Short-span Bridges Research Articles

Crowdsourcing bridge dynamic monitoring with smartphone vehicle trips

Monitoring and managing the structural health of bridges requires expensive specialized sensor networks. In the past decade, researchers predicted that cheap ubiquitous mobile sensors would revolutionize infrastructure maintenance; yet extracting useful information in the field with sufficient precision remains challenging. Herein we report the accurate determination of critical physical properties, modal frequencies, of two real bridges from everyday vehicle trip data. We collected smartphone data from controlled field experiments and uncontrolled Uber rides on a long-span suspension bridge in the USA (The Golden Gate Bridge) and developed an analytical method to accurately recover modal properties. We also successfully applied the method to partially-controlled crowdsourced data collected on a short-span highway bridge in Italy. Further analysis projected that the inclusion of crowdsourced data in a maintenance plan for a new bridge could add over fourteen years of service (30% increase) without additional costs. Our results suggest that massive and inexpensive datasets collected by smartphones could play a role in monitoring the health of existing transportation infrastructure.

WATER-REPELLANT EFFECT OF REINFORCED CONCRETE (RC) BEAM COATED WITH A SURFACE-PENETRANT

Concrete coated with surface-penetrant is an efficient method to improve durability because it can decrease the ingress of deterioration factors such as water and chloride ions. Our previous study had focused on a silane-based penetrant having high water-repellant effect and examined the freeze-thaw (F-T) durability of the concrete coated with the penetrant. As well as F-T action, the water-repellant effect must decrease the possibility of deterioration related to water and chloride ions ingress. It is well known that water in pore of concrete is a compromising factor to decrease the fatigue durability of RC structures. The effect of surface-penetrant may be significantly varied by microscopic pore structures in concrete. Hence, the study prepared concrete cylinders and RC beam specimens made by wide range of water-cement ratios (w/c) from 0.55 to 1.0. Noting that the low-strength concrete made by the w/c = 1.0 is very unusual for structural concrete. However, such low strength properties are occasionally observed in short-span RC bridges constructed in 1960s or earlier. Hence, the study examined the effect of the surface-penetrant by using various w/c concretes. The paper reports the fundamental investigations of penetration depth and fatigue durability of the coated RC beams.

Effect of Temperature on the Modal Variability in Short-Span Concrete Bridges

The dynamic characteristics of bridges are known to be affected by damages as well as by environmental factors such as temperature. Therefore, the changes in the dynamic characteristics caused by damages and environmental factors should be considered when evaluating the health of the structure. Accordingly, this study conducted long-term monitoring and modal identification of short-span concrete bridges, i.e., a RC (reinforced concrete) slab bridge a RC rahmen (rigid-frame) bridge. The investigation revealed that temperature is the factor having the greatest influence on the variability of the dynamic characteristics as the natural frequencies of the bridge decrease with higher temperatures. Model updating verified that such modal change resulted from the temperature dependency of the elastic modulus of concrete. The RC slab bridge showed higher temperature dependency than the RC rahmen bridge owing to the presence of elastomeric bearings. Apart from the effect of temperature, non-negligible modal changes caused by other environmental factors were also identified. The results of this study are expected to provide valuable data for the health evaluation of bridges.

Robust optical displacement measurement of bridge structures in complex environments

A robust optical displacement measurement method is proposed herein for long-span bridges by considering complex environmental interference, such as illumination changes, system disturbances, and remote calibrations. First, to reduce the centroid shifts caused by lighting changes from the ambient or target itself, a center detection algorithm with an area-consistency constraint was applied. Optimized algorithm can reduce the noise variance by about half in the static laboratory experiment, which shows better illumination robustness than the adaptive threshold-based method. Second, to overcome the lower accuracy of 6-D camera pose tracking in remote measurements and limited correction effects of the widely used relative displacement method, a novel correction method with better implementability as well as accuracy was proposed for typical environmental vibrations. Third, an integrated real-time standing optical displacement sensor was developed for outdoor tests. In particular, a system combining a kilometer-level rangefinder and high-power laser designator was designed to achieve fast and fine object distance calibrations. Finally, the proposed method was applied to a short-span concrete bridge and a long-span steel bridge. The extracted displacement time histories at multiple points and deflection shapes at certain moments are expected to provide rich data for further performance evaluations.

