Bridge Elements Research Articles

In Situ Evaluation of CFRP Strengthening for Corrosion-Deteriorated Bridge Bent Caps

Abstract Deterioration of various elements of aging concrete highway bridges is a common and serious concern. The deterioration can be due to embedded rebar corrosion and associated concrete spalli...

Improving the conversion accuracy between bridge element conditions and NBI ratings using deep convolutional neural networks

Interest in the analysis of bridge element conditions in the U.S. has increased lately. Since 2014, the Federal Highway Administration is publishing bridge element data to better predict the performance of bridges for improving the allocation of management resources. However, because bridge elements data are still limited, bridge engineers often rely on National Bridge Inventory (NBI) condition ratings to predict the performance of bridges, which have been assembled since the 1970s. Therefore, it is valuable to investigate the correlation that exists between NBI ratings and element conditions to improve our knowledge of the latter. The objective of this article is to perform the analysis of both bridge element condition data and NBI ratings to back-map NBI deterioration curves into element deterioration profiles using deep convolutional neural networks. The proposed approach better estimates NBI ratings from bridge element conditions by at least 24.8% when compared to other techniques. By using an error tolerance of ±1 on the NBI ratings, the proposed procedure can accurately predict more than 90.0% of the ratings, while element deterioration rates have a 60% probability of being predicted within the range of the empirical rates.

Real Time Bridge Dynamic Response: Bridge Condition Assessment and Early Warning System

Present study investigating the use of wireless sensor networks (WSNs) in the assessment of bridge condition as well as early warning system. The WSNs are used to measure the acceleration occurred on the bridge and the mode shape of the bridge as the excitation loads passing through the bridge. Fast Fourier Transform (FFT) is applied to transform the measured acceleration to get the frequency of the bridge dynamic response. Numerical integration is applied to determined the acceleration to get the displacement of the bridge dynamic response. Implementing structural dynamics equation, the effective stiffness of the bridge can be determined using the frequency. The effective stiffness and the bridge dynamic response are then used to obtained the bridge condition and load ratings. A scaled model of steel truss bridge and miniature truck with various loads were used to simulate the use of WSNs in bridge assessment, which were also used to validate the finite element model. The finite element model was then used to simulate various scenarios, including the scenarios in which the bridge elements had various level of damages. The behaviors of bridge with various level of damages can be used to identify the location and the level of damages in the bridge and were found to be useful as early warning system for bridges condition and load ratings.

Seismic Performances of Different Spandrel Wall Strengthening Techniques in Masonry Arch Bridges

ABSTRACT The majority of historical masonry bridges were constructed early years and they were not originally designed to carry the extent of loads imposed on them by current vehicular traffic and seismic loads. Therefore, many existing masonry arch bridges can need reassessment and upgrading. In addition to arch elements, the most vulnerable structural elements of masonry arch bridges under transverse seismic loads are the spandrel walls. Spandrel wall failures are local failures, however they affect the serviceability of the bridge considerably. The present paper aims to determine transverse nonlinear seismic performances of the spandrel walls of masonry arch bridges strengthened with different techniques, which are i) take down and rebuilt with tapered section instead of straight section, ii) using transverse tie bars, and iii) covering with a Fabric Reinforced Cementitious Matrix (FRCM) composite. The concrete Damage Plasticity (CDP) material model adjusted to masonry structures for the masonry units, Mohr–Coulomb material model for the backfill, and interface interactions between the backfill, spandrel walls, arch and FRCM units are considered in the 3D finite element model of the bridge. Modal, nonlinear static and seismic responses of the spandrel walls strengthened with the above three different techniques are determined using the finite element method, and the results obtained from the unstrengthened and strengthened models are evaluated and compared with each other. Some recommendations are presented for the strengthening of the spandrel walls in masonry arch bridges.

Galloping performance of various shape of bridge hanger

Long span bridge and slender element of the bridge is sensible to dynamic wind action such as flutter buffeting, vortex induced vibration and galloping. For arch bridge, vibration of hanger due to dynamic action of the bridge has been experienced including hanger vibration of Tayan Bridge. The possible phenomena of the vibration are flutter, galloping and vortex induced vibration. This paper presenting the study of galloping phenomenal on the hanger of the Tayan Bridge. Several shape of the bridge hanger has been considered in this study. Computation Fluid Dynamic has been used to determine the static wind coefficient of the hanger. Glauert-Hartog Criteria has been applied to examine the performance of the bridge hanger to galloping. The result showed that that only circle shape that is not experiencing galloping

