bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of Semi-Markov Decision Process in Bridge Management
Authors: Hajdin Rade , Mašović Snežana , Stošić Saša
Published: March 2016

The state-of-the-art Bridge Management Systems (BMSs) feature tightly coupled deterioration and preservation optimization model that enable determining the most cost-effective maintenance strategies at both the project and network levels. In other to improve deterioration model, many authors suggest the application of Weibull distribution for the sojourn time in condition states. Consequently, one has to solve semi-Markov decision process to determine the optimum preservation policy. It can be shown that the long-run optimal policies obtained using semi- Markov model doesn’t differ from those of time homogenous Markov chains for average cost criteria if the expected sojourn times in each condition state are same for both model. However, financial needs differ between the models depending on distribution parameters of sojourn time in each condition state. It is therefore that the estimation of these parameters is crucial for the realistic estimation of the financial needs. In this paper, the semi-Markov decision process is briefly presented and recommendations regarding its practical applications in bridge management are given.
Multi-criteria optimization framework for road infrastructures under different scenario of climate change
Authors: Orcesi Andre , Chemineau Helene , Van Gelder Pieter , Van Erp Noel , Lin Pei-Hui , Obel Nielsen Kim , Pedersen Claus
Published: March 2016

This paper presents an optimization framework for critical road infrastructure elements that integrates economic aspects. This optimization framework is used to determine optimal management strategies of infrastructures under scenarios of climate change and financial constraints. Optimal management strategies, based on the consequences of possible actions on the future condition of the system, are determined through an optimization process under uncertainty. The aim is to maximize the performance level of structures. Such an optimization procedure is a first step in the development of asset management tools that allow national road administrations to assess the necessary additional effort to satisfy performance constraints under different scenario of climate change. The integration of such concepts in the decision process by national roads administrations represents a step forward in management strategies.
Structural reliability of existing city bridges
Authors: Hellebrandt Laura , Steenbergen Raphaël , Blom Kees , Vrouwenvelder Ton
Published: March 2016

Full probabilistic reliability analysis may be valuable for assessing existing structures. Measures for increasing the safety level are quite costly for existing structures and may be unnecessary when such a decision is grounded on a conservative analysis for determining the structural reliability. This may be avoided by applying a more detailed analysis as well as considering local traffic loading conditions rather than general load models. In this paper we present the structural reliability analysis of a small span inner city concrete bridge beam using Monte Carlo simulation. The resistance is based on results from an optimal design according to a given code. The load is represented by the extreme value distribution of the load-effect, resulting from a probabilistic traffic load model based on Weigh-In-Motion (WIM) measurements. Using commercial software typically available to engineers, the reliability is calculated and compared to the required minimum reliability level.
Nonlinear structural analysis as an assessment tool for existing concrete structures
Authors: Boer Ane , Hendriks Max A. N. , Veen Cor , Belletti Beatrice
Published: March 2016

This paper gives an overview what the impact of nonlinear analysis can have on the remaining capacity of an existing concrete structure. Today and in the past a concrete structure is designed on the level of a linear analysis. The layout of the reinforcement is mostly designed on a cross sectional base, where quasi nonlinear behaviour on the cross-section is included. Also in the past some phenomena, like shear force behaviour, were neglected in design recommendations. The shift to a full nonlinear analysis is a great step, so after more than 20 years of improvement of concrete material models and improvement of CPU, in 2007 a decision has been made to setup a workshop around shear force behaviour related to nonlinear analysis. The result of this workshop was to setup a Nonlinear guideline for concrete structures for the framework of the re- examination of existing concrete structures. In 2010 the Model Code 2010 was published with safety formats to extend the checks of concrete structures, re-examinated by nonlinear analysis. The first draft of Nonlinear guideline was published in 2012, reason to setup a second workshop to get a better dissemination under the concrete analysis.
Performance of a prestressed concrete bridge loaded to failure
Authors: Bagge Niklas , Nilimaa Jonny , Blanksvärd Thomas , Bernspång Lars , Täljsten Björn , Elfgren Lennart , Sas Gabriel , Tu Yongming , Carolin Anders
Published: March 2016

Methods for assessment and strengthening of existing bridges need to be tested and calibrated. To do this, a full-scale loading to failure was carried out in 2014 on a 55 year-old post-tensioned five span girder bridge in Kiruna, Sweden, with a total length of 121.5 m. The tests focussed on: (a) failure of the main girders, (b) failure of the slab, (c) condition of post-tensioned tendons, and (d) the performance of two carbon fibre reinforced polymer (CFRP) strengthening systems. The following are the results:

The main girders failed after extensive yielding of the reinforcement in a combined bending- shear failure. Preliminary comparisons with existing codes indicate a high safety. Preliminary comparisons with finite element assessment methods give good correspondence.

The slab failed suddenly due to punching shear. Preliminary comparisons with codes indicate a very high safety.

The post-tension tendons generally were in a good condition.