Evaluating OMA System Identification Techniques for Drive-by Health Monitoring on Short Span Bridges

Evaluating OMA System Identification Techniques for Drive-by Health Monitoring on Short Span Bridges

MINIMALLY INVASIVE TECHNIQUE FOR ANTERIOR TEETH REPLACEMENT- CASE SERIES

Patients are very much concerned nowadays about the replacement of their missing teeth. Missing anterior teeth are a serious concern for patients, be it an aesthetic concern or functional loss. Aesthetics is the harmony between the teeth and the entire stomatognathic system. Aesthetic is the art that the dentist must procure, with a subtle touch of artistry, appreciation, and scientific knowledge, touch to recreate the beauty of a smile that suits the face and the personality of an individual. Beauty is in the eye of the beholder hence beauty is perspective. Science and dental treatment have progressed over the years, bringing us various options from removable partial dentures to fixed partial dentures and implants. Treatment options are delineated based on the patients concern as well as anatomic, functional, and scientific norms. Every treatment being fixed or removable has its own merits and demerits. An appropriate treatment plan should look into not only the aesthetic needs of the patient but also try to restore and maintain the harmony of the entire orofacial complex. Anterior teeth replacement can be done using a short-span cantilever bridge, as it is conservative and has a significant survival rate. Conventional cantilever fixed partial dentures have a survival rate of 82% over 10 years [1]. Maryland bridge is amongst other options which necessitate minimal tooth reduction with optimum bonding using adhesive cement.

Structural Behaviour of Metakaolin Geopolymer Concrete Wall-Type Abutments with Connected Wing Walls

This study work is related to exploring the role of connected wing walls in changing the behaviour of a metakaolin geopolymer wall type abutment when acted upon by all the forces that are generally applied on a short-span bridge. The modelling of abutment with connected wing walls is done using the STAAD Pro V8i SS6 software and all the loading applied for the analysis as per IRC: 6-2016. The modelling is done using the 4-noded plate elements for all the members, and the plate elements here are meshed using the quadrilateral meshing feature. The behaviour of the metakaolin geopolymer wall-type abutment is analyzed using various models with changing the basic parameters such as length of the wing walls, height of the walls, number of lanes on the bridge, and type of live load on the bridge. The various results are obtained in the form of bending moments from all the cases, which show us some really interesting behaviour of the abutment wall and the wing walls. As the length of the wing walls is increased, they take up more horizontal moments than the abutment wall and the deflection behaviour of the wing walls is way different than that of cantilever wall, and hence, it shows that the design aspects of the wing walls need to be checked. Also, the connected wing walls cause horizontal moments in the middle of the abutment wall, which is an interesting result; as now, it proves that after casting wing walls monolithically to the abutment wall, the design of the abutment wall cannot be done as cantilever wall, and we need to take care of this horizontal moment by providing required reinforcement. Also, as the length of the wing walls is short, the torsional moments become critical.

Fragility Analysis of RC Bridges Considering Spatially Varying Ground Motions and SSI

Long-span structures like bridges experience different movements at the supports because of the wave-passage, incoherence, and site-response effects. In this study, spatially varying ground motions were used to evaluate the seismic vulnerability of different RC bridges. To gain the goal, three prototypes of Caltrans reinforced concrete curve bridges with different column heights and various radii were selected and used for the numerical study. The spatially correlated ground motions were generated by the conditional simulation method and then converted to corresponding displacements time histories to perform non-uniform excitations. The structures were analyzed under generated series and the fragility curves were developed based on the defined limit states. Furthermore, soil-structure interactions and different soil conditions were included in evaluating the non-linear behavior of the bridges. The results show that the damage exceedance probability increased under non-uniform excitations and it is more obvious for long-span bridges. Also, it is found that the effect of soil-structure interactions on the probability of failure of short-span bridges is negligible but for long-span bridges, the effect is significant. Moreover, it is obvious that for long-span structures situated on soft deposits, a combination of spatially varying ground motions in conjunction with soil-structure inter-actions remarkably increases the responses.