Quality of Element-Level Bridge Inspection Data

Bridge inspection results provide input for several important functions such as maintenance, repair, and rehabilitation, bridge load capacity ratings, truck load routing/permitting, and future safety/condition predictions. As a result, the quality and reliability of inspection data are important for bridge management and to ensure the safety and serviceability of bridges. Element-level data collection has been required nationwide for bridges on the National Highway System since 2014, and therefore is relatively new to some bridge owners. The objective of the research reported here was to assess the quality of element-level bridge inspection data by comparing bridge inspection results between different bridge inspectors assessing the same bridges. This paper reports results from two research studies completed to collect data on the quality (i.e., variability) of element-level inspection data. Results of field trials indicated that there was significant variability in the data for bridge elements reported in the study. Based on these data, the element-level inspection results were widely dispersed—the smallest coefficient of variation calculated from the current studies was 18%, but typical values were found to be greater than 50% in most cases, and often greater than 100%. These data provide examples from a series of field trials that illustrate the need for improving the quality of element-level inspections to ensure the reliability of the data provided.

Co-Active Prioritization by Means of Contingency Tables for Analyzing Element-level Bridge Inspection Results and Optimizing Returns

An efficient prioritization of bridge actions such as preventive maintenance, rehabilitation, or replacement (MRR) that accounts for inter-element interactions will optimize a long-term return on investments (ROI) in terms of service life extension. What enables this return is the assignment of “Co-Active” elements. This study develops a methodology based on the concept of “Co-Active elements”. The word, “Co-Active”, is used to represent a small group of elements that act together to improve the Bridge Health Index (BHI). The Co-Active parameters for three major bridge groups in Georgia are presented. To illustrate how the Co-Active model works, 1439 in-service bridges’ Element-Level Bridge Inspection results from the state of Georgia in U.S.A., representing a concrete bridge group with six Co-Active elements, are studied. The analysis results indicate that the overall BHI improves by 20% over the subsequent 20 years when expansion joints are replaced. The effects of Co-Active elements on the BHI predictions are quantifiable and depend on factors such as the timing of MRR, the condition of bridge elements as well as the type of MRR. Furthermore, it is concluded that inter-dependent relationships among Co-Active elements are highly affected by Co-Active coefficients. They increase when the degree of dependency among elements increases. Finally, the proposed bridge Co-Active prioritization analysis accounts for a performance target and associated gaps and thus is able to identify critical elements that affect bridge service life the most.

Thermal stress analysis by finite elements of a metal-ceramic dental bridge during the cooling phase of a glaze treatment

In the present paper, a computational finite element analysis (FEA) was developed by using the COMSOL Multiphysics® software to evaluate the thermal accumulated stress on a 3-unit dental ceramic pressed over metal (POM) bridge, at different cooling rates during the glaze treatment. The cooling rates are related to the free opening of the furnace at 800 °C (extreme case) and the restricted opening when the restoration reaches 450 °C (slow case). The thermal expansion coefficients of the materials and the glass transition point of the ceramic were measured experimentally using a dilatometer test. The FEA was performed based on the ceramic temperature profile, which was determined experimentally by using thermocouples type K. When the dental ceramic reaches its transition temperature (Tg) at 510 °C, maximum principal stress at the grooves from the occlusal surface of the pontic are reported as 140 MPa for the slow and 400 MPa for the fast cooling rate. Additionally, it is demonstrated that stresses can be reduced by using low Young's modulus metals and with small differences in the material's thermal expansion coefficient (CTE).

Comparison of fatigue crack propagation behaviour in two steel grades S235, S355 and a steel from old crane way

Utilization of various steel grades in civil engineering allows designing bridges, bridge elements or simple structures according to their fracture mechanical properties. The service intervals of structures, which are going to be in use for a long time, cannot be calculated only on the basis of tensile and brittle fracture properties but also on the knowledge of the resistance to the fatigue crack growth. This contribution presents a comparison of the fatigue behaviour of two modern steel grades S235 J2, S355 J2 and a steel extracted from an old crane way. The comparison of these steel grades is done by fatigue crack propagation tests (the results of the experimental tests are described using concept of the stress intensity factor range ΔK). The fatigue properties are discussed and recommendations for the use of the steels are stated.

