in coastal landscape management.
Improvements to road surfacing practice in Ethiopia
Authors: Falconer Thomas
Published: August 2016

A study has shown that there has been a reduction in the use of thin bituminous surfacing in Ethiopia, and there is an urgent need to improve the knowledge and skills of local practitioners so that the available funds for maintaining and sealing roads can be used more effectively. Training courses were delivered by Roughton International to local industry practitioners in order to transfer knowledge of thin bituminous surfacings, which are highly cost-effective solutions for sealing lightly trafficked roads. The training courses were transferred to a local training centre and were incorporated into existing training programmes. The training participants generally gave positive feedback and felt that they learnt valuable skills. The main recommendation was that future trainees should spend significant time on project sites in order to consolidate their skills and knowledge of thin bituminous surfacings, in addition to classroom training. It was also recommended that Otta seals are explored in greater depth in Ethiopia.
Book review
Authors: Parkin John
Published: August 2016

Practical Road Safety Auditing, 3rd edn
Unsealed joints in urban concrete pavements for buses
Authors: Pradena Mauricio , Diaz Marcos
Published: August 2016

Urban pavements for buses need to resist high traffic demands without regular invasive maintenance interventions that affect the pavement clients. Although jointed plain concrete pavements can provide these requirements, sealing the joints and keeping them sealed for 10 years costs up to 45% more than unsealed joints. The objective of this paper is to evaluate the performance of unsealed transverse joints in urban pavements for buses. The field measurements made after 8 years in-service (average) in 270 unsealed joints in Chile, 150 on bus corridors and 120 on their adjacent lanes, show that only ten joints of the bus corridors were affected by very low spalling (30 mm) due to the construction process and not due to the performance of the unsealed joints. The adjacent lanes have zero joints affected by spalling. Furthermore, no pumping or measurable joint faulting was detected even after 5 million accumulated equivalent single-axle loads. These results, the 50 years of Wisconsin's experience in the USA and the deficiencies of joint seals place unsealed joints as a cost-effective alternative to optimise urban pavements for buses, considering the needs of the pavement clients – that is, users and municipal transportation agencies.
Implementing value engineering study for temporary facilities
Authors: Trigunarsyah Bambang , Hamzeh Khaled Ziad
Published: August 2016

Value engineering (VE) is a technique for reducing costs while keeping the required function, and improves performance and quality. It can be applied in many areas. In construction projects, VE is typically carried out for the project itself, but not for mobilisation and temporary facilities. For large and remote construction projects, the cost of mobilisation and temporary facilities is considerably high. So, a VE study could lead to a significant saving in the construction costs. This paper provides evidence of the significant saving that resulted by implementing VE for temporary facilities of a construction project. A case study of temporary facilities for a large power plant project is presented, and includes the VE steps and actual results. The main findings of this study suggest that the implementation of VE study for temporary facilities of construction projects could lead to a significant cost reduction, particularly in mega projects and remote projects
Transnational access to European seismic research facilities
Authors: Fardis Michael N. , Biskinis Dionysis
Published: August 2016

The experimental research in this special issue on seismic design of timber buildings has been carried out in the context of seismic engineering research infrastructures for European synergies (Series), a project funded by the European Union's (EU) seventh framework programme for research. During its 4·5 year course, Series established a seamless and sustainable platform for cooperation between Europe's research infrastructures in earthquake engineering. Series partners enhanced their potential by jointly developing novel seismic testing techniques. Moreover, they advanced their outreach to the European community of science, technology and practice in earthquake engineering by providing (free of charge) access to their experimental capabilities and research outcomes. This was, indeed, the main goal of Series: to open up select research infrastructures for transnational access (TNA) and use by European groups of researchers. Advanced experimental work was jointly conducted by 27 user groups, after peer review and evaluation of research proposals. The portfolio of infrastructures offering TNA included the unique reaction wall/pseudodynamic testing at the European Laboratory for Structural Assessment at the Joint Research Centre, the four largest shaking table facilities and the leading laboratories for centrifuge testing in Europe. After providing general information about the TNA activities within Series, the paper highlights the outcomes of selected TNA projects on buildings, including on timber buildings.
Simulating soft body impact on glass structures
Authors: Schneider Jens , Schula Sebastian
Published: August 2016

Soft body impacts are fundamental loads in safety glass design and usually govern the glass composition and glass thickness. The resistance of these glasses against soft body impact and their safety properties after fracture are generally determined experimentally by an impact test, for example as defined in the European standard EN 12600. This paper shows that the relatively complex dynamics of a soft body impact on glass plates of different types can be simulated using transient, implicit or explicit finite-element methods in very good agreement with experimentally measured data. Based on research at TU Darmstadt at the beginning of the century, the calculation methods have been available for more than 10 years, also in commercial software. This paper additionally describes and validates a quick and easy engineering verification of the numerical simulations by means of a simplified analysis using equivalent static loads derived from a two-degrees-of-freedom (2-DOF) model. Both methods are now part of the design method included in the new version of the German standard DIN 18008-4 ‘Glass in building – design and construction rules – part 4: additional requirements for barrier glazing’.
Studies on determining the bending strength of thin glass
Authors: Maniatis Iris , Nehring Gordon , Siebert Geralt
Published: August 2016

