bluuebunny/crossref_metadata_2025 huggingface dataset:
Wireless System for the Detection and Mitigation of Explosions in Tunnels
Authors: Marjanishvili S. , Chikhradze Mikheil
Published: February 2021

Physical security challenges from explosions are amplified in confined spaces. The air-blast shock waves reflect and propagate throughout the confined space. This paper describes the process of designing, constructing, and validating a wireless system for identification of explosions in real time. Protection of critical infrastructure requires the creation of a reliable system which provides quick and accurate identification of the hazards and subsequent transmission of the alarm signal to response and rescue services. The proposed wireless system consists of transmitter and receiver modules spaced throughout the tunnel. The transmitter module contains sensors and a microprocessor equipped with blast identification software. The receiver module produces an alarm signal and activation signal for the operation of protecting devices. The experimental validation has been carried out at the underground experimental base of G. Tsulukidze Mining Institute, Tbilisi, Georgia. The results of the testing validated the main characteristics of the system, notably:

No false signals were generated during the series of 20 experiments

After a blast event, the duration for analyzing the potential threat is 2.4 msec and the duration for activating the protection device is 11 msec

The reliable transmission distance is 150 m (492 ft) in a straight tunnel and 50 m (164 ft) in a tunnel with a 90° bend.
Application of Prestressed CFRP Textiles for the Development of Thin- Walled Concrete Structural Elements
Authors: Osman Letelier Juan Pablo , Hückler Alex , Schlaich Mike
Published: February 2021

The success story of prestressed concrete is based on the utilization of high‐strength prestressing steel which enables large compressive forces to be introduced into the concrete. However, thin‐walled concrete structures often require considerable thicknesses for the sole purpose of preventing corrosion of the steel elements. In this paper the use of prestressed Carbon Fiber Reinforced Polymer (CFRP) for the development of thin‐walled concrete structural elements is briefly presented. The transition of material to stronger, lighter and corrosion‐resistant CFRP represents a significant improvement in concrete construction. Prestressing with CFRP elements leads to more slender and thereby more economical and durable structural elements. Through the additional prestressing of a reinforcement mesh, very light and highly rigid surface structures can be constructed. Prestressing technologies have been developed and adapted for specific applications i.e. slabs and doubly curved structural elements and validated by experimental tests. This paper shows that prestressed carbon reinforced concrete can be used for more durable and efficient thin‐walled structures, allowing for more sustainable construction.
Precast Core Wall System for High-Rise Buildings
Authors: Carrion Juan E. , Baker William F. , Besjak Charles
Published: February 2021

The design of high-rise buildings is usually governed by lateral forces (e.g., wind or seismic). One of the most efficient structural systems to resist lateral loads is the core wall system. Traditionally high-rise concrete cores have been constructed using cast-in-place concrete, however precast systems offer an attractive alternative to cast-in-place construction. A precast concrete core wall system has been developed for high-rise buildings and will be presented in this paper. The main components of the system are the core walls, which are composed of multiple precast panels. The panel layout is determined based on the geometry of the tower and the capacity of the transportation and lifting equipment, while the wall thickness, concrete strength, and reinforcement are determined to satisfy strength and serviceability requirements. Several methods for connecting the panels have been developed, including combinations of embedded steel shapes, bolts, welds, and continuous reinforcing bars or post-tensioning. An application of the system to a 296 m (972 feet) tower in New York City is presented in this paper. This application demonstrates that the precast core wall system is an attractive and viable alternative to cast-in-place construction, capable of resisting the large forces associated with high-rise buildings, and with several advantages, including speed of erection, cost, as well as the high quality of precast concrete.
Longest Simple Span Steel Plate Girder Bridges in Florida – I-75 over SR 50 Twin Bridges
Authors: Rodriguez Leo , Sinson Henri
Published: February 2021

Throughout the nation, solutions to accommodate increased traffic and limited right-of-way have required innovative interchange configurations. These interchanges have posed many challenges in the development of structural solutions. This paper discusses the structural and construction solutions for the replacement of the I-75 bridges over SR 50 with new steel bridges to satisfy the geometry of a new Single Point Urban Interchange (SPUI) in Florida.
Intermeshing: A New Concept For Rapid Steel Erection
Authors: Al-Sabah Salam , Laefer Debra , Truong-Hong Linh
Published: February 2021