The first strengthening system consisting of prestressed laminates of CFRP was applied to one of the outer main girders. The system failed due to debonding of the CFRP at about ¾ of the ultimate load. The second system consisted of near surface mounted CFRP rods applied to the mid main girder. It showed no signs of slip in the anchorage zones and the CFRP sustained maximum strains of about 1.2 % without fibre rupture.
Remaining Fatigue Life Estimation of Railway Bridge Members Subjected to Time-dependent Corrosion
Authors: Adasooriya Nirosha , Siriwardane Sudath C.
Published: March 2016

Remaining fatigue life estimation of corroded members of a railway bridge is presented in this paper. The method used in this study addresses effects of material loss due to general (uniform) corrosion and fatigue strength degradation of material due to corrosive environment. Initially the information of the considered bridge is discussed. The inspection records, corrosion information and loads on the bridge are discussed in detail. Then a model is introduced to describe time-dependent growth of general corrosion wastage. Then finite element method employed time history dynamic analysis is performed to obtain stress histories of corroded members. A full range S-N curve is proposed for corroded structural detail. The sequential law, which takes the loading sequence effect more precisely in to account than Miner’s rule, is used to obtain remaining fatigue lives. Finally significance and validity of the method are confirmed by comparing the predicted fatigue lives with previous estimations.
Monitoring shear-induced degradation of reinforced and pre- tensioned concrete members
Authors: Stoerzel Joerg , Randl Norbert , Strauss Alfred
Published: March 2016

In the frame of a research project funded by the Austrian Research Foundation (FFG) 2 series of 4 pre-tensioned and non prestressed beams with rectangular and T-shaped cross-sections have been produced in order to investigate the behaviour under shear loading and also the effect of the prestress on load bearing capacity and on ductility. In order to investigate the interaction between shear force, bending moment und normal force the pre-tensioning was varied between 100% and 50%. Special focus was laid on the crack development and SLS criteria as well as the ductility after reaching ultimate load level. During the first test series different conventional measuring methods were used to monitor the external and internal deformations caused by shear loading, in order to evaluate the sensitivity and correlation of the different measurements. As a result of the first test series, the monitoring layout and the performed numerical analyses were optimized and modern measurement methods in terms of DIC step wisely integrated into the further test series. Finally, the suitability of the different applied measuring techniques for recording shear behaviour and the potential to optimize the monitoring of shear degradation was evaluated.
Shear failure of pre-stressed concrete T-shaped girders: Experiment and nonlinear modeling
Authors: Slowik Ondřej , Novák Drahomír , Krug Bernhard , Strauss Alfred
Published: March 2016

The paper presents essential steps in the development of numerical computational model of destructive test of prestressed T-shaped concrete girder. First, a series of material, small scale component tests have been performed in collaboration between two laboratories. Based on these tests identification of fracture-mechanical parameters (and their statistics) for two concrete mixtures used for the production of precast structural members was performed. Subsequently, studies have been performed on (a) full scale pre-stressed concrete roof elements with a span width of 30.00 m and a height of 0.50 m to 0.90 m, made of C50/60 and different reinforcement layouts, and (b) twelve scaled laboratory tested elements with a length of 5.00 m and heights from 0.30, 0.45 and 0.60 m in order to capture size effects in the shear bearing performance.
UHPFRC Strengthening Method for Existing Bridges
Authors: Duan Lan , Houankpo Tchehoungbo Olivier Noukpo , Dong Peng , Wang Chun-Sheng , Brühwiler Eugen
Published: March 2016

Ultra-high performance fiber reinforced concrete (UHPFRC) is an optimal selection for bridge strengthening projects, because of the distinguished material properties like high compressive and tensile strengths, ductility, durability, compactness, and low creep. This paper focuses on a strengthening method for both steel bridges and concrete bridges using UHPFRC. For steel bridges, UHPFRC overlay is proposed to strengthen orthotropic steel bridge decks. The UHPFRC layer acts in composite action with the steel deck plate by applying an epoxy resin glue at the interface of the two materials, which is verified to be an effective way to improve structural rigidity by means of experiments. For concrete bridges, UHPFRC layer is cast on the top surface of the deck slab. This technology has already been applied to several bridges as waterproofing layer and to effectively increase the ultimate resistance of the deck slab of bridges. Besides, for the bottom flange of concrete girders in the tensile state, UHPFRC and steel composite strengthening method is proposed. Studs are anchored in the bottom flange of the original concrete girder and a U- shaped steel plate with studs is arranged such as to cover the bottom flange and part of the web. This U- shaped steel plate also serves as a formwork for UHPFRC casting between original concrete girder and steel plate, such that an overall cross section is formed and the UHPFRC-steel plate strengthening part work in composite action with the original girder. A concrete bridge box girder section is selected as a case study to validate the UHPFRC strengthening method for both steel and concrete bridges with the objective to improve structural performance effectively.
Challenges in the Evaluation of Existing Concrete Structures: Margaret Avenue Bridge
Authors: Habel Katrin , Beard Laaber Christine , Allen Steve
Published: March 2016