The performance of composite steel in the elements of a post-fire steel bridge

The steel structure is commonly acknowledged able to return to its original strength condition. It is yet unknown whether composite structure may return to its initial condition. Test specimen on the present study consists of 8 units, each of them divided into four stud-connector bold (SP) composites beams and four UNP connector (SF) composite beams. Each of the specimen has control value by SP/020 and SF/020, and other six specimens with combustion of SP/400, SP/550, SP/700 and SF/400, SF/500, SF/700, within condition of point load for about 12 kN. The study intends to investigate composite girder of post-fire bridge element towards duration and heat temperature factors and effect of beam performance towards stud-connector and UNP connector composites. The results draw several conclusions; The process of composite combustion shows that the failure on composite steel beam specimen is due to the load, burning duration and temperature which results in residual deflection. Deflection test reveals the effect of temperature, load, and duration do not give significant impact to load capacity of post-combustion beam structure.

Optimization of cables size and prestressing force for a single pylon cable-stayed bridge with Jaya algorithm

In recent years, due to the many advantages cable-stayed bridges have often constructed in medium and long span. These advantages can be listed as an aesthetically pleasing appearance, economic and easy construction, etc. The main structural elements of cable-stayed bridges are listed as deck, pylon, cables and foundation. Perhaps one of the most vital and expensive of these structural elements is stay-cables. Stay-cables ensure the allowable displacement and distribution of bending moments along the bridge deck with prestressing force. Therefore the optimum design of the stay-cables and prestressing force are very important in achieving the performance expected from the cable-stayed bridges. This paper aims to obtain the stay-cables size and prestressing force optimization of the cable-stayed bridge. For this purpose, single pylon and fan type cable configuration Manavgat Cable-Stayed Bridge was selected as an example. The three dimensional (3D) finite element model (FEM) of the bridge was created with SAP2000. Analysis of the 3D FEM of the bridge was conducted under the different combined effects of the self-weight of the structural element, prestressing force of stay-cable and live load. Stay-cable stress and deck displacement were taken into account as constraints for the optimization problem. To optimize this existing bridge a metaheuristic algorithm named Jaya was used in the optimization process. 3D FEM of the selected bridge was repeatedly analyzed by using Open Applicable Programming Interface (OAPI) properties of SAP2000. To carry out the optimization process the developed program which integrates the Jaya algorithm and the required codes for calling SAP2000 is coded in MATLAB. At the end of the study, the total weight of the stay-cables was reduced more than 40% according to existing stay cables under loads taken into account.

Predicting Bridge Elements Deterioration, using Collaborative Gaussian Process Regression

Roadway and railway bridges are not only integral, but also vulnerable parts of terrestrial transport networks. Structural failures of bridges may lead to disastrous consequences on users and society at large. Bridge predictive deterioration models are extremely important for effective maintenance decision-making. However, the lack of enough inspection data between maintenance activities of a bridge complicates the development of accurate predictive models. Presented herein is a Gaussian Process Regression (GPR) based collaborative model for predicting the condition of bridge elements with limited available inspection data per bridge. This model has been applied in 137 bridge decks, showing that collaborative prognosis has the potential to predict the condition of different types of bridge elements, composing different types of bridges.

Problem of the degradation criteria for transportation construction elements

The article is devoted to the pressing problem of managing the reliability and durability of transport constructions. Modern scientific approaches to assessing the technical condition of transport facilities based on an analysis of element degradation during the life cycle of operation considered. The article presents the advantages and disadvantages of the most common prediction models of the technical condition of building structures. Each model uses a characteristic criterion for degradation of building structures: load and unload cycles, rejection number of chlorides, intensity coefficient, a geometric parameter (parameters) of the crack in the material, reliability, etc. The problem of choosing the control parameter of the lifecycle model of the bridge elements is analyzed. The theoretical basis for the Markov phenomenological model of damage accumulation and the model of degradation based on the physical and mechanical characteristics of the material formulated. Depending on the stage of the life cycle, it is proposed to select the type of prediction model.

Results of the checking calculation of the structures of pedestrian bridge over the military descent in Odessa

