Prestressed Concrete Bridge Research Articles

Analysis of concrete T-girder using MIDAS

The concept of pre-stressed concrete appeared in the year 1888. In this present engineering technology, durable and sustainable bridges play an important role for the socio-economic development of the nation. Owners and designers have long recognized the low initial cost, low maintenance needs and long-life expectancy of pre-stressed concrete bridges. This is reflected in the increasing market share of pre-stressed concrete, which has grown from zero in 1950 to more than 55 percent today. This growth continues very rapidly, not only for bridges in the short span range, but also for long spans with excessive length which, here therefore, has been nearly the exclusive domain of structural steel. Many bridge designers are surprised to learn that precast, pre-stressed concrete bridges are usually lower in first cost than all other types of bridges coupled with savings in maintenance, precast bridges offer maximum economy. The precast pre-stressed bridge system has offered two principal advantages: it is economical and it provides minimum downtime for construction.

Long-Term Behavior of a Prestressed Concrete Bridge with Corrugated Steel Webs

Abstract Long-term performance is one of the less-studied cases of the prestressed concrete bridge with corrugated steel webs. In this study, the time-dependent behavior of a bridge of this type wa...

Experimental–theoretical investigation of the short-term vibration response of uncracked prestressed concrete members under long-age conditions

The short-term vibration response of uncracked prestressed concrete (PC) members under long-age conditions was investigated. No study has examined long-term phenomena of concrete, such as its tendon relaxation, creep, curing, and shrinkage, under the aforementioned conditions. Therefore, a research sub-program was initiated at the National Center for Research on Earthquake Engineering on the basis of an experimental campaign on uncracked PC bridge members initiated in 2015. In particular, a simply supported PC beam composed of a parabolic-bonded tendon and high-strength concrete made in Taiwan was allowed to short and, consequently, long-term prestressing losses measured for approximately 9.5 months. During short-term prestressing losses and after long-term prestressing losses, free short-term transverse vibrations were induced in the PC beam characterized by a second-order initial curvature and an axial end constraint. The time-dependent Young’s modulus of the beam was determined by conducting compression tests on cylinders during the short-term prestressing losses. Moreover, compression tests were conducted on cores drilled along the PC beam’s span after free vibration tests. The theoretical time-dependent Young’s modulus of the beam was evaluated according to the compression test results. The experimental data were compared with a reference Euler–Bernoulli solution and finite-element (FE) model that describe the dynamics of PC girders by considering the effective prestressing force. The fundamental frequencies of the PC beam were mainly sensitive to the variation in its initial tangent Young’s modulus due to the consolidation or hardening of concrete. These frequencies were unaffected by the second-order initial curvature. In conclusion, the reference solution and FE model can accurately predict the short-term dynamics of uncracked PC members exposed for long times.

Full-scale investigation of post-tensioned prestressed concrete bridge girders subjected to frost heaving in cold regions

Frost heaving is one of the major diseases of post-tensioned prestressed concrete structures in cold regions. This study investigates the effects and underlying mechanisms of frost heaving damages on the mechanical behaviors of full-scale post-tensioned prestressed concrete girders of a highway bridge. Forensic investigations were performed for three bridge girders through destructive tests, which included borehole, anatomy, and flexural tests, with an intact girder as the control. Three-dimensional nonlinear finite element models of the girders were established to understand the mechanisms of the effect of frost heaving. The results show that frost heaving reduced the effective prestress, mechanical properties of concrete, and bond between concrete and tendon, thus reducing the crack resistance and durability of the girders. This study provides new insights into post-tensioned prestressed concrete girders under frost heaving. The results are useful to improve the safety, serviceability, and durability of prestressed concrete bridges in cold regions.

Analysis of Pre-Stressed Box Girder Bridge under Different Standard Codes: A Comparative Study

Pre-stressed concrete bridge analysis is completely dependent on the standards and design criteria. Herein, the current study compares like a pre-stressed concrete bridge under the effect of two different loading standards and specifications. The two different loading standards considered herein are IRC 6: 2000 and AASHTO-LRFD standards. Further, the pre-stressed box girder bridge is modelled and analysis in MIDAS CIVIL. On carrying out analysis, the primary structural analysis parameters which are important for the design of structure, are studied. These parameters are shear force, bending moment and torsion in the bridge elements along its length. It became observed that AASHTO standards are uneconomical than IRC standards, due to consideration of heavy weight vehicle load moving on the bridge span. Thus, it might be said that pre-stressed box girder bridge analysis and design should be carried out effectively and optimistically using IRC standards and specifications.