The De la Concorde Overpass in Laval, Quebec, Canada failed in 2006 and cost the lives of five people. The failure initiated in the half-joint of the thick cantilever slab that supported the drop-in span. Following this failure, a number of owners across Canada evaluated non-redundant half-joint connections of concrete bridges, including the Margaret Avenue Bridge in Kitchener, Ontario, Canada. This paper describes the evaluation of the half-joint detail of the structure including review of existing information and a discussion of uncertainties that led to the closure and demolition of the structure. The paper critically compares observations during the demolition of the structure with the assumptions made during the evaluation. The findings during demolition confirmed the majority of the assumptions and validated the decision to demolish the structure.
Strengthening of existing RC frame in case of construction of additional floor, with account for the construction stages
Authors: Traykova Marina , Boiadjieva-Marinova Raina , Traykov Alexander
Published: March 2016

An additional floor is designed on the top of an existing RC building with frame structure. New transfer columns are supported on the existing beams of the top level. The frame is recalculated and design checks are carried out taking into account the construction stages. The corresponding conclusions about the redistribution of the internal forces depending on the type and the age of the structure are drawn. The necessary strengthening of the existing structure is considered, based on the results obtained by the calculations. Strengthening with FRP and RC jackets of the structural elements is considered as a final solution.
Extend the life of existing railway bridges – Results from EU FP7 project MAINLINE
Authors: Nilimaa Jonny , Häggström Jens , Blanksvärd Thomas , Täljsten Björn , Elfgren Lennart , Tu Yongming , Carolin Anders , Paulsson Björn
Published: March 2016

There is a need to extend the life and capacity of many existing bridges. One of the objects of the EU FP7 Project MAINLINE, 2011-2014, was to facilitate this. Guidelines for assessment and strengthening methods are presented as well as case studies in which existing bridges are studied in order to extend their life length.

One example is the prestressing of the slab in a one-span concrete trough bridge in order to increase its load-carrying capacity. Horizontal holes were drilled trough the slab and in them steel bars were placed and post-tensioned. In this way a compressive stress was introduced into the concrete section so that it’s bending and shear capacity was increased.

In another study a metal truss bridge was monitored in order to check strain and stress ranges in critical connections to enable an enhanced evaluation of the remaining fatigue resistance. The studied bridge was then replaced and loaded to failure to study its robustness and the reliability of applied assessment methods. The results could then be applied to prolong the life of an identical twin bridge located in the northern part of Sweden.

A Life Cycle Assessment Tool (LCAT) has been developed to enable Infrastructure Managers to choose optimal maintenance strategies.
Cold Retrofit Method Study for Fatigue Cracking of Steel Bridge
Authors: Wang Chun-Sheng , Ou Chang-Yang , Zhai Mu-Sai , Duan Lan
Published: March 2016

Lots of steel bridges have endured performance challenge from fatigue cracking problem. Therefore, research on retrofit methods for fatigue cracking in steel bridge is very important. To avoid introducing new fatigue details during retrofit process, cold retrofit study is encouraged and focused in this paper by two experimental studies. The first is cold retrofit for orthotropic steel bridge deck. Fatigue test of a full-scale orthotropic steel bridge deck was conducted and different retrofit methods were applied to the fatigue damaged deck, including drilling stop holes and bonding steel plate. Test result shows bonding steel plate is an effective retrofit method. The second is cold retrofit for steel girder with gusset plates for lateral braces, since out-of-plane distortion often happens in the web gaps between the flange plates and vertical stiffeners, which leads to initiation and propagation of fatigue cracks. Fatigue test was carried out to study the fatigue mechanism and to verify the effectiveness of cold retrofit method, as well as the fatigue performance of post-retrofitted details. Different retrofit methods were experimentally studied, including drilling stop holes, bonding or bolting angle steel. The study result shows cold retrofit method can retard distortion-induced fatigue cracks. Based on the experimental study above, bonding angle steel method was applied to orthotropic steel deck of a long span cable-stayed bridge.
Extending our Nocioceptive Sense to Structures: Haptic Interfaces for Structural Health Monitoring
Authors: Mascareñas David , Farrar Charles
Published: March 2016

The ultimate goal of the structural health monitoring (SHM) field is to endow structures with a nervous system not unlike those found in biological organisms. We started asking the question, could a more kinesthetic strategy help us address challenges the structural health monitoring community was facing with respect to detecting and characterizing damage? Could we use haptic interfaces to endow humans with a nocioceptive sense for a structure? At least four different studies involving various haptic interfaces for structural health monitoring have been executed. In this presentation we will review the principles of the haptic SHM paradigm, we will provide a summary of the results completed to date, the particular applications the paradigm seems suited to, and we will discuss the research problems that need to be addressed to advance this paradigm.
Unmanned Aerial Systems (UAS) – Survey and monitoring based on high-quality airborne photos
Authors: Hallermann Norman , Morgenthal Guido , Rodehorst Volker
Published: March 2016