Problem. The highest pedestrian bridge in Odessa is stretched over the Military Descent between Primorsky Boulevard and M. Zhvanetsky Boulevard in Odessa. During the whole life of pedestrian bridge, the research and testing [3] of bridge structure in 1969, and inspection [6] in 2000 and 2005 were carried out. Unfortunately, not all recommendations of the work [6] have been implemented. This fact doesn’t contribute to the satisfactory operation of pedestrian bridge structure, especially near the shore anchor No. 0. The above-mentioned recommendations included: vertical planning of the slope and the area under the bridge deflection near the shore anchors; fixing a block-divided limestone-shell rock massif; fixing the retaining walls, which support the slope, in the area of inclined supports foundations and near the shore anchors No. 0 and No. 3. The technical condition of the bridge is generally classified as partially serviceable (state 4) according to standard [9]. According to inspections [3], the operating conditions of the bridge structure and the surrounding area are extremely unsatisfactory. Goal. The goal of the work is estimating the technical condition of pedestrian bridge structure over the Military Descent between Primorsky Boulevard and M. Zhvanetsky Boulevard in Odessa, to ensure the further reliable operation of the pedestrian bridge and development of the project of high-priority measures for bridge major overhaul. Methodology. On the basis of provided materials, a three-dimensional computer model of pedestrian bridge was developed. Computer model calculations were performed using the LIRA software package. The design scheme of the bridge is adopted in the form of a spatial system consisting of shell elements that simulate the behavior of steel sheet structures, as well as bar elements that simulate the behavior of struts on shore anchors, anchor bars and auxiliary elements in modeling the hinged support of inclined racks. Results. Analysis of the results of steel structures calculation showed that: the maximum load on foundation pier 1a from the design load combination (DLC) No. 6 is 289.1 t; the first and third oscillation modes are translational vertical oscillations, the second oscillation mode is horizontal oscillations; the maximum vertical deflection in the central span from DLC No. 16 is 193 mm, which exceeds the limit deflection of 130 mm; the vertical deflection in the end spans doesn’t exceed the limit value, which is 105 mm; the maximum horizontal deformation on the shore anchor No. 0 is 51.8 mm, and on the anchor No. 3 it is 23.6 mm; the natural oscillation periods of unloaded bridge are: for the 1st mode (vertical) – 0.892 s, for the 2nd mode (horizontal) – 0.576 s. They don’t fall into the forbidden range [10] – from 0.45 to 0.60 s in vertical plane and from 0.9 to 1.2 s in horizontal plane; the main stresses in the steel bridge structures from DLC No. 2, 3, 4, 6, 7, 9, 10, 12, 13, 15, 16, 28, 31 exceed the yield strength of steel. At the same time, the places of stress concentration and their distribution pattern are identical for all DLC, except DLC No. 3, where an excess of the yield strength of steel occurs in the lower zones of inclined racks and in the support tables of cantilever beams; stress concentrators in computational model, to some extent, can be caused by peculiarities of mathematical algorithm of finite element method, and assumptions that were adopted in computational model. Practical value. Making final decisions about strengthening the bridge structural elements in places of stress concentration, it is necessary to perform a duplicate calculation in another software package; if the result is confirmed, it is necessary to strengthen the bridge elements according to the specially developed project and consider reducing the load (mobile and pedestrian); to reduce the temperature load on the steel bridge structures, it is urgent to overhaul the moving rollers of shore anchors No. 0 and No. 3 in accordance with the project [4]; engineering and geodetic observations should be continued for vertical displacements of bridge elements and horizontal displacements of pedestrian part of the bridge.

Comparative Study of Data Mining Models for Prediction of Bridge Future Conditions

Highway and bridge agencies use several systematic inspection approaches to ensure an acceptable standard for their assets in terms of safety, convenience, and economic value. The Bridge Condition Index (BCI), used by the Ontario Ministry of Transportation, is defined as the weighted condition of all bridge elements to determine the rehabilitation priority for the bridge. Therefore, accurate forecasting of BCI is essential for bridge rehabilitation budgeting and planning. The large amount of data available about bridge conditions for several years enables the use of different mathematical models to predict future BCI. This research focuses on investigating different classification models developed to predict the BCI in the province of Ontario, Canada, based on the publicly available historical data for 2,802 bridges over a period of more than 10 years. Predictive models used in this study include k-nearest neighbors (k-NN), decision trees (DTs), linear regression (LR), artificial neural networks (ANN), and deep learning neural networks (DLN). These models are compared and statistically validated via cross validation and paired t-test. The decision tree model showed acceptable predictive results (within 0.25% mean relative error) when predicting the future BCI and is the recommended option based on its performance and certainty in posterior maintenance decision making for the selected case study.

Experimental evaluation of concrete-to-UHPC bond strength with correlation to surface roughness for repair application

Exposing bridge elements to severe environmental conditions causes a reduction in service life and durability which demands repair or total replacement. Different strategies for repair and retrofit can be chosen. These strategies include patching, crack repairs, concrete sealers, a protective layer made of concrete or steel. Ultra-high performance concrete offers an option for repairing and retrofitting different structural elements, however, the bond strength between concrete substrates and ultra-high performance concrete can still be considered a knowledge gap in the literature. In this paper, bond strength between ultra-high performance concrete and substrate made of normal concrete with different surface preparation was investigated experimentally. Thirty specimens were tested under bi-surface shear test with different surface preparation, including roughness degree, mechanical connector, and bonding agent. Furthermore, two non-contact test methods including terrestrial laser scanning and digital image processing were incorporated to evaluate the roughness of the substrate interface and correlate the roughness degree to the bond strength between the two materials. The results showed that an adequate roughness for the interfacial surface with or without mechanical connectors transferred the failure mode to the concrete substrate indicating high bond strength between the two materials if compared to interfacial surfaces without any preparat;ion. In addition, the use of bonding agent could harm the bond strength between the two material which is inappropriate for retrofitting. The result from scanning and image processing showed that both methods qualitatively identified the degree of interface roughness and their result can be correlated to bond strength.