Unified method for fully automated modal identification and tracking with consideration of sensor deployment

Automated modal identification and tracking provides the key technique for modal parameters based structural condition evaluation. However, the existing automated modal identification and tracking methods have limitations for situation with very few sensors deployed and require manual intervention. This paper proposes a unified fully automated modal identification and tracking method that can be used for structures with many or very few sensors deployed, for closely spaced modes with severe spatial aliasing and for structures with high flexibility or rigidity. A new index, which is called Modified Modal Observability Correlation, is proposed to estimate the similarity of two modes. New spurious mode elimination method and fully automated mode separation and tracking methods are proposed to realize the automated modal identification and tracking. The feasibility and novelty of the proposed method are validated using in-field monitoring data from a long span suspension bridge with high flexibility and a short span bridge with high rigidity and closely spaced modes. Automated modal identification and tracking for situations with many and very few sensors deployed for the two bridges are conducted, and extreme situation of closely spaced modes with spatial aliasing in mode shape is also considered to prove the novelty of the proposed method. Comparisons with existing mainstream methods are also conducted. The results show that the proposed method yields the right identification and tracking results in all situations, showing novelty in automated modal identification and tracking for structures with closely spaced modes having severe spatial aliasing when only very few sensors are deployed.

Multilayer bamboo composite hollow-core: Lab-scale and non-destructive testing of full-scale concrete bridges considering transverse bamboo pole as shear reinforcement

Due to bamboo's superior mechanical qualities, it has been often used in rural construction, however research on bamboo poles as structural reinforcement has been fairly limited. The purpose of this paper is to introduce a novel composite system made of several layers of bamboo hollow-core, named Mulbamcomphol concrete system for simplicity. On that premise, this paper analyzes the implementation of a composite slab system on a short span bridge consisting of concrete and multilayer bamboo arranged in a cross-section, without any utilization of steel reinforcement. Mulbamcomphol is so termed because to the presence of entire bamboo in this composite system (multilayer cross-ply bamboo composite hollow-core). Non-destructive testing will be utilized to analyze the flexural behavior of a full-scale vehicle under an actual service load. Due to the difficulties of obtaining exact results and the potential for bias, the study is conducted using a FEM-based model (thick shell and solid element). Bamboo slabs with a weak axis can sustain less stress than regular slabs, but they deflect by 81% less when subjected to the same 21 kN force. Simultaneously, when tested on a rigid axis, multilayer bamboo pole slabs can withstand a force 52 % more than conventional slabs at the same concrete volume, resulting in a 73 % reduction in deflection. Bridges constructed using Mulbamcomphol cross-ply bamboo composite concrete slab systems, on the other hand, demonstrate higher resistance to flexural loads in terms of ductility and maximum load that can be carried in both analysis and experimental testing.

Dynamic amplification responses of short span bridges considering scour and debris impacts