Three-dimensional intermeshing of steel enabled by advanced digital manufacturing holds the potential to radically change how steel bridges and buildings are connected. This paper presents the concept of the first universal structural steel connection in over 100 years. The proposed Intermeshed Steel Connection (ISC) exploits recent advances in steel cutting technologies and robotics to shape member ends precisely. This vastly reduces on-site bolting and welding. Forces are transferred through common bearing surfaces at multiple contact points. The new connection is designed to accelerate structural steel deployment and offer better disassembly options. This paper introduces the geometry, manufacturing, and initial analysis of the connection approach, which holds the potential to be robust, secure, scalable, and faster to erect.
Why the 200-year bridge is a myth - a new perspective towards an evolving structure
Authors: Gabler Markus
Published: February 2021

When we design bridges for 100, 120 or even 200 years we have a static use case in mind. We design for one given traffic load - maybe increased 10% for the future - and anticipate virtually no adjustments in use and structural behavior, except for some bearing or cable replacement features. Looking back how demands changed even within the last 50 years, it would be naive to anticipate we know what is required in 200 years. Also - the effort spent in maintenance and refurbishment is significant during its service life.

We should think of bridges as living or evolving things. And digitization can help! A structural health monitoring system (SHMS) is necessary to better understand needs for strengthening and repair. A site-specific traffic analysis will show how demands change regarding means of transport and loads. Also, a "living" BIM model which will be maintained and nurtured during the whole life of a bridge is an important step to get a clear overview "how it goes" and what will be required next. Finally – the structural system of a bridge should allow for easy replacement of components, widening or re-use elsewhere. Modular construction would be a key element to allow for better adaptability.
Towards 2222, science fiction or an educated guess for the design of bridges?
Authors: Vergoossen Rob
Published: February 2021

About 200 years ago the first railroad bridges were build, followed almost 100 years later by bridges for cars and trucks. Since the first cars and trucks, traffic has changed. Up to now this change is mostly an increase in intensity and axle and gross vehicle weight of trucks. But soon mobility will change.

When designing a bridge for a lifespan of 200 years there are a lot of uncertainties to deal with.

Will there be more vehicles due to easier transport, or will there be less because of a reducing population, virtual reality and robotics? There are a lot of construction activities going on in the world, but when will this change and what is the impact on mobility and transportation? The innovation in technology will change the use of the transport, which will make it more efficient, but is this also efficient for bridges? And what will be the effect of renewable energies and reducing CO2 on the usage of bridges? A lot of unknowns and only future will tell us what exactly will happen.

In this paper we give some scenarios on possible changes in the near and far future and how this can possibly influence the way we design our bridges today.
Great open spaces for emergency covered with Hemp cables nets
Authors: Taddeo Chiara , Di Giovanni Marco , Viskovic Alberto , D'Asdia Piero
Published: February 2021

Emergencies like post hurricane or earthquake need of buildings quick and easy to build. These buildings have to be great open spaces in order to host as many people as possible. These buildings can be non-temporary because they are useful for one, two years or more. For this reason, they have to be designed like permanent buildings. This exclude a great number of typologies as for example inflatable structures. The typology suggested is cables net and membrane roofs with hyperbolic paraboloid shape. These typology permits to cover very large span and it is built easily and quickly. In order to encourage a sustainability approach to build, the paper promotes recent developments in the field of material engineering that have allowed for the use of natural materials for common structural elements instead of traditional materials such as steel or concrete. In this context, hemp is a very interesting material for structural building design. This paper proposes the use of hemp cables for roofs with hyperbolic paraboloid cables nets, which sees the use of a sustainability material for structure thus having a very low environmental impact in terms of structural weight. The paper discusses five different plan sizes and two different hyperbolic paraboloid surface radius of curvatures. The cable traction, which gives the cable net stiffness, was varied in order to give a parametric database of structural response. Three-dimensional geometrically nonlinear element analyses were carried out on different geometries and a parametrization of the borders structures of anchorage is given.
Low-cost affordable single family housing in Poland. Light steel frame as an alternative construction solution
Authors: Kozłowski Aleksander , Siwowski Tomasz W. , Kozłowski Tomasz
Published: February 2021

Conventional single family houses in Poland are being built in the improved traditional construction technology with massive load-bearing structure created by masonry walls made of ceramic, silicate or aerated concrete blocks, concrete foundations, concrete rib-and-slab floor and pitched timber or concrete flat roof. Expanded polystyrene and mineral wool are being used as thermal insulation. Such solution is very time- consuming and costly due to more and more expensive manpower. The change in economy from communism to free market caused the beginning of modern thinking about construction technology for family house to be light, eco-friendly, innovative and low-cost. The definition of the term “affordable” in relation to single family housing, as well as the socio-economical background for the low-cost housing in Poland is presented. The paper presents proposal of low-cost family house construction built in light steel frame technology. The supporting structure is composed of steel frame made of cold-formed galvanized C shape profiles. Externally the steel frame is covered with cement bonded particle boards, covered with polystyrene insulation and finishing coat according to ETICS system. From the inside the steel frame is covered with plasterboards. The main thermal insulation of the building is created by mineral wool filling the interior spaces of walls, ceiling and roof panels. Comparison of the total construction costs of a 136 sq m building made in light steel frame technology with buildings of identical dimensions made in other, popular and available traditional technologies showed that a steel technology is approx. 10-20 percent cheaper. The paper presents also the comparison of the low-cost model steel structure houses worked out in Czech Republic, Portugal, Romania and Brazil, including technical parameters, structure type and cost of erection.
C-section Cold-Formed Steel as Structural Members in Housing Construction in the Philippines
Authors: Lejano Bernardo A.
Published: February 2021