Analysis of Shear Capacity of Prestressed Concrete Bridge Girders

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Effect of Skew Angles on Longitudinal Girder and Deck Slab of Prestressed Concrete T Beam Girder Bridges

Abstract: The present paper shows the effects of varying skew angles on pre-stressed concrete (PSC) bridges using finite elemental method. Studies are carried out on PSC bridge decks to understand the influence of skew angle and loading on behaviour of bridges. The results of skewed bridges are compared with straight bridges for IRC Class AA Tracked loading. Also, a comparative analysis of the response of skewed PSC Slab Bridge decks with that of equivalent straight bridge decks is made. The variation of maximum longitudinal bending moment (BM), maximum transverse moment, maximum torsional moment, and maximum longitudinal stresses deflection at obtuse corner, acute corner with skew angles are studied for bridge deck. It is found that Live load longitudinal bending moments decreases with an increase in skew angle, whereas a maximum transverse moment and maximum torsional moment increases with an increase in skew angle. The benefit of pre-stressing is reflected in considerable decrease in the longitudinal bending moment, transverse moment and longitudinal stresses. The models are analysed with the help of software CSI-Bridge V 20 Version. Keywords: Skew angle effect, Longitudinal moment, Transverse moment, CSI- Bridge software, Deck slab, Finite element method.

Statistical Inversion Approach for Stress Estimation Based on Strain Monitoring in Continuously Pre-Stressed Concrete Beams

Stress is one of the most important physical indexes reflecting the mechanical behavior of concrete structures. In general, stress in structures cannot be directly monitored and can only be estimated through an established model of stress and strain. The accuracy of the estimated stress depends on the rationality of the established model for stress and strain. As the strain measured by sensors contains creep, shrinkage, and elastic strain, it is difficult to establish an analytical model for strain and stress. In this paper, a statistical inverse method was utilized to estimate the stress in continuously pre-stressed concrete beams based on the monitored strain. Stress in the beams and the model uncertainty factors were treated as model parameters. A linear-simplified method was adopted to determine the prior distribution of the stresses. The posterior distribution of the stresses at different locations during bridge construction can be obtained by the proposed method. A continuously pre-stressed concrete beam bridge was taken as the case study to verify the effectiveness of the proposed method. Additionally, the constitution of the total strain in the different construction stages was calculated. It was concluded that the creep strain is the dominant part of the total strain.

Modification of Variance-Based Sensitivity Indices for Stochastic Evaluation of Monitoring Measures

In complex engineering models, various uncertain parameters affect the computational results. Most of them can only be estimated or assumed quite generally. In such a context, measurements are interesting to determine the most decisive parameters accurately. While measurements can reduce parameters’ variance, structural monitoring might improve general assumptions on distributions and their characteristics. The decision on variables being measured often relies on experts’ practical experience. This paper introduces a method to stochastically estimate the potential benefits of measurements by modified sensitivity indices. They extend the established variance-based sensitivity indices originally suggested by Sobol’. They do not quantify the importance of a variable but the importance of its variance reduction. The numerical computation is presented and exemplified on a reference structure, a 50-year-old pre-stressed concrete bridge in Germany, where the prediction of the fatigue lifetime of the pre-stressing steel is of concern. Sensitivity evaluation yields six important parameters (e.g., shape of the S–N curve, temperature loads, creep, and shrinkage). However, taking into account individual monitoring measures and suited measurements identified by the modified sensitivity indices, creep and shrinkage, temperature loads, and the residual pre-strain of the tendons turn out to be most efficient. They grant the highest gains of accuracy with respect to the lifetime prediction.