During extreme flooding events, bridges could experience large lateral displacements or even collapse due to either strong hydraulic forces or the effects of large waterborne debris, such as tree branches. The effects of waterborne debris on the structural behaviors of bridges include temporary accumulated dams and direct debris impacts. The additional lateral hydraulic forces and the acceleration of bridge scouring process due to temporary accumulated dams were investigated by researchers. Several debris impact force models were proposed to determine the loading effects applied on bridges. However, very few studies were conducted on the dynamic responses of bridges during flooding events considering the effects of large wood debris (LWD) as a combination of additional lateral hydraulic forces, foundation scour, and direct debris impacts. Therefore, the present study performed numerical analyses for bridges subjected to foundation scour and LWD impacts corresponding to flooding events. Besides, the effects of foundation scour and LWD impacts on the dynamic responses were simplified for bridge design purposes. Firstly, various short-span bridges with possible foundation scour depths due to debris accumulation were numerically simulated to obtain dynamic characteristics. Then, the hydraulic forces applied on the bridges were updated considering an extra blocking area due to debris accumulation. The collision forces due to floating woody debris were also introduced into the vehicle-bridge coupling system. Finally, the dynamic amplification factors (DAFs) with and without considering the effects of debris impacts were calculated and compared. It was found that the DAFs increase 20% at the maximum due to the effects of debris impacts. A modified factor was proposed to consider the effects. The reaction forces with and without the effects were also calculated to investigate the effects on the risk of deck unseating. Introducing possible debris impacts during flooding events into the dynamic analyses of bridges brings a more realistic estimation for the safety of bridges. The DAFs of bridges can be further taken as a guide for the supplements of design codes. The updated reaction forces would help to guide the risk mitigation of deck unseating.

SUGGESTED GUIDELINES FOR DESIGN AND CONSTRUCTION OF SHORT—SPAN BRIDGE ABUTMENTS WITH REINFORCED EARTH SYSTEM

Construction of small bridges is one of the real challenges in road construction, because it has so many problems. The reinforced earth system (mechanically stabilized earth wall) using gabion can be suggested as better alternatives for foundation of short—span bridges, especially in the remote areas. The latest research was about to find the design of reinforced earth abutment on various heights of abutments and various lengths of bridge span on soft to very soft consistency cohesive soil. However, the results of this research were less representative because the field conditions can vary from very soft to stiff cohesive soil and very loose to dense non-cohesive soil. Therefore, further research for wide range of soil conditions was conducted. Based on internal and external stability analysis, known that the number of geotextile needed for MSE wall (reinforced earth structure) ranging from 2 to 5 layer per meter depth, depending on the grade and the depth placed of the reinforcement, while the length of geotextile needed ranging from 3.2 to 22.5 meter, depending on the bridge span, embankment height, and parameters of the soil. MSE Wall cannot be built on soft to very soft soil (Cu < 2.79 Ton/m 2 ) without soil improvement to be done in the first place. Based on circular failure analysis (overall stability), known that in cohesive soils with stiff consistency (Cu = 6 Ton/m 2 ) to very stiff (Cu = 12 Ton/m 2 ) and non-cohesive soils with dense consistency (ф = 38 0 ) to very dense (ф = 42 0 ) does not require additional reinforcement. While on other soil consistency, some need additional reinforcement ranging from 0 to 22 layer of geotextile and from 0 to 35 pieces of micropiles, depending on the bridge span, embankment height, and grade of the reinforcement. Number of gabion needed as a facing of MSE wall ranging from 5 to 8 pieces per 2-meter width of abutments, depending on the embankment height.

Design of River Galeh Bridge Temanggung Regency with Reinforced Concrete T-Beam Structure

The old bridge of Sungai Galeh is a short span bridge with a reinforced concrete beam superstructure and a masonry bottom structure. This bridge is planned to be replaced for renovation. The replacement Sungai Galeh bridge is planned with the upper structure using reinforced concrete T-beams and the lower structure using reinforced concrete cantilever abutments. The purpose of this paper is to re-plan the Sungai Galeh Bridge in order to provide services for traffic users safely and comfortably. From the analysis results, the dimensions of the reinforced concrete T-beam are 40 x 80 and the dimensions of the diaphragm are 25 x 45.