Getting good lumber for housing construction is becoming difficult in the Philippines due to existing partial log ban. Although, the use of reinforced concrete is still the most popular in construction, an emerging alternative is the use of cold-formed steel (CFS). It is gaining popularity because of its high strength-to- weight ratio. However, information about the structural performance of locally-produced cold-formed steel is almost nonexistent. Although, design provisions are stipulated in the local Code, these are based on formulas developed abroad, hence the need to investigate these cold-formed steel. This study focuses on the C-section cold-formed steel, which is the most popularly used. The objective is to verify its performance when subjected to axial compression and flexure, both experimentally and computationally. For the computational part, the formulas stipulated in the National Structural Code of the Philippines were followed. For the experimental part, the cold-formed steel members were subjected to compression loads and flexural loads. Aside from usual sensors, high-speed cameras were used to capture the failure modes. For axial compression test, 80 specimens with different lengths and thicknesses were tested. For flexure, 24 specimens of back-to-back C-sections were subjected to 4-point bending test. Results showed the predicted strengths were well below the experimental values. In design, this means the use of Code-based formulas is conservative. Failure modes observed were torsional buckling and distortional buckling. Comparison of failure modes between experiment and computation shows 70% agreement for compression and 75% for flexure. Finite element method calculations were also done and were compared with experimental results.
Revisiting Low Income Residential Construction Options in Spokane
Authors: Milacek McKenna S. , Schultz Joshua , Muszynski Mark
Published: February 2021

Affordable housing plays an important role in providing equal opportunity for individuals within most communities in the United States. In the area of eastern Washington State, in particular, there is currently a dearth of affordable housing options; especially for larger families. This lack of three- and four- bedroom residences presents a challenge for the City of Spokane, and the low-income residents seeking housing. This paper provides a preliminary look at certain alternate construction approaches for stand-alone houses with the end goal of optimizing taxpayer funding available, and to reduce living expenses for occupants. Two possible alternative approaches [structural insulated panels (SIPs) and straw bale wall construction] are compared to traditional wood frame construction; all in terms of cost and structural performance. Alternate foundation options are also currently under consideration. It appears that certain alternate construction techniques are worthy of a fresh look; particularly straw bale construction.
New construction ideas for special housing complexes
Authors: Mola Franco , Migliacci Antonio , Mola Elena , Antelo Alejandro Erick , Soffientini Riccardo
Published: February 2021

The problems concerning the design, construction and use of buildings in a city environment or even other, less dense, environments, constitute a complex scenario in which various different disciplines are called to give their contribution: energy efficiency, reduction of the footprint, comfort, affordability and new living standards all play a key role in the design of new housing solutions. In the present paper, a new design idea is presented for the construction of buildings, capable of guaranteeing a high level of comfort for the users while safeguarding the surrounding territory. The proposed system, named GEODE, consists of a 120m diameter spherical steel or concrete structure with internal cores acting as shear-resistant elements. The shell contains five decks supported by mega-beams, on which 5-story high buildings can be erected, following design guidelines that have as a primary objective the preservation of high livability conditions. Among the defining characteristics of the system are its enhanced performance with respect to buildings of equal volume but different shape and the possibility of building the spherical shell using two different structural materials. These are distinctive features, which allow for the construction of small self-sufficient cities that synergically interact with their surrounding environment. In the present paper, an initial feasibility study is presented while the performance of different possible structural solutions, i.e. using R.C. or steel elements, are compared.
Urban Infrastructure: The Signature Cable-Stayed Bridge in Delhi
Authors: Schlaich Mike , Burkhardt Uwe
Published: February 2021

To relief the heavily congested north-eastern access to the metropolis of Delhi a new eight-lane bridge across the Yamuna river was required. The new bridge shall not only resolve the traffic problem but in a holistic approach become a new landmark for the northern part of Delhi and the seed of a new recreational area along the cleaned and recultivated Yamuna shores.