In architecture, the term ‘thin glass’ is normally used for glass less than 3 mm thick. The present study aimed to address the lack of reported research concerning appropriate testing configurations and derivation of analytical equations for calculating the bending strength of thin glass to enable its use in architectural applications. Two testing methods (a modified four-point bending test and a buckling test) for determining the bending strength of thin glass are presented, supplemented with analytical approaches for calculating the relative tensile bending stresses. These methods take the geometrical non-linearity into consideration. Experimental and numerical investigations showed that both methods are suitable and satisfactorily represent the tensile bending stress in the centre of the specimen. It is, however, believed that the modified four-point bending test is preferable since the test equipment according to EN 1288-3 can be used. Use of this equipment is widespread and the test setup and execution are simple. To identify influencing and limiting parameters on the bending strength, a numerical sensitivity analysis was performed. This showed that small variations of the parameters glass thickness, Young's modulus or Poisson's ratio have an influence on the value of the tensile bending stress.
Shaking table tests on a three-storey timber building
Authors: Tomasi Roberto , Casagrande Daniele , Grossi Paolo , Sartori Tiziano
Published: August 2016

This paper reports on a shaking table test conducted on a timber-framed building sheathed with oriented strand board within the framework of the European Series project at the National Laboratory of Civil Engineering in Lisbon, Portugal. The test structure was a full-scale, three-storey, 7 m × 5 m plan building. The aim of the tests was to assess the integrity of the structural members and the non-structural components during a seismic event. The structural design was carried out in accordance with European standards. The input signals comprised ‘accelerograms’, which were scaled versions of those recorded during the Montenegro (1979) and Tohoku (2011) earthquakes. The outcome of the tests showed excellent seismic behaviour, as demonstrated by the fact that the structure frequency did not change until the last step of the procedure. Moreover, after 17 simulations, no visible damage was detected.
A frictional damping based design methodology for structures
Authors: Rahmani-Samani Hamid , Mirtaheri Masoud , Hariri-Ardebili Mohammad Amin
Published: August 2016

An improved direct displacement design procedure is proposed for frictional damping based structural systems. The system is composed of beams and columns which are connected by simple connections and bracing members equipped with frictional dampers. It is shown that under the seismic loading no material yielding occurs in the structure, no component replacement is needed and the repair operation only involves re-centering of the dampers. Using the proposed design procedure, the slippage loads of the dampers are chosen such that the target displacement is satisfied. This method is used to design several structures with different heights. Non-linear transient analysis is performed to evaluate the applicability of the proposed methodology. Results show that all the case studies satisfy the intended performance objectives.
Seismic damage detection for a steel braced frame structure
Authors: McCrum Daniel P. , Staino Andrea
Published: August 2016

A new approach for global detection of seismic damage in a single-storey steel concentrically braced frame (CBF) structure is presented. The filtered lateral in-plane acceleration response of the CBF structure is integrated twice to provide the lateral in-plane displacement that is used to infer buckling and yielding damage. The level of interstorey drift of the CBF during a seismic excitation allows the yield and buckling of the bracing members to be identified and indirectly detects damage based on exceedance of calculated lateral in-plane displacement limits. A band-pass filter removes noise from the acceleration signal followed by baseline correction being used to reduce the drift in velocity and displacement during numerical integration. This pre-processing results in reliable numerical integration of the frame acceleration that predicts the displacement response accurately when compared to the measured lateral displacement of the CBF structure. Importantly, the structural damage is not assumed through removal of bracing members, rather damage is induced through actual seismic loading. The buckling and yielding displacement threshold limits used to identify damage are demonstrated to identify accurately the initiation of buckling and yielding.
Smart glazed cable facade subjected to a blast loading
Authors: dos Santos Filipe Amarante , Cismasiu Corneliu , Bedon Chiara
Published: August 2016

This paper investigates the dynamic behaviour of cable-supported glazing facades subjected to medium-level air blast loads. Preliminary numerical studies are carried-out in SAP2000 by means of a geometrically refined and simplified lumped-mass finite-element numerical model, in order to assess the major effects of the design blast load in the main facade components. As shown, both the glass panels and the cable system are able to properly accommodate the incoming impulsive loads, typically involving extreme deflections and high tensile stresses. In order to mitigate the effects of blast pressures on the glazing system, an innovative and particularly efficient active control system is proposed. The control system implemented in the glazed cable facade is based on a proportional-integral-derivative (PID) control algorithm, in which the control variable is the tension in the cables.
Effect of reduced concrete cover on strength of lapped joints
Authors: Cairns John , Goodchild Charles
Published: August 2016