Monitoring strategies play a major role for achieving the target service life of existing structures. Conventional inspections are based on visual investigations. The data acquisition process is the most time consuming, personal as well as technical complexity and thereby a cost intensive part of inspections. This paper discusses a novel method, respectively a workflow of visual inspection including a highly-accurate survey of structures based on aerial photos taken by remote controlled professional unmanned aerial systems (UAS). This approach could provide an important contribution to monitoring strategies in terms of quality, safety and efficiency. The paper shows two case studies of UAS in condition monitoring based on the combination of conventional inspection measurements with modern photogrammetric computer vision methods for geo- referenced 3D-modelling of structures and automatic post-flight damage detection.
Continuous dynamic monitoring of lively footbridges
Authors: Cunha Álvaro , Caetano Elsa , Moutinho Carlos , Hu Wei-Hua , Cardoso António
Published: March 2016

This paper presents three different case studies of continuous dynamic monitoring of lively footbridges, aiming at the verification of vibration serviceability limits defined by recent footbridge guidelines for vertical and lateral human induced vibrations, as well as the demonstration of the feasibility of vibration based damage detection, taking into account the experience gained at the Laboratory of Vibrations and Structural Monitoring (ViBest, www.fe.up.pt/vibest) of FEUP with the development of different research and consultancy works.
Traffic characteristics and load responses of specific bridge based on the measured WIM data
Authors: Wang Xuejing , Ruan Xin
Published: March 2016

This paper gathers 190 days traffic data measured by the WIM (weigh in motion) system on Jiashao Bridge, and analyse the characteristics of vehicle and vehicle weight in lateral lanes. Loading responses of several featured structural effects which are important for condition evaluation of Jiashao Bridge are studied under actual traffic condition. The response values are then compared with those calculated from the standard traffic load model in D60. Results show that the characteristics of transverse distribution of traffic flow is significant. Light vehicles tend to choose the inside lanes, while multi-axis vehicles barely choose passing lane. Loading responses present significant differences on lateral lanes. Lane 1 gets the largest loading response and the responses of the rest inner two-lanes are similar. All the loading responses of overall lanes are under 50% of the values calculated by design codes. In conclusion, the safety and usability of the structure can meet the requirements in the current traffic flow, and the design and evaluation models for different lanes should be analyzed differently.
Documentation of Bridges by Terrestrial Laser Scanner
Authors: Truonghong Linh , Laefer Debra F.
Published: March 2016

Bridge structures are subjected to deterioration due to excessive usage, overloading, and aging material. For the last two decades, a significant amount research has been developed for collecting data for structural health monitoring. Yet, visual investigation with an on-site inspector remains the predominant method. This is true despite the highly subjective and time consuming aspects of this approach. Alternatively, terrestrial laser scanning can acquire surface details of structures quickly and accurately and is, thus, an emerging means to overcome the shortcomings of direct visual inspection. This paper presents a procedure for data collection for bridge inspection documentation and proposes a “cell-based method” for determination of structure deterioration (involving vertical deformation and lateral distortion), as well as surface loss due to corrosion. The Guinness Bridge built in 1880s located in Dublin council, Ireland is selected as a case study to illustrate the efficacy of the proposed method.
The Constructions Vibration Control by Tuned Mass Dumper
Authors: Longarini Nicola , Zucca Marco , Silvestro Giuseppe
Published: March 2016

In this paper the Vibration Control by the Tuned Mass Dumper (TMD), in important and symbolic constructions, are illustrated. Some TMD optimization procedures are discussed for different types of constructions (new tall buildings, an existing masonry chimney and a new footbridge) for the seismic and wind actions. By the TMDs, the structural behaviors improvements are shown, either for the Ultimate Limit State (ULS), either for the Serviceability Limit State (SLS). To appreciate the structural improvements by TMD installation, for each types of constructions, structural analysis by finite elements model (FEM) are carried out with and without TMD. Finally, for each TMDs, a design hypothesis are showed pointing out the installation procedures and the related costs.
Damping of Stay Cables by Semi-Active Friction Dampers
Authors: Wagner Mia , Svendsen Martin Nymann , Høgsberg Jan
Published: March 2016

This paper concerns experimental investigations of passive and semi-active friction dampers for stay cables. Different control strategies have been tested and the damper performances have been compared. The present experimental results with the semi-active device show that it is possible to outperform the passive damping by a factor of 1.8 on the obtained damping ratio with the same maximum damper force. This has been achieved by using two key concepts in the control strategy for the semi-active damper. The first concept is real-time adaption of the damper force to the corresponding vibration amplitude of the cable and the second concept is realization of apparent negative stiffness by real-time on-off control of the friction damper brakes.
Volgograd-Bridge: Efficiency of passive and adaptive Tuned Mass Dampers
Authors: Benicke Oliver , Butz Christiane
Published: March 2016

In Volgograd the inauguration of the new road bridge across the river Volga took place in October 2009. In May 2010 the bridge was temporarily closed for traffic because of excessive wind-induced vertical vibrations of appr. ± 400 mm amplitude. The owner decided to retrofit the bridge with an adaptive tuned mass damper system.