A single-pylon cable-stayed bridge now crosses the Yamuna river bed with a main span of 250 m to leave ample space for the future lake created here. The inverted Y-shaped pylon with a height of 150 m is leaning backwards to counterbalance the weight of the composite deck above the river. Also, the two cable planes of the main span are merged in the pylon to a central cable plane that leads to the backstay anchorages. The outcome was a uniquely shaped, origami-like pylon that is topped by a glass tip to act as a beacon at night.

The combination of a robust composite concrete deck with a prefabricated steel pylon made such a design feasible in the seismic area of Delhi. The bridge is equipped with an advanced monitoring system to ensure its anticipated durability into the next century.
Potential Insights from Performance-Based Design of Fire Protection in Tall Buildings
Authors: Ghisbain Pierre , Sideri Jenny , Abbasi Reyhaneh , Balsamo Luciana , Imani Reza , Ashrafi Ali
Published: February 2021

Analysis of the structural performance under realistic fire scenarios makes Performance Based Fire Engineering (PBFE) particularly suited to design fire protection of tall buildings. In this paper, the impact of using the PBFE method is studied using a standard tall building as an example. The parametric temperature- time curves recommended in Eurocode 1 are used to define the fire loads. The thermal and mechanical response of the building to the imposed fire loading is subsequently analyzed by means of a finite element model of the mixed-use tower. Particular care is devoted to analyzing the performance of a steel truss at a transfer level, to study potential global effects of a local fire, effects that are not studied or understood within the prescriptive design framework.
Demonstrating Performance-Based Fire Design of Composite Buildings
Authors: Gernay Thomas , Khorasani Negar E.
Published: February 2021

Performance-Based Fire Engineering (PBFE) is gaining traction in the US, with the aim to provide safe, resilient and cost-effective design solutions for structural systems in our evolving communities. Steel-framed buildings with composite steel-concrete floors are widely used in practice and offer opportunities for achieving robust fire performance through PBFE. This paper demonstrates the design process, computational modeling approaches, and main assumptions for PBFE of steel-concrete composite buildings using a streamlined and systematic methodology. Performance expectations are explicitly spelled out at the outset of the process. A set of design fires are generated using zone models based on high percentiles of the fuel load. Then, the thermal-structural response is modeled using nonlinear finite element analyses. Design alternatives are evaluated against the predefined performance expectations. While the prescriptive code design does not survive until burnout, PBFE alternatives can survive the fire, adopting selected structural upgrades and an optimized allocation of the thermal insulation on the steel members. The activation of tensile membrane action in the fire-exposed composite floor is captured by the model. Single bay models are compared to full building models, showing the beneficial contribution of the system restraints provided steel mesh continuity is ensured over the girders. Thus, the single slab model provides conservative results at lesser computational cost. The full building model allows investigating robustness under extreme scenarios such as multi- compartment fires or multi-hazard scenarios with fire following a column loss. Adoption of this design process by structural fire engineers can lead to robust PBFE designs with explicit evaluation of the response under a range of extreme events, for a demonstrated performance level that is pre-agreed between the stakeholders.
Aerodynamic Shape Tailoring of Buildings: A Fusion of CFD, Stochastics, Machine Learning and Beyond
Authors: Kareem Ahsan , Ding Fei , Wan Jiawei
Published: February 2021

Tall buildings exposed to wind undergo complex interactions, which precludes a functional relationship between wind and ist load effects. Accordingly, wind tunnels have traditionally served as a means of quantifying wind loads. In digital age with burgeoning growth in computational resources and parallel computing advances in computational fluid dynamics, computational simulations are evolving with a promise of becoming versatile, convenient and reliable means of assessing wind load effects. The major challenge to such an initiative has been the wind field around the structures marked by separated flows, which requires high fidelity simulation schemes to capture extreme loads, thus placing a high demand on computational resources. The emerging trend is to use a combination of CFD, stochastic emulation and machine learning approaches to overcome some of these challenges.

This paper will utilize this digital simulation approach to mitigate motion of tall buildings through shape morphing. It will illustrate a practical example involving shape optimization of buildings. To go beyond static optimization to mitigate wind effects, a brief overview of the fusion of sensing, computations and actuation in a cyberphysical space to autonomously morph structures to adaptively undergo shape changes in response to changes in coming wind conditions will follow.
Use of Integrated Viscous Dampers to Control Wind Induced Vibrations in Tall Buildings
Authors: Ashcroft Ian , Burton Melissa , Farnsworth David
Published: February 2021

The tall building world is seeing a trend pushing building heights and slenderness ratios to levels previously unseen. The design of these buildings for both strength and serviceability is typically governed by the dynamic response of the building to wind. Comfort of building occupants during relatively low return period wind events is a key challenge, and engineers are increasingly turning to damping technologies to limit building accelerations rather than adding stiffness or mass. Large tuned mass dampers (TMDs) are a commonly used solution.