Pounding mitigation of a short-span cable-stayed bridge using a new hybrid passive control system

This paper investigates the effectiveness of a new hybrid passive control system on the seismic response of an existing steel cable-stayed bridge considering the pounding effect. The proposed hybrid passive control system comprises a seismic isolator and a metallic damper. The bridge is located in a high seismic zone and has suffered several damages including the earthquake-induced pounding damage during the 1988 earthquake. Thereby, the proposed hybrid passive control system was investigated for seismic retrofitting of the bridge to mitigate the seismic damages due to future earthquakes. The hybrid control system was placed at the bridge ends and the tower–deck connection. A detailed three-dimensional finite element model of the bridge was created and validated with the earlier experimental results. A comparative analysis was performed through a series of nonlinear dynamic time-history analyses on the bridge equipped with the proposed and other control systems. The results showed that the hybrid control system reduced the bridge’s longitudinal seismic displacement, mitigated the pounding of the bridge with abutments and improved the overall seismic performance of the bridge.

Nonlinear analysis of the ballast influence on the train-bridge resonance of a simply supported railway bridge

In the present work, the influence of the ballast-deck interface on the dynamic response of single ballasted track, simply supported high speed railway bridges is investigated. The ballasted track railway bridge is modelled by a composite Euler-Bernoulli beam with two layers connected between them through longitudinal springs and dampers representing the nonlinear friction behavior occurring at their interface. A constant moving load model termed (HSLM-A) is utilized to simulate the moving trains. The governing nonlinear transverse vibration equation of the system has been derived by using the Hamilton’s principle. By applying the Galerkin method and using the Differential Quadrature Method (DQM) and the Integral Quadrature Method (IQM), the time history of the studied beam is numerically solved by the Runge-Kutta scheme. Considering two railway bridges having different lengths, the obtained results have shown that the dynamics of the system is governed essentially by a Duffing like oscillator, where the ballast superstructure contributes through both additional nonlinear stiffness and damping. The ballast-bridge interface was found to affect largely the dynamic response at resonance of short-span bridge than that of lengthier structures. In this last case the ballast influence can be reduced to just an additional mass.

Assessment of the Environmental Impacts of Bridge Designs Involving UHPFRC

Ultra-High-Performance Fibre-Reinforced Cementitious Composite (UHPFRC) has been developed to design lightweight structures and enhance existing designs. As the environmental footprint of the construction industry must be significantly reduced, the potential to lower environmental impacts of structures using UHPFRC needs to be explored. While the greenhouse gas emissions of a volume of UHPFRC are higher than that of the same volume of concrete, UHPFRC enables the reduction in the amount of material required in structural designs and improves the durability of structures. The environmental impacts of structural designs must thus be compared on the cradle-to-grave use cycle of the design at a project scale. In this study, a methodology is proposed to evaluate the ecological burdens of several bridge designs involving various structural elements in UHPFRC. The method proposes an analysis over three time horizons: first, the construction phase, then including the scheduled maintenance, and finally, adding the elimination. A case study of a short-span bridge in Switzerland is used to assess three alternatives of bridge designs: a conventional reinforced-concrete structure, a composite timber–UHPFRC bridge, and a full-UHPFRC solution. The results show that timber–UHPFRC structures can significantly reduce the environmental impacts of bridge designs, showing promising results in terms of sustainable development. The use of the methodology supports bridge owners in assessing the environmental impacts of structural designs.

A direct method to detect and localise damage using longitudinal data of ends-of-span rotations under live traffic loading

Existing work on rotation-based bridge monitoring has focused on indirect methods, such as bridge weigh-in-motion or influence line approaches. However, these approaches require increased instrumentation complexity, and require calibration, necessitating bridge closures. In this paper, we explore the potential of using rotation measurements to create a more practical and cost-effective monitoring system. To this end, we present a damage detection method which directly analyses bridge rotation data measured under live, free-flow traffic loading. We show how the Earth Mover’s Distance, typically used in statistics and image processing, can be applied directly on end-of-span rotation measurement data to achieve effective damage detection and localisation. Numerical simulation results demonstrate the approach’s robustness to the confounding effects of temperature variation and traffic diversity (vehicle type, loading, and velocity). The direct rotation measurement approach is applied to data from an in-service short-span bridge to demonstrate the technique’s capability with free-flow traffic loading.