Seismic fragility assessment of Chilean skewed highway bridges

The 2010 Maule, Chile earthquake demonstrated that many bridges were highly vulnerable to seismic demands. Among these bridges, skewed multi-span prestressed concrete girder bridges supported on non-anchored elastomeric bearings were the most vulnerable ones. After the 2010 Maule earthquake, several damaged skewed bridges were repaired and retrofitted using an updated seismic design criterion. Therefore, this study aims to compare the seismic performance of typical Chilean skewed highway bridges in their original design (prior to 2010) and in their repaired condition (post 2010). With this aim, three-dimensional (3D) nonlinear finite element models of four skewed bridges, which were damaged during the 2010 Maule earthquake, are developed and analyzed. Nonlinear static and incremental dynamic analyses (IDAs) are conducted, and fragility curves are obtained to evaluate the short-term evolution of the Chilean design practices. Additionally, the influence of the skew angle, vertical seismic bars, modelling assumptions and anchorage of elastomeric bearings, on the seismic performance of Chilean skewed highway bridges is analyzed through IDAs and fragility curves. The results of this study show that repair measures considered after the 2010 Maule earthquake improve the seismic performance of skewed bridges and effectively prevent span unseating. However, the adopted measures do not significantly improve the performance at slight to moderate damage states. It is also demonstrated that the skew angle and deck-abutment pounding have significant influence on the seismic performance. Finally, the results show that an adequate modelling of vertical elements, such as elastomeric bearings, must be considered to avoid underestimating displacement demands.

Development of heavy truck models and their effects on girder bridges

The traffic on highway bridges has been increasing in both volume and magnitude, which even has become one of the main reasons leading to damages and collapse of bridges. Most of the existing regulations for overloading checking are carried out based on various limits of gross vehicle weights and axle loads. However, the results of relevant researches show that weight is only a potential factor but not the dominating factor in threatening the safety of bridges. In this study, the concept of load-effect-based heavy truck is proposed for overloading checking, and then three years of WIM data were collected and used to develop heavy truck models for each truck type, based on the understanding of the characteristics and configurations of heavy trucks as well as the distribution of their main parameters. Furthermore, the typical heavy truck models selected and their possible combinations are applied to a simply supported pre-stressed concrete T-beam bridge model with three loading levels, considering one-lane, two-lane and three-lane loaded respectively, then the induced load effect, deflection and stress are discussed for 20 loading cases. The results show the bending moment caused by heavy trucks moving on multiple lanes is 1.6 times the value of the standard truck model in Chinese specification, and the eccentric loading due to a very heavy vehicle moving on single lane usually lead to more severe effect.

FORENSIC ANALYSIS OF THE WUXI 312 VIADUCT OVERTURNING COLLAPSE

On October 10, 2019, a three-span concrete continuous box girder on National Highway 312 in Xishan District, Wuxi City, overturned under the action of two vehicles. Investigated the accident site first, then established a geometrically nonlinear finite element model based on wreckage photos and construction drawings, and studied the overturning mechanism. An overload determination method based on the strength and overturning stability effects is proposed. The results include: the overturning test results based on the standard lane load demonstrate that the bridge does not meet the overturning test requirements specified in the Specification for Design of Highway Reinforced Concrete and Prestressed Concrete Bridge and Culvert (2018 edition); the superstructure under the action of the overloaded vehicle first rotated, then slid, and finally exhibited a combination of substantial rotation and sliding overturning mode; the superstructure has a certain safety margin between bearing separation and overturning; the calculation based on the strength and overturning stability effect proves that the overturning effect generated by the overloaded vehicle is greater than the overturning capacity of the structure, indicating that the overturning is mainly attributed to the overload. However, the structural bending capacity turns out to be sufficient through further calculation, indicating that the overturning damage occurred earlier than the occurrence of strength damage, and that the overturning resistance and bending resistance do not match.

Evaluating in-service structural behaviour of an operational railway bridge using fibre optic sensing and structural model updating

Multi-girder prestressed concrete bridges are a very common structural form for bridges around the world. Their continued use is expected in the future given the advantages these structures have with respect to speed of construction, reduced maintenance and improved material efficiency. However, the in-service behaviour of these types of structures, such as their load distribution characteristics, support boundary conditions and the contribution of secondary elements, is still not well understood, and few studies have investigated these areas in depth. Gaining better insight into these aspects of bridge behaviour will enable more realistic structural assessment and thus facilitate more targeted maintenance and refurbishment of these bridges. This paper evaluates the in-service structural behaviour of an operational prestressed concrete railway bridge, which has been monitored using a dense network of fibre optic strain and temperature sensors since it was constructed in 2015. In particular, the normalised curvature profiles and the neutral axis positions across the composite solid slab bridge deck may be used to extract information about the bridge’s transverse load distribution behaviour, support boundary conditions and the stiffness contribution of secondary elements. Using this information, structural model validation and updating were performed with the goal of providing a more realistic assessment of structural behaviour and structural capacity. The proposed methodology and workflow in this study provide new insights into the real performance of multi-girder prestressed concrete bridges and thus can be used to improve their operation, maintenance, assessment and refurbishment.