This paper suggests that integrating viscous dampers within a tall building’s structure can deliver a cost- effective alternative to TMDs, delivering high performing buildings with additional benefits in terms of robustness and space efficiency.

Two case studies are presented. Firstly, measured data from a tower in New York with viscous dampers integrated into the structure is provided, comparing design stage predictions to real-life performance. Furthermore, a case study for a super-slender tower is described, demonstrating the potential for enhanced performance and significant cost and space savings using integrated damping.
Interrelation of Architectural Form and Wind Climate on the Wind Performance of Supertall Towers
Authors: Devin Austin F. , Kulkarni Aditya P. , Young Bradley S. , Baker William F.
Published: February 2021

The architectural form of tall and supertall buildings is a fundamentally influential factor in the building’s wind response. Under the action of wind, a tower’s shape can significantly influence the building’s occupant comfort levels, serviceability performance, as well as the effective wind loads which a structure must resist. As tall buildings advance to ever-increasing heights and, more recently, unprecedented slenderness ratios, the across-wind response, or lift response, of towers due to vortex shedding becomes the predominant contributor to wind response. The frequency and intensity of vortex formation off a bluff body is a function of the shape and width of the bluff body, and the speed of the flow. This is a critical relationship in wind engineering where fluid dynamics and architecture intersect, and is defined by the powerful Strouhal equation [1]. This paper shall investigate wind response as a function of the interrelation of the Strouhal number parameters with the structure’s own dynamic properties, as well as the wind environment in which the building is located. In addition, the potential benefit of Critical Width and Critical Mean Recurrence Interval plots as initial indicators at the conceptual stage of tower design will be highlighted.
Adaptive TMD System for Reduced Space Demand in Tall Buildings
Authors: Weber Felix , Huber Peter , Spensberger Simon , Okumusoglu Deniz , Distl Johann , Braun Christian
Published: February 2021

Tuned mass dampers (TMDs) are widely used to mitigate wind-induced tall building vibrations. However, two major disadvantages of passive TMDs exist. The installation height of pendulum TMDs consumes expensive space and passive TMDs cannot cope with the time-varying excitation frequency of wind loading which will excite several structural modes. Also, the pendulum mass may impact the structure due to seismic excitation which necessitates huge snubbing systems. The presented adaptive TMD System addresses all these shortcomings. The installation height is reduced by up to 50 % by the inclination of the pendulum cables as this method enlarges the radius of the pendulum mass center being equivalent to the reduction of the natural pendulum frequency. The efficiency of the adaptive TMD is improved by adjusting the oil damper characteristics in real-time which allows reducing the pendulum mass up to 20 %. The overdamping control approach activated at wind return periods greater than 10 years reduces the maximum pendulum relative motion by up to 25 %. The adaptive TMD with inclined cables therefore minimizes the installation space which helps to maximize the economic benefit of the building.
Finite Element Model Updating for a Suspension Bridge Using Deep Neural Networks
Authors: Park Wonsuk
Published: February 2021

The finite element model for the performance evaluation of an existing structure should be able to accurately reflect the current state of the structure. As one of popular methods, the dynamic finite element model update finds the optimal parameters for the finite element model closest to the measured modal frequencies and shapes by using error minimization procedures. In this study, we propose a new method to construct an inverse eigenvalue problem that can directly obtain the parameters of the finite element model from the measurement modal information by developing a deep neural network to solve the inverse eigenvalue problem quickly and accurately. The solution of the inverse eigenvalue problem is obtained by using the mode frequencies and shapes measured as the input of the network and using the corresponding model parameter as the output. As an application example of the developed method, the dynamic finite element model update of a suspension bridge for given response data is presented. Unlike the existing update method based on the optimization procedure, this method can be updated in real time, and various update solutions considering the measurement error can be easily obtained.
Structural Health Monitoring of RC structures using optic fiber strain measurements: a deep learning approach
Authors: Karypidis Dimitrios F. , Berrocal Carlos G. , Rempling Rasmus , Granath Mats , Simonsson Peter
Published: February 2021