The paper shows a more precise approach to determine effective structural damping based on harmonic analyses using a FE model of the bridge. It is used to determine effective structural damping for the structure without and with passive and adaptive TMDs. While it is shown that passive TMDs are not able to fulfil serviceability requirements, the adaptive TMD system is proven to provide sufficiently damping to prevent excessive vibrations.
A New Solution for Fabrication & Erection of Composite Box Girder of Cable-Stayed Bridge
Authors: Zhang Hong , You Xinpeng , Zhang Yongtao
Published: March 2016

Quanzhou bay bridge is a sea-crossing approach which is located on the southeast coast of China near Quanzhou city. The main bridge is a cable-stayed bridge with steel-RC composite box girder and main span 400m. Unlike the traditional wet joints between RC decks of composite segments, a new solution with dry joints for fabrication and erection of composite girder segments was used in Quanzhou bay bridge. The steel box girder segments and RC decks were fabricated separately at first. The composite segments were assembled and the steel part and RC part were combined. Because of the dry joints, the composite segments must match with each other. The fabrication and assembling works are all done in the factory. Then the integral composite segments were transported to the bridge site and erected by deck crane. Segments were connected by temporary prestressed steel bars after the deck joints were daubed with epoxy glue. The joints at steel part of composite girder were welded finally. The new solution can omit concrete pouring and casting at the construction site and improve the efficiency and quality of composite segments erection. The impact on environment during construction procedure is also reduced.
CNC-fabricated formwork for a UHPFRC thin folded plate arch
Authors: Mayencourt Paul , Robeller Christopher , Weinand Yves , Loraux Christophe , Brühwiler Eugen
Published: March 2016

Folded plate structures or shells are statically efficient structures. However, their construction is limited by the complexity and cost of their formwork. We used Computer Numerical Control Milling Technology to design a wooden formwork for an Ultra-High Performance Fibre Reinforced cement-based Composite (UHPFRC) folded plate arch. This paper describes the design and assembly of a formwork made from cross-laminated veneer lumber panels (LVL) with integrated wood-wood connections and the testing of the resulting thin origami-like UHPFRC arch. Currently achieved for a lab scale, CNC wood milling technology combined with integrated panel joints could enable mass-customized formwork for complex structures. UHPFRC is probably the only existing material with required strength and sustainability properties for ultra-thin structures. However, special attention should be given to the casting direction and fibres orientation in sharp edges. Based on this consideration and the result of the first lab test, some geometric adjustments and construction details are proposed and discussed in this paper.
Structural behaviour of Ultra-High Performance Fibre Reinforced Concrete Columns subjected to eccentric loading
Authors: Singh Manpreet , Ali M. S. Mohamed , Sheikh A. H.
Published: March 2016

An experimental investigation conducted on ultra-high performance fibre reinforced concrete (UHPFRC) columns is presented in this paper. The columns consisted of longitudinal and transverse reinforcement, tested under concentric and eccentric compressive loads with varying load eccentricities. The UHPFRC manufactured with locally available raw materials attained compressive strengths of 140 to 160MPa. The experimental data of axial load with lateral and axial deformations, mode of failure was obtained for each test. The cover spalling was not observed for all the columns. The interaction diagram of axial load-bending moment is established for compression members and is in good agreement with the test results.
Bridge over the motorway A27, steel truss with a FRP deck
Authors: Steenbrink Arjen , Kaptein Gijs
Published: March 2016

In the Netherlands a bridge is built crossing the motorway A27 near Utrecht. This bridge was constructed as a combination of steel and FRP, with a total length of 140 meters. The bridge is made of a steel truss girder and a deck of FRP (composite).The connection of the composite deck to the steel truss girder was a challenging part. To solve this problem two load-paths are introduced. The first is made with an adhesive compound, the second with a pin-hole connection. Also the location of the bridge with the foundation inside a polder construction with highly compressible soil was a challenge to solve. The use of a jet grouting was necessary to solve this problem.
Evaluation of Bolted Single Support Bar Modular Bridge Joint Systems for Infinite Fatigue Life under Simulated Vehicular Loading
Authors: Artmont Frank A. , Roy Sougata
Published: March 2016

Infinite life fatigue resistance of bolted single support bar modular bridge joint systems (MBJS) was recently evaluated by testing full-scale MBJS subassemblies at the ATLSS Engineering Research Centre of Lehigh University. The test results demonstrated that with adequate bolt pretension, the infinite life fatigue resistance of CB-SB connections in SSB MBJS can be classified as AASHTO Category B. The current AASHTO Specifications classify this detail as Category D. Based on analytical and experimental studies, revisions to the existing AASHTO Specifications for MBJS were proposed.
Earthquake-induced Collapse Simulation of a Super Long Span Cable- Stayed Bridge Based on an Open Source FE Program
Authors: Kaiqi Lin , Linlin Xie , Xinzheng Lu , Lieping Ye
Published: March 2016