Effect of temperature loading on the performance of a prestressed concrete bridge in Oklahoma: Probabilistic modelling

Spatial and temporal temperature variations in bridge structures due to changes in the surrounding climate cause bridge expansion which, if restrained, may induce secondary stresses in structures. Temperature effects have always been considered to be one of the most critical issues in the performance of traditional Prestressed Concrete (PC) bridges. In order to (1) develop an efficient temperature loading model for predicting bridge temperature-induced response; and (2) develop guidelines addressing the effects of temperature loading in reliability-based condition evaluation, numerical and analytical studies were conducted on a PC girder bridge in Oklahoma, USA. This paper focuses on the probabilistic modelling of temperature loading. Firstly, a heat transfer model was established using hourly input climate data to estimate the temperature distribution, and compared with monitoring counterparts for calibration. Secondly, the validated analytical model was employed to investigate the effects of thermal properties of concrete by a parametric analysis; Based on extreme environmental conditions from the 20-year climatic data and analytical results, probabilistic models of uniformly distributed temperature fields and temperature gradients were proposed, and the temperature loading value with a 75-year return period was determined and compared with recommended value in the AASHTO LRFD. The proposed temperature loading model can aid engineers in predicting the thermal behavior of PC bridges in Oklahoma, USA.

A Combined Experimental-Numerical Framework for Assessing the Load-Bearing Capacity of Existing PC Bridge Decks Accounting for Corrosion of Prestressing Strands.

Bridges constitute important elements of the transportation network. A vast part of the Italian existing infrastructural system dates to around 60 years ago, which implies that the related bridge structures were constructed according to past design guidelines and underwent a probable state of material deterioration (e.g., steel corrosion, concrete degradation), especially in those cases in which proper maintenance plans have not been periodically performed over the structural lifetime. Consequently, elaborating rapid yet effective safety assessment strategies for existing bridge structures represents a topical research line. This contribution presents a systematic experimental-numerical approach for assessing the load-bearing capacity of existing prestressed concrete (PC) bridge decks. This methodology is applied to the Longano PC viaduct (southern Italy) as a case study. Initially, natural frequencies and mode shapes of the bridge deck are experimentally identified from vibration data collected in situ through Operational Modal Analysis (OMA), based on which a numerical finite element (FE) model is developed and calibrated. In situ static load tests are then carried out to investigate the static deflections under maximum allowed serviceability loads, which are compared to values provided by the FE model for further validation. Since prestressing strands appear corroded in some portions of the main girders, numerical static nonlinear analysis with a concentrated plasticity approach is finally conducted to quantify the effects of various corrosion scenarios on the resulting load-bearing capacity of the bridge at ultimate limit states. The proposed methodology, encompassing both serviceability and ultimate conditions, can be used to identify critical parts of a large infrastructure network prior to performing widespread and expensive material test campaigns, to gain preliminary insight on the structural health of existing bridges and to plan a priority list of possible repairing actions in a reasonable, safe, and costly effective manner.

Dynamic Impact Factor Determination of an Existing Pre-stressed Concrete I-Girder Bridge Using Vehicle-Bridge Interaction Modelling

The dynamic Impact Factor (IM) of a bridge is influenced by many factors, including Vehicle-Bridge Interaction (VBI), vehicle speed and road roughness. This paper represents the dynamic effects of moving vehicles and the determination of IM of an existing Pre-stressed concrete I-girder bridge utilizing VBI modeling. Evaluation of the IM is expected to provide valuable information for condition assessment and management of the existing bridge. The interaction problem between the vehicle and the bridge includes a dynamic model for the bridge structure subsystem, a dynamic model for the vehicle subsystem, interaction constraints, road roughness modelling and numerical solution techniques for the dynamic systems. The Half-car model is utilized for modelling of the vehicle dynamics and the bridge dynamic model is idealized according to Finite Element Method (FEM). Then FEM along with the mode superposition method are utilized for determining the Equation of Motion (EOM) for the bridge subsystem. D’Alembert’s principle is used for developing EOM for the vehicle subsystem. The interaction between vehicle vibration and bridge vibration is established through the contact forces between the wheels and the bridge by employing the compatibility relationship between the contact points and by applying the static equilibrium condition. Lastly, Newmark’s-β method is used for solving the coupled mathematical model of the vehicle and bridge interaction problem to determine the responses of the two sub-systems. The whole procedure is then performed for different vehicle speeds and various bridge deck surface roughness conditions to determine the dynamic impact on the existing I-girder bridge named Teesta Bridge located in Bangladesh.