This paper reports the early findings of an ongoing project aimed at developing new methods to upgrade the current maintenance strategies of the civil and transport infrastructure. As part of these new methods, the use of Machine Learning (ML) algorithms is being investigated to constitute the core of a new generation of more accurate and robust structural health monitoring (SHM) systems for concrete structures. Unlike most of the existing SHM systems, relying on the analysis of the natural frequencies of the structure based on data obtained from accelerometers, the present study uses a distributed optic fiber system to monitor the strain distribution along steel reinforcing bars. The preliminary results of the study indicate that a semi-supervised Deep Autoencoder algorithm (DAE) can successfully quantify the damage attributable to transverse cracks in a reinforced concrete beam subjected to three-point loading. Future applications will feature the determination of crack locations, early detection of reinforcement corrosion as well as other types of damage such as splitting cracks or surface spalling.
An Integrated Framework for Seismic Risk Assessment of Reinforced Concrete Buildings Based on Structural Health Monitoring
Authors: Sheikh Imran Ahmed , Khandel Omid , Soliman Mohamed , Haase Jennifer S. , Jaiswal Priyank
Published: February 2021

In recent years, several locations in the United States have been experiencing a significant increase in seismicity that has been attributed to oil and gas production. As oil and natural gas production in the United States continues to increase, it is expected that the seismic hazard in these locations will continue to experience a corresponding upsurge. However, many urban structures in these locations are not designed to withstand these increasing levels of seismicity. Accordingly, it is crucial to develop methodologies that can help us quantify the seismic performance of these structures, establish their risk levels, and identify optimal retrofit strategies that will enhance the seismic resilience of these structures. In this context, structural health monitoring (SHM) plays an important role in understanding the seismic performance of structures. SHM can be used, in conjunction with finite element modelling, to provide a realistic representation of the structural performance during a seismic event. In this paper, a framework for seismic risk assessment of reinforced concrete buildings based on SHM is presented. The framework combines nonlinear finite element modeling and SHM data to establish the seismic fragility profile of the structure. The approach is illustrated on a multi- story reinforced concrete structure located on the Oklahoma State University Campus.
Weather Forecasting Technology Applied to Structures Improves Resiliency
Authors: Chapman Ron J. , Taylor Zach J.
Published: February 2021

Designers are creating taller and more complex structures in the urban built environment. These complex structures include long span bridges, buildings and monuments all of which can push the limits of design and engineering processes. These structures are challenging to construct, operate, and rehabilitate during their life-cycle. Analytics used during the design phase can be combined with weather forecasting technology to provide an advanced site and structure-specific weather forecast. This site and structure-specific weather forecast helps to ensure efficient, safe construction, and maximizes operation of the structural asset. Examples discussed include forecasting of wind conditions for construction/maintenance activities on bridges, prediction of falling snow/ice accretion from cable stay bridges/buildings and prevention of high-sided vehicle blow over on bridges. Analysis of weather forecasting data combined with a historical database of site-specific weather monitoring provides knowledge about deviations from the normal climate. This analysis can provide advanced storm warning thereby mitigating potential damages. The ability to provide site-specific and structure-specific weather forecasts is increasingly important because of the increased intensity and frequency of storm events due to climate change.
Predicting the change of hydraulic loads on bridges: a case study in Italy with a 100-year database
Authors: Pucci Alessandro , Sousa Hélder S. , Matos José C.
Published: February 2021

Planet Earth is naturally subject to climatic variability, but over the recent decades extreme deviations have been observed. Climate change, as a manmade-induced process, is mainly due to the increase of greenhouse gasses emission. Global warming consequences drive also to an intensification of hydrological cycles, leading to more frequent and severe precipitations. In parallel, several bridges have collapsed in the last years due to extreme rainfalls. Although the impacts of climate change on built environment do not always present a direct cause-effect relation, analysis on specific parameters (as rain volume) that are inputs in bridge design, can clarify some aspects of this interaction. In this paper, the peak discharge variation of different rivers located in the northwest of Italy, within the last 100 years, is analyzed. A cluster analysis was performed to understand if the hydraulic design loads should be considered with a different intensity if the bridge had been built with reference to an up-to-date database, or if in the last decades, when the majority of these structures were built. The rainfall data was analyzed through classical techniques, such as the frequency-based statistical method, but without the stationary time hypothesis. In this case, the extreme value theory was used for the estimation of intensity-duration curve parameters. By introducing a second-order analysis, where random variables can change over time, an increase-trend of rainfall height was found, and the peak discharge was determined accordingly. The relevant parameters on the case-study area were preliminarily obtained through geographic information systems. The results evidenced that nowadays-floods parameters are significantly different from those of the past, and this behavior is escalated when high return period values are assumed. Furthermore, although hydraulic design loads are increasing, many existing bridges are not properly maintained, leading to an increased number of collapses.
Blast Mitigation Design for Urban Steel Structures Subjected to Close- in Detonations
Authors: Kim Yongwook , Rooney Jarett
Published: February 2021