Currently, the seismic performance assessments of long span bridges are generally conducted using commercial finite element (FE) software packages, which to some extent limit the in-depth investigation of associated topics. A numerical model system is proposed to simulate a super long span cable-stayed bridge with a maximum span of 1500 m based on an open source FE software package (i.e., OpenSees). The seismic performance of this bridge is investigated. The simulation results of OpenSees and the commercial software MSC.Marc are compared with a good agreement. Furthermore, a collapse simulation of the bridge is also successfully performed and the corresponding collapse mechanism is revealed. The research outcome could provide a reference for further studies on the seismic performance of super long span cable-stayed bridges based on open source FE programs.
Effect of a Base Isolation System for Reduction of Annual Seismic Risk of a Steel Building
Authors: Daneshi Mehdi , Kalantari Afshin
Published: March 2016

This research focuses on the effects of base isolation on annual probable seismic loss in a typical existing educational building. The physical seismic damage is related to economic losses to investigate the financial aspects of application of base isolation system in building. Meanwhile the probabilistic nature of both seismic event and structural response has been considered by the employed methodology. The building, which experienced the 2012 East Azerbaijan –North West of Iran- twin earthquakes, suffered non-structural damage. The annual probable seismic loss is evaluated for both structures. The existing information of the seismic hazard of area and fragility curves of buildings were employed from previous research. The results indicate that although the initial cost of the project may increase due to application of base isolation, the overall probable loss is reduced due to lower vulnerability of the building equipped by such equipment.
Modelling and parametric study of self-centering reinforced concrete frame structures
Authors: Cui Ye , Lu Xilin , Jiang Chun
Published: March 2016

The beam-column and column-base connections of the self-centering reinforced concrete frames in this paper are allowed to open at beam ends and uplift at column bases by releasing the constraints, while rubber and prestressed tendons are introduced to ensure the self-centering of the structure. The seismic performance of the self-centering frames was investigated through nonlinear numerical modelling. Analytical models using OpenSEES are developed to study the seismic performance of the self-centering frames, and a parametric study is carried out. The parameters, such as the relative beam-to-column stiffness, rubber thickness, and the prestressed tendons on the behavior of the structures are investigated. Through this study, it is recommended to use relatively strong beams, more prestressed tendons, appropriately thick rubber blocks and prestressed tendons with proper positions to ensure the seismic performance and the self- centering capability of the structure.
Seismic Isolation of the existing viaduct B28 in Switzerland
Authors: Thomopoulos Constantinos
Published: March 2016

Inadequate earthquake resistance of existing bridges has been identified over the last years as a global engineering challenge, both for countries of high and of moderate seismicity, such as Switzerland. In this article the project of the seismic isolation of the Wysseflue-viaduct B28 at the Swiss national route A8 is presented as a case study of the suitability of this method for the protection of life and invested value of bridges with typical for Switzerland seismic deficiencies. Seismic isolation with low damping elastomeric bearings has been chosen as the technically most suitable and cost-efficient retrofit strategy, as retrofit costs do not exceed 3% of the estimated value of the structure.
Numerical Investigation of an RC Column Retrofitted with Steel Brace
Authors: Li Wencong , Kwon Oh-Sung
Published: March 2016

A novel seismic retrofitting method for an RC column is proposed in this paper. In the proposed retrofit method, both ends of an RC column are actively confined with steel plates and pre- tensioned high-strength external hoops. Then, a steel brace and the RC column are connected together to increase the lateral strength. The effectiveness of the retrofit technique was verified through cyclic lateral load tests. The experimental results show that the retrofitted specimen exhibits excellent seismic performance in term of strength while the non-retrofitted specimen failed in flexure-shear-critical manner. Numerical studies on the retrofitted and non-retrofitted specimens are carried out using OpenSees. For non-retrofitted specimen, shear spring element and shear limit curve are used to predict its shear-related hysteretic behavior. For retrofitted specimen, the buckling behavior of steel brace in compressive side is simulated and the sufficient ductility of steel brace in tensive side can be expected.
UHPFRC versus RC jackets for the seismic upgrade of columns
Authors: Lampropoulos Andreas , Paschalis Spyridon , Dritsos Stephanos
Published: March 2016

Strengthening Reinforced Concrete (RC) columns using jackets is a common technique used for the seismic upgrade of existing structures. In this study the effectiveness of traditional RC jacketing techniques is compared with the use of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) for the seismic upgrade of existing elements. Numerical models have been developed using ATENA Finite Element Analysis (FEA) and a parametric study has been conducted taking into account normal concrete to UHPFRC interface, and the differential shrinkage effect. The results of the parametric study indicate that the use of UHPFRC can considerably improve the strength and the stiffness of existing reinforced concrete columns.
Metro Grand Paris Express
Authors: Falcetto Pietro , Gellee Aymeric
Published: March 2016

This article traces out the different issues encountered while designing two underground stations on the Grand Paris Express Metro project. It also describes how our engineering team deals with urban and technical constraints, specific to confined areas all around Paris.
Structural Equation Modelling in Sustainable Human Settlement Research
Authors: Aigbavboa Clinton Ohis
Published: March 2016