Determination of the technical condition of the metal bridge with wood covering

At present, the age of most transport facilities in the Russian Federation estimated by many decades, and most require reconstruction or repair. Consequently, there is an urgent need for periodic surveys and monitoring of the condition of such facilities. The main goal of these measures is to maintain high rates of transport infrastructure efficiency, the achievement of which is impossible without examining, analyzing and evaluating parts of the structure in the aquatic environment, and, as a result, the occurrence and development of various defects and damage. The most important conditions for ensuring uninterrupted and safe traffic on the bridges of vehicles and pedestrians are the regulatory bearing capacity of the structure and cleaning of the roadway and sidewalks. Then compliance with traffic safety requirements on decks and observing the characteristics and maintaining the function of the bridge for the period of ice drift and flooding. Timely execution of works for the care, maintenance, and repair of bridge elements. Technically stable structures and their reliability can be ensured by observing all the parameters of the structure of the road category and the requirements of regulatory documents. The paper presents the materials of the inspection of the bridge after repair — defect classification by groups and hazard classes — the results of determining the carrying capacity of the survey materials given.

Accelerated bridge construction projects using high performance concrete

The National Bridge Inventory (NBI) of the United States includes more than 600,000 highway bridges. Approximately 25 % of the nation’s inventory is structurally deficient or functionally obsolete. Currently, the Federal Highway Administration (FHWA) is investigating different alternatives to build new bridge with longer life-span, lower maintenance, and repair needs.Currently, the FHWA is successfully using accelerated bridge construction (ABC) techniques to expedite the construction of new bridges, and minimize material, labor, and equipment cost. In this research, the ABC of new bridges using prefabricated bridge elements and systems (PBES) is discussed, including the fabrication of precast/prestressed elements using an economic high performance concrete (HPC) mix, developed using local construction materials. The successful use of HPC in fabricating PBES used in ABC techniques allows the FHWA to construct new bridges under current budget restraints. This improves the overall rating of the bridge network within the United States.

Damage detection and quantification in deck type arch bridges using vibration based methods and artificial neural networks

Vibration based methods can be used to detect damage in a structure as its vibration characteristics change with physical changes in the structure. Extensive research has been carried out on the use of such methods to detect damage in a number of simple and some complex structures. Arch bridge is a popular type of bridge with rather complex vibration characteristics which pose a challenge for using existing vibration based methods to detect damage in them. Further, its complex form of damage detection, even with modified vibration based methods makes the quantification process harder and challenging. This paper develops and applies a vibration based method especially suited for arch bridges to detect, locate and quantify damages in the structural components. In the proposed method, modified forms of the modal flexibility (MMF) and modal strain energy (MMSE) based damage indices coupled with the Artificial Neural Network (ANN) technology is used to provide an overall damage assessment. The procedure to detect and locate damage was experimentally validated and applied to a full scale long span arch bridge under a range of damage scenarios. Damage indices obtained from noise polluted vibration data are then used as input data for training and validation of the neural networks. Two neural networks were trained separately using MMF and MMSE damage indices and a network fusion approach is used to obtain unambiguous and accurate results for detecting, locating and quantifying damages. The trained neural network system was then successfully applied to identify unknown damages using only vibration data of damaged structural elements of arch bridges. The findings of this paper will contribute towards the safe and efficient operation of arch type bridges.

Spin valve based sensor elements for full Wheatstone bridge

Present work deals with methods for creating opposite pinning directions in micro-objects based on a spin valve by one thermomagnetic treatment. The methods are based on the thermomagnetic treatment in spin-flop state of synthetic antiferromagnet. We use splitting the magnetic structure in spin-flop state of synthetic antiferromagnet to form opposite pinning directions in different micro-objects by one thermomagnetic treatment. The positive characteristic (dR/dH) was obtained in the two sensor elements of the full Wheatstone bridge, and the negative characteristic (dR/dH) in the other two elements.