More frequent terrorist attacks to civilians, buildings, and infrastructures have been observed in recent years, which occasionally resulted in significant fatalities, financial damages, and service interruptions due to collapses of the structures. The collapse of a structure can be triggered by substantial or complete damages of essential structural members, potentially resulting from close-range detonations. Close-range detonations can be fatal even with a small portable charge weight. Many structures in major international cities are potentially exposed to close-range detonations, simply because there is no room to maintain a sufficient stand-off distance around each structural member. Current available approaches to blast resistant designs are focusing on far-range detonations; for close-range detonations, a non-linear explicit finite element analysis is required, instead. Most structural engineering firms do not have access to the analyses, because the details of the analysis are not readily available. In the present study, some details of the non-linear explicit finite element analysis are presented for close-range detonations. The same method is applied to numerical parametric studies for a standard steel column subjected to a range of charge weights and stand-off distances. In the study, the development of a performance-based engineering chart is discussed, which can be used by general structural engineers without performing the numerical analysis. A few practical strengthening layers of steel members are also investigated to effectively mitigate potential damages from close-range detonations.
Dynamic behavior of an innovative replaceable pier structure under lateral impact loadings
Authors: Liu Chengdong , Wang Junjie , Song Yanchen
Published: February 2021

In order to improve the repair efficiency of bridge piers subjected to vehicle and ship collisions, an innovative replaceable pier structure based on flange connection and PBL shear connector was proposed. The finite element model of the replaceable pier and the traditional pier were developed and then validated through experimental test results. The behavior of replaceable pier and connection joint under lateral impact loading was studied based on numerical simulations. Compared with the traditional pier, it shows that the ability of new replaceable pier to resist impact loading is more favorable, and the connection component of new replaceable pier is repeatable.
Finite element modeling of concrete beams reinforced with basalt FRP bars
Authors: Carter Jordan , Genikomsou Aikaterini
Published: February 2021

Fiber-reinforced polymer (FRP) bars can replace conventional steel reinforcing rebars to prevent from corrosion in reinforced concrete structures exposed to highly corrosive environments. In this contribution, three tested concrete beams reinforced with BFRP (Basalt Fiber Reinforced Polymer) bars are analyzed using three-dimensional finite element methods. In the numerical analyses, concrete is modeled as nonlinear using plasticity and damage principles, while BFRP is modeled as linear elastic material. The main focus of this research is to present the calibration process that should take place prior to any parametric studies. This calibration suggests that the concrete model should be regularized using a characteristic length and material post-yield fracture energies in both tension and compression to provide mesh-size independent results. The numerical results are compared to the test results with regard to failure load and cracking.
Punching Shear Capacity of Steel Fiber Reinforced Concrete Slab- Column Connections
Authors: Landler Josef , Fischer Oliver
Published: February 2021

To design flat slabs directly supported on columns, the punching shear resistance of the slab is a main factor. It can be increased in the vicinity of the slab-column connection with punching shear reinforcement, like bent up bars or shear studs, to bear the high reaction forces. However, the usage of punching shear reinforcement requires the knowledge of special design rules and often leads to problems and deficiencies in construction.

Fiber reinforced concrete seems to be a promising alternative to conventional punching shear reinforcement. To investigate the load bearing behavior of the slab-column connection using fiber reinforced concrete, a total of eight punching shear tests were performed. The specimens were realized with a typical top and bottom flexural reinforcement, but without punching shear reinforcement. Varied parameters were the slab thickness with 250 mm and 300 mm and the fiber content Vfwith 0.5 Vol.-% and 1.0 Vol.-%. To investigate the influence of modern fiber types, normal- and high-strength steel fibers with normal- and double-hooked-ends were used.

In all eight experimental tests, the intended punching shear failure was achieved. The capable load using fiber reinforced concrete increased by 20 % to 50 % compared to the reference tests without steel fibers, depending on the fiber type and the fiber content Vf. Additionally, this load increase was accompanied by a significant improvement in ductility. The post-cracking behavior was noticeably influenced by the used steel fiber type. An influence of the slab thickness or steel fiber type on the shear strength contributed by the fiber reinforced concrete could not be determined.
Exploring the Potential Use of GFRP Bars in Earthquake-Resistant Concrete Structures
Authors: Auman Hayato , Palermo Alessando , Worner Victoria , Scott Allan
Published: February 2021

The corrosion of steel reinforcement is a persistent issue plaguing concrete structures today. The availability of non-corrodible fiber-reinforced polymer (FRP) reinforcement presents an opportunity to mitigate or even eliminate the issue of corrosion, however there is minimal uptake of these bars specifically in seismic applications due to their brittleness. Glass FRP (GFRP) bars, being one of the more common and economical of the FRP products, is being explored at the University of Canterbury for its potential use in earthquake- resistant design. In particular, the cyclic bond of GFRP bars with concrete is being tested using a modified RILEM beam bond test to determine whether they are able to maintain adequate bond with concrete under seismic loading. This paper will discuss the potential use of GFRP bars in seismic applications, drawing form work around the world, and introduce the salient features and behavior of cyclic bonding of GFRP bars as preliminary observations from the bond tests conducted.
Numerical study on bonding strength of ribbed reinforcing bars in UHPC with material ductility
Authors: Shi Xuefei , Gao Yi , Cao Shenghui
Published: February 2021