The paper reports on an experimental investigation into the performance of lapped joints in structural concrete. The investigation focuses primarily on concrete covers close to or below the minimum set for structural reasons in design codes such as Eurocode 2 or ACI 318. Two other parameters are also varied in the tests reported here, namely the proportion of bars lapped at a section and the relative size of the bars within a lapped pair. It is found that a reduction in minimum cover from 1·2 to 0·6 times bar diameter would require an increase in lap length of 21% to develop the same stress in a lapped bar. It is verified that provisions for lapped joints in the fib Model Code 2010 are valid for minimum covers down to 0·5 times the diameter of a lapped bar. It is also found that lap strength does not change significantly when laps are staggered. The finding raises questions over the validity of the α6 coefficient in Eurocode 2, which is dependent on the proportion of bars lapped at a section. Results demonstrate that, where lapped bars differ in diameter, lap length may safely be based on the diameter and covers to the smaller diameter bar.
Analysis of the seismic performance of a two-storey log house
Authors: Branco Jorge M. , Lourenço Paulo B. , Aranha Chrysl A.
Published: August 2016

The dearth of knowledge on the load resistance mechanisms of log houses and the need to develop numerical models that are capable of simulating the actual behaviour of these structures has pushed efforts to research the relatively unexplored aspects of log house construction. The aim of the research that is presented in this paper is to build a working model of a log house that will contribute towards understanding the behaviour of these structures under seismic loading. The paper presents the results of a series of shaking table tests conducted on a log house, and goes on to develop a numerical model of the tested house. The finite-element model has been created in SAP2000 and validated against the experimental results. The modelling assumptions and the difficulties involved in the process are described, and, finally, a discussion on the effects of the variation of different physical and material parameters on the results yielded by the model is provided.
Brittle failure in timber connections loaded parallel to the grain
Authors: Jensen Jørgen L. , Girhammar Ulf Arne , Quenneville Pierre
Published: August 2016

An existing beam-on-elastic-foundation (BEF) model was used to determine the perpendicular-to-grain tensile stresses in timber members subjected to loading parallel to the grain by bolted connections. A set of relatively simple equations for the analysis of a Timoshenko beam of finite length on a Winkler foundation is given, and appropriate foundation stiffness values are discussed. While previous applications of the model have associated the foundation stiffness with the perpendicular-to-grain elastic strain in the timber, it is suggested that a fracture layer be introduced and the foundation stiffness be associated with the perpendicular-to-grain tensile strength and the mode I fracture energy of the wood. The latter estimation of the foundation stiffness, which leads to a so-called ‘quasi-non-linear fracture mechanics model’, has been applied with success to other problems where the BEF model has been used for the analysis of mode I fracture. An existing model for the analysis of the pure mode II fracture, which is also a quasi-non-linear fracture mechanics model based on similar assumptions as the proposed model for analysis of the mode I fracture, is reviewed. A simple way of handling mixed-mode fracture problems by means of the simple empirical interaction of the proposed pure mode I and pure mode II quasi-non-linear fracture mechanics models is discussed.
Energy absorption of steel hollow tubes under bending
Authors: Maduliat Soheila , Ngo Tuan Duc , Tran Phuong
Published: August 2016

This work describes an analytical study on steel circular hollow sections under pure bending moment in order to understand its collapse deformation and to predict the energy absorption mechanism. Different from experimental and numerical analyses, which require extensive resources, the yield line mechanism (YLM) analytical model utilised in this work could provide various useful insights such as the collapse response of steel hollow sections when failure is formed at localised plastic hinge points. This is when a section fails and the YLM of failure forms at its localised plastic hinge point. Initiating a geometrical model and determining the energy absorption by different hinge lines is a complex exercise. Therefore, a simplified equation to estimate the failure curve of steel hollow sections is proposed. After examining the collapse response of the steel hollow sections using a simplified YLM method, the energy absorption capacity of these sections is investigated by performing excessive parametric study and correlation. By using this simplified method, the energy absorption due to failure is investigated. It is concluded that, for sections with the same cross-section, the section with the lower slenderness ratio has a higher energy absorption capacity and is more desirable to use as an energy absorber in industry.
Experimental and numerical investigation of a large tuned liquid column damper
Authors: Cammelli Stefano , Li Yin Fai
Published: August 2016