Push-Out Test and FEM Analysis of Continuous Shear Connector

Composite steel concrete bridges with embedded continuous shear connectors are one of the newer popular options for short span (up to 20 m) bridges. They can be used for both road and railway bridges and due to their low structural height, nowadays, they are also a welcome alternative for bridge reconstructions – the concrete part serves as the bridge deck as well as the main structure. Unfortunately, In the Slovak Republic, no such bridges have been built as of yet (2020). At Technical University of Kosice, Department of Steel and Timber Structures, an extensive research regarding the steel shear connectors have been launched. Its goals are to bring new, easier for construction (due to prefabrication process), more resistant with even lower structural height, and more economical (due to lesser usage of materials and quick construction) geometrical solutions for composite steel concrete bridges as well as to open and popularize this solution for developers in the Slovak Republic. In this article, one of the new types is presented. It has a cross-section in a shape of a trapezoid, with holes in all its sides, except the bottom flange. Their purpose is to create concrete studs and secure full shear transmission with higher shear resistance, but they also serve to create space for transverse reinforcing bars. Its geometrical and material characteristics are closely specified. Results and process of push-out tests performed in Laboratory of Excellent Research onto three specimens are described and compared to results of finite element analysis simulation performed in Abaqus software.

Investigation of Indian standard plans issued by Ministry of Surface Transport for T-beam bridges

Bridges are the essential parts of the transportation facilities and are subjected to various forces depending on the onsite conditions and specific location of the bridge. T-beam bridges are pivotal in commuting from one place to other especially in shorter spans. The major forces acting on the T-beam bridges are static load, moving load and seismic load. Design of the T-beam bridges is conventional and versatile, as the main components are beams and slabs.There are various methods for the design of RC bridges, depending on the safety and serviceability. The earlier bridges were designed based on the working stress method as safety was the only criteria. Nowadays, the design is based on safety and serviceability. Most of the short span bridges in India are constructed as per the design details of standard plans by Ministry of Surface transport, Govt. of India. The complete design details for RCC slab and T-beam bridges (volume II) are available for the span ranging from 10 m to 24 m. The design details are established on the basis of working stress method as per code IRC 21: 1987. Provisions of IRC-6:1985 for seismic loading has also been incorporated in the design details. At present, working stress method of design of RC Road bridges has been outdated and IRC 112: 2011 code is in use.The study is about, to check the suitability of standard design drawings for spans varying from 10 m to 24 m based on limit state guidelines. design details are checked for the suitability at all seismic zones. MIDAS Civil (2019) software has been adopted to conduct this study. Comparative study has been made for the suitability of the design details of all spans in all seismic zones as per the new code.

Efficient second-order nonlinear finite-element simulation of concrete-filled FRP tubular arches

Concrete-filled fiber-reinforced polymer (FRP) tubes (CFFTs) are attractive as beams and arches in harsh environments due to their durability and ease of erection. A successful infrastructure application is the use of multiple, buried CFFT arches in short-span bridges. To effectively analyze and design CFFT arches under complex loadings, there is a need for numerical procedures that capture the structural behavior of CFFT arches including the effects of FRP confinement on the concrete core and second-order response. Here, a computationally efficient structural finite-element analysis technique for the second-order inelastic behavior of these CFFT arches is detailed. A curved, flexibility-based, layered-frame element is employed to handle geometric and material nonlinearities. A concrete constitutive model that explicitly considers the effect of dilation of the concrete core and confinement provided by the FRP tube is implemented. A bending test was performed on a CFFT arch, and experimental data compared with model predictions. Additional comparisons are made with CFFT arch and beam bending tests available in the literature. The model is shown to accurately predict the load-carrying capacity and ductility of CFFT members, and to capture arch collapse mechanisms arising from FRP rupture and concrete crushing.