Structural Equation Modelling (SEM) is a technique that effectively incorporates a whole range of standard multivariate analysis methods, including regression, factor analysis and analysis of variance. Using SEM, researchers can specify confirmatory factor analysis models. While being a sophisticated theoretical tool, and certainly not easy to implement, SEM underlies much of what sustainable human settlement (SHS) researchers do on a daily basis. That is, on the basis of things we can measure, and the attempt to make predictions of things we cannot measure. For SHS research, SEM provides an opportunity to hypothesise models of human behaviour, and to test or confirm these models statistically. The aim of this paper is to present how Structural Equation Modelling technique can be used to study and to understand issues encircling SHS issues with a specific emphasis on housing satisfaction in South Africa low-income housing. Research materials within and outside the field of the built environment were reviewed, and the researcher found that SEM using EQation modeling software (EQS) was the most appropriate technique for sustainable human settlement research studies. Because of the numerous benefits and advantages of the analysis produced by SEM through the EQS platform, such as the model estimation, and model fit attributes amongst others. The study further recommended the use of the process because of the Satorra-Bentler scaled statistics (S – Bχ2), use of appropriate cut-off values for the generated model analysis / fit Indices for various required goodness-of-fit tests of SEM model as applicable.
Temburong Bridge, Brunei – Ground Engineering - Part 2: Geotechnical Design
Authors: Ferrero Silvia , Leung Erin , Ngan Judy , Yin Kk , Yiu Jack , Evans Iolo
Published: March 2016

The new 30 km Cadangan Projek Jambatan Temburong (Temburong Bridge Project) in Brunei will provide a highway link between the two separated parts of Brunei, by spanning Brunei Bay. The complex geological setting brings particular challenges to the design and construction of the foundations required for the various forms of bridge structures. The varying depths of geological stratigraphy along the alignment and different loading conditions call for multiple deep foundation types, as well as different construction methodologies, to be adopted. Part 2 of this paper on the Ground Engineering aspects of the project focuses on the choices of foundation for different sections of the crossing, the geotechnical design approach and verification strategy, and the relevant computer analyses undertaken.
Temburong Bridge, Brunei – CC2 Marine Viaducts in Brunei Bay
Authors: To Murphy , Chong Yau-Hong , Luk Alice , Yiu Jack , Sangakkara Sunil , Wojnarski Lukasz
Published: March 2016

The new 30 km Cadangan Projek Jambatan Temburong (Temburong Bridge Project) in Brunei will connect the relatively isolated district of Temburong with the more developed Brunei-Muara district. The project includes over 14 km of marine viaducts crossing Brunei Bay which will be built under Construction Contract CC2.

The shallow waters of Brunei Bay, very soft ground conditions and a fast track programme pose significant challenges to both design and construction. Maximising the use of precast concrete and the repetition of details are key to delivering the scheme in an economical and timely manner.

The vast majority of foundations are groups of spun concrete piles. The superstructure will be in the form of twin post-tensioned concrete single-cell, box girders with 50m spans, built by span-by- span erection method.
Temburong Bridge, Brunei
Authors: Carter Matthew , Yip Sammy , Hussain Naeem , Chin Kok Kong , Ding Lee Sing , Lim Siew Long
Published: March 2016

Temburong district has been physically isolated from the rest of Brunei which has hindered the economic growth of the district. A sea-crossing is planned to link the district to Brunei-Muara. A feasibility study was carried out between 2010 and 2012 to establish the alignment and preliminary design of the link, assess the project impacts and analyse the costs and benefits.
Izmit Bay Suspension Bridge – Main Cable Anchorages
Authors: Pedersen Flemming , Christensen Søren , Jacobsen Jonas , Löhning Thomas
Published: March 2016

This paper describes the concept development and subsequent detailed design of the anchorages for the Izmit Bay suspension bridge with a main span of 1550 m. The significant variation in foundation conditions at the two ends of the bridge required completely different concepts for the anchorages. In particular at the south end of the bridge an innovative solution was developed where the main part of the anchorage was built within a huge excavation pit shaped like a "guitar" formed by 30 m deep diaphragm walls. As explained in the paper this solution was driven by the aim to safeguard against a potential secondary seismic fault occurring in the ground just below the anchorage. The long term durability and in particular the corrosion protection of the large number of post-tensioning tendons used to transfer the main cable tension to the bottom of the anchorages was a major concern. The paper describes an innovative solution based on use of dehumidification to deal with this challenge.
Buffeting response of long span bridges: numerical-experimental validation of fluid-structure interaction models
Authors: Diana Giorgio , Rocchi Daniele , Argentini Tommaso
Published: March 2016

Estimates of the buffeting response of long-span bridges rely on numerical models that require as input the dynamic finite element model of the bridge, the turbulence characteristics of the incoming wind, and the model for the fluid-structure interaction. Nowadays the first two inputs are reliable and do not require deeper investigations, but fluid-structure interaction models have margins for improvement in their accuracy. While from a numerical and analytical point of view these models have been developed and studied in detail, their experimental validation is still an open issue. Indeed, the numerical-experimental comparison is often done against the response wind-tunnel models, either full-aeroelastic or sectional models, which have some intrinsic limitations: for example, uncertainties related to the small geometrical scale for full-aeroelastic models, or the non-deformability of the deck in sectional models. To overcome some of the current limitations, in this paper a large-scale deformable aeroelastic model is proposed. The experimental results should be used as a benchmark study for the accuracy of numerical models for the buffeting response of long-span bridges.
Izmit Bay Suspension Bridge – Deep Water Tower Foundations
Authors: Pedersen Flemming , Christensen Søren , Jacobsen Jonas
Published: March 2016