This paper mainly studies the bonding mechanism of ribbed steel reinforcing bars in ultra-high performance concrete (UHPC) considering the influence of material ductility. In recent years, the bond slip behavior of reinforcing bars in UHPC has received extensive attention. In the previous pull-out tests, it was found that the classical splitting theory still plays role in bond failure modes. In this paper, the pull-out test is simulated by finite element analysis, and it is found that unlike ordinary concrete, UHPC can still hold the load for a period of time after the tensile stress on splitting surfaces reaches the critical value, due to the ductility of the material. It is found from the numerical results that the bonding stresses are not evenly distributed along the steel bar when the pull-out failure occurred. Through theoretical analysis and experimental verification, the maximum bonding force of ribbed reinforcing bars in UHPC is closely related to the material ductility. Based on this, a new theoretical model for calculating the bonding strength of ribbed steel reinforcing bars in UHPC is proposed, and can be used for the design method of urban bridge built with UHPC.
Strain monitoring on pre-stressed CFRP laminates through computer vision
Authors: Santos Bruno , Valença Jónatas , Dourado Filipe , Júlio Eduardo
Published: February 2021

Strengthening reinforced concrete (RC) members with Carbon Fiber Reinforced Polymer (CFRP) solutions is currently a widespread technique. The success in increasing the strength and/or in controlling the deformation of structural members using CFRPs has been recognized worldwide, and most relevant aspects have been thoroughly studied and published. For large-span beams and slabs, the method is much more effective if pre- stressed CFRP laminates are adopted. Therefore, onsite measurements of the applied strain state, as well as of its evolution with time due to pre-stress losses, are mandatory to ensure a correct operation and to monitor the time-dependent behavior. Presently, the former is assessed only indirectly, through load control when pre-stress is applied, and the latter simply is not conducted since there is no budget to comply with.

In this paper a first step of a vision-based method to measure the strain level in CFRP laminates during the strengthening operations, as well as during periodic inspections later on, is presented. The method uses computer vision and was applied and validated in computational simulations. The results achieved allowed to establish the limits of validation of the algorithms developed and implemented. The contactless method proposed will represent a major added value for the already widespread technique of reinforcement of RC members with pre-stressed CFRP laminates.
Statistical survey of existing reinforced and pre-stressed bridge types for the AT-CZ region within the "ATCZ190 SAFEBRIDGE" Project
Authors: Apostolidi Eftychia , Šomodíková Martina , Strauss Alfred
Published: February 2021

Advanced modeling of structures using combination of non‐linear finite element methods (NLFEM) and reliability analysis is a strong tool for realistic assessment of structures. NLFEM simulation has been recently a well‐established approach to the analysis of concrete structures since the response of the structure can be simulated quite realistically. In combination with fully probabilistic approaches, one can consider the randomness of input parameters such as material, technological and environmental characteristics that can have a direct impact on economic aspects during structural lifetime. However, guidelines fully describing NLFEM modeling of structures and safety formats are not available until now. In the framework of the European Project INTERREG AUSTRIA‐CZECH REPUBLIC "ATCZ190 SAFEBRIDGE", a number of existing bridges are carefully selected to be studied and modeled with NLFEM on deterministic and stochastic levels based on the upcoming Austrian standard ON B4008‐2. The assessment of structures will be described and documented in detail and the results will assist the development of a guideline. This guideline targets to help the engineering community perform accurate NLFEM analysis and to assist the structure's owners to check the accuracy of the assessment process. The current paper focuses on the presentation and discussion of statistical information about road and railway bridges provided by the main bridge operators in both countries. Moreover, the most commonly addressed structural characteristics of bridges within the program region are summarized and the further future steps of the project are briefly described.
A new method for cable shape finding of self-anchored suspension bridges
Authors: Liu Chao , Gao Zhan
Published: February 2021

This paper proposes a new overall coordinate method (OCM) to determine the cable shape of self-anchored suspension bridges. In this method, the initial cable shape between adjacent clamps is assumed to be linear and the target cable shape is calculated by iterations based on the overall equilibrium of forces. This method is used to calculate the cable shape of the Chishui Bay Bridge in Hebei Province by MATLAB, and the results are compared with the measured data. The comparison shows that the OCM has a fast convergence speed and high accuracy.