Effect of temperature loading on the performance of a PC bridge in Oklahoma: Reliability analysis

Spatial and temporal temperature variations in bridge structures due to changes in the surrounding climate produce movements which, if restrained, may induce stresses in the structure. Temperature effects have always been considered to be one of the critical issues that affect the performance of prestressed concrete (PC) bridges. In order to (1) develop an efficient temperature loading model for predicting bridge temperature-induced response; and (2) develop guidelines to incorporate the effects of temperature actions in reliability-based condition evaluation, numerical and analytical studies were conducted on a PC girder bridge in Oklahoma, USA. This paper focuses on the structural reliability analysis on the temperature loading action in accordance with AASHTO LRFD specification. A three-dimensional (3D) finite element method (FEM) model was established to estimate the movement and stress under temperature loading, and compared with monitoring counterparts. Then, the validated model was utilized for probabilistic analyses to assess the temperature load effects. Based on the probabilistic temperature loading model proposed in the first paper, loads and resistances statistics from published literature, reliability analyses of AASHTO LRFD limit states were performed by Monte Carlo simulation (MCS) and Rackwitz-Fiessler procedure to determine the safety level in terms of reliability index.

Fatigue reliability evaluation of aging prestressed concrete bridge accounting for stochastic traffic loading and resistance degradation

Fatigue damage accumulation is a critical factor resulting in the failure of prestressed concrete (PC) bridges. The fatigue damage is usually caused by the coupled effect of cyclic vehicle loading and environmental corrosion. This study investigated probabilistic fatigue damage on aging PC bridges considering both stochastic traffic loading and corrosion. A stochastic traffic model was derived based on long-term monitoring data aiming to simulate fatigue stress spectra of critical rebar. The effect of cracks on the fatigue stress spectra was investigated in order to model the fatigue stress state more realistically. A three-stage traffic growth model was established based on traffic volume histories of three highways in China. A fatigue limit state function considering traffic growth and corrosion effect was deduced for fatigue reliability assessment of PC bridges. Numerical results show that the stress amplitude of rebar considering cracks is 1.53 times greater than the rebar with no-cracks, resulting in a decrease of fatigue life by 68 years. In addition, the three-stage traffic growth models lead to 25 years shorter fatigue life than the one considering a linear traffic growth model. Finally, the corrosion effect results in a fatigue life of 44 years. The numerical results provide a theoretical basis for fatigue life estimation and maintenance of aging PC bridges.

Additional Shear Stresses in Webs of Segmental Concrete Bridges due to Anchorage of Cantilever Tendons

The balanced cantilever method is the most widely used technique for the construction of large-span segmental prestressed concrete box-girder bridges. In order to control shear cracks at the service limit state, the principal tensile stresses in the webs are analyzed for all segmental bridges. Web shear cracking may occur for a number of reasons, one of them is the ignoring of shear stresses induced by the anchorage of cantilever tendons during the cantilevering process. This study aims to provide a clear understanding of anchorage-induced shear stresses in the webs of segmental box-girder bridges, including the underlying mechanisms, mechanical models, adverse effects, and design considerations. Case studies show that the peak shear stresses in the webs might have a significant increase due to this localized effect, while it cannot be captured by the beam-element analysis and is usually not considered in the routine design. To solve this problem, a practical approach is developed for evaluating the anchorage-induced shear stresses in the webs of segmental concrete box-girder bridges.

Modal Data Identification of the Prestressed Concrete Bridge Using Variational Mode Decomposition

In this study, the VMD algorithm was used to identify the modal characteristics of the structure using the decomposition of the acceleration responses recorded by the sensors. This algorithm has advantages over other signal decomposition methods that is resistant to the noise and sampling frequency