This paper describes the concept development and subsequent detailed design of the deep water tower foundations for the Izmit Bay suspension bridge with a main span of 1550m. The foundation concept developed is an innovative design combining a traditional cellular concrete caisson with two cylindrical steel/concrete composite columns. Because the foundation concept is particularly optimized for resisting severe seismic loads the paper focusses on the required advanced modelling of soil-structure-interaction in relation to non-linear seismic time history analyses. The marine environment and deep water represents important challenges in relation to construction and long-term durability. The paper describes innovative solutions to deal with these challenges.
Izmit Bay Suspension Bridge – Finding and Consideration for Vibration control of Tower by Active mass damper
Authors: Inoue Manabu , Kawakami Takeshi , Takai Yusuke , Berber Oguz , Izawa Ryuki , Oizumi Satoshi
Published: March 2016

This paper presents the anti-vibration system to mitigate vibrations of the steel towers of IZMIT Bay Bridge in Turkey during the construction. The site performance tests have been carried out to ensure AMD performance. The comparison of the design assumption and the site measurement is made and possible future development is considered.
Recurrent laryngeal nerve injury following reoperative anterior cervical discectomy and fusion: a meta-analysis
Authors: Erwood Matthew S. , Hadley Mark N. , Gordon Amber S. , Carroll William R. , Agee Bonita S. , Walters Beverly C.
Published: March 2016

OBJECTIVE

Recurrent laryngeal nerve (RLN) injury is one of the most frequent complications of anterior cervical discectomy and fusion (ACDF) procedures. The frequency of RLN is reported as 1%–11% in the literature.4,15 The rate of palsy after reoperative ACDF surgery is not well defined. This meta-analysis was performed to review the current medical evidence on RLN injury after ACDF surgery and to determine a relative rate of RLN injury after reoperative ACDF.

METHODS

MEDLINE, PubMed, and Google Scholar searches were performed using several key words and phrases related to ACDF surgery. Included studies were written in English, addressed revisionary ACDF surgery, and studied outcomes of RLN injury. Statistical analysis was then performed using a random-effects model to calculate a pooled rate of RLN injury. The heterogeneity of the studies was assessed using Cochran's Q statistic and I2 statistic, and a funnel plot was constructed to evaluate publication bias.

RESULTS

The search initially identified 345 articles on this topic. Eight clinical articles that met all inclusion criteria were included in the meta-analysis. A total of 238 patients were found to have undergone reoperative ACDF. Thirty-three of those patients experienced an RLN injury. This analysis identified a rate of RLN injury in the literature after reoperative ACDF of 14.1% (95% confidence interval [CI] 9.8%–19.1%).

CONCLUSIONS

The rate of RLN palsy of 14.1% was greater than any published rate of RLN injury after primary ACDF operations, suggesting that there is a greater risk of hoarseness and dysphagia with reoperative ACDF surgeries than with primary procedures as reported in these studies.
Complications and safety of vagus nerve stimulation: 25 years of experience at a single center
Authors: Révész David , Rydenhag Bertil , Ben-Menachem Elinor
Published: March 2016

OBJECTIVE

The goal of this paper was to investigate surgical and hardware complications in a longitudinal retrospective study.

METHODS

The authors of this registry study analyzed the surgical and hardware complications in 247 patients who underwent the implantation of a vagus nerve stimulation (VNS) device between 1990 and 2014. The mean follow-up time was 12 years.

RESULTS

In total, 497 procedures were performed for 247 primary VNS implantations. Complications related to surgery occurred in 8.6% of all implantation procedures that were performed. The respective rate for hardware complications was 3.7%. Surgical complications included postoperative hematoma in 1.9%, infection in 2.6%, vocal cord palsy in 1.4%, lower facial weakness in 0.2%, pain and sensory-related complications in 1.4%, aseptic reaction in 0.2%, cable discomfort in 0.2%, surgical cable break in 0.2%, oversized stimulator pocket in 0.2%, and battery displacement in 0.2% of patients. Hardware-related complications included lead fracture/malfunction in 3.0%, spontaneous VNS turn-on in 0.2%, and lead disconnection in 0.2% of patients.

CONCLUSIONS

VNS implantation is a relatively safe procedure, but it still involves certain risks. The most common complications are postoperative hematoma, infection, and vocal cord palsy. Although their occurrence rates are rather low at about 2%, these complications may cause major suffering and even be life threatening. To reduce complications, it is important to have a long-term perspective. The 25 years of follow-up of this study is of great strength considering that VNS can be a life-long treatment for many patients. Thus, it is important to include repeated surgeries such as battery and lead replacements, given that complications also may occur with these surgeries.