During the early design stages of a relatively slender 63-storey high-end residential tower located on the East Coast of the USA, a series of high-frequency force balance and simultaneous pressure integration wind tunnel studies highlighted that the highest occupied levels of the tall building could experience wind-induced motion that had the potential to exceed standard industry occupant-comfort criteria. In order to mitigate these excessive vibrations, additional damping was needed. Among the different types of auxiliary damping devices that can be introduced in a tall building to control wind-induced sway, the so-called tuned liquid column damper was chosen for this specific project primarily because of its simplicity in construction, low initial cost and nearly maintenance-free operation.
Vibrations of metal web joist timber floors with strongbacks
Authors: Zhang Binsheng , Kermani Abdy , Fillingham Tony
Published: August 2016

The aim of this research is to assess the effects of joist spacing, strongbacks and ceiling on the dynamic response of timber floors with metal web joists so as to evaluate the vibrational design criteria, for example, modal frequencies, modal shapes, damping and unit point load deflection, required by Eurocode 5-1-1 and the UK National Annex for timber floors. In general, joist spacing, strongbacks and ceiling do not greatly influence the fundamental frequency and damping ratio, but affect higher modal frequencies. The measured damping ratio for the fundamental mode is 0·86% on average. The use of strongbacks considerably reduces the number of first-order modes below 40 Hz, and provides easier fulfilment of the velocity design criterion. The test results indicate that the decrease in joist spacing, the increase in number, size and stiffness of strongbacks, and the use of a ceiling all greatly reduce the maximum displacement of the floors. On average, the calculated displacements based on the equations in the UK National Annex are close to those measured.
Load-carrying capacity test of a long-span timber truss
Authors: Branco Jorge M. , Varum Humberto , Ramisote Vitor , Costa Aníbal
Published: August 2016

The aim of this work was to study the behaviour of existing timber trusses in order to improve the knowledge that may support engineers in the definition of more adequate restoration interventions in old buildings, particularly of long-span timber structures, as industrial or monumental constructions. For this purpose, a cyclic load-carrying test was carried out on a full-scale timber planar truss rescued from an old industrial roof structure. Before the tests, an accurate geometrical characterisation was performed and the biological condition of the timber elements was evaluated by non-destructive tests to determine their effective cross-section. The results of the destructive load-carrying test were used to calibrate a numerical model with the aim of assessing the effect of the effective cross-sections of the truss components and the axial stiffness of the joints on the overall response observed during loading. The full-scale test performed proved the importance of this type of testing in assessing the behaviour of existing timber trusses. It is essential to assess the damage of the joints and to model correctly their behaviour so as to numerically reproduce the overall behaviour of timber trusses.
Parametric study of RC beams under a wide range of loading rates
Authors: Adhikary Satadru Das , Li Bing , Fujikake Kazunori
Published: August 2016

Over the years, numerical investigation has been presented as a viable alternative to experimental studies, as testing of structural members to assess the effect of several parameters at a time is not only cumbersome but also expensive. Thus, after validating the results from a finite-element analysis with experimental outcomes, a numerical parametric study was conducted to investigate the effects of various parameters on the dynamic increase factor (DIF) of the maximum resistance and the failure mode of reinforced-concrete beams under a wide range of loading rates. From the results, it can be concluded that the DIF of maximum resistance for beams with a small amount of longitudinal reinforcement is greater than that for beams with a large amount of longitudinal reinforcement. A change in the failure mode can be observed (mainly at high rates, 2 m/s) when the longitudinal reinforcement ratio is increased (approaching the balanced-reinforcement ratio) in an under-reinforced beam. For beams with a large amount of transverse reinforcement, the DIF would be lower than for beam with a small amount of transverse reinforcement. Furthermore, it was found that the yield strength of longitudinal reinforcement is the key parameter affecting the failure mode change from flexure at static loading to shear at high loading rates.
Load transfer and arching analysis in reinforced embankment
Authors: Fattah Mohammed Y. , Mohammed Hadeel A. , Hassan Hanan A.
Published: August 2016

In a previous study, a series of 9 model tests performed on embankment models resting on soft clay treated with and without ordinary stone columns (OSC), encased stone columns (ESC), and with horizontal layer of geogrid at interface and at 0·1 h height has been carried out to investigate the behaviour of piled (stone columned) and geogrid reinforced embankments. In this paper, these tests are simulated numerically by the finite element method using the program Geostudio (SIGMA/W). Firstly, reanalysis was done of experimental work of embankment models constructed on soft clay treated with OSC and ESC. Secondly, embankment models reinforced by a horizontal layer resting on soft clay strengthened with OSC and ESC were analyzed. A horizontal layer of geogrid is embedded at different levels of embankment height. It was concluded that in the embankment models constructed on soft clay treated with stone columns at a spacing s = 2·5 d with length to diameter ratio L/d ratio = 8, the maximum bearing improvement ratio (qt/qunt) equals 1·33 for the ordinary stone columns and 1·59 for the encased stone columns and about 1·13 and 1·23 when one layer of geogrid is embedded at interface or at 0·1 h height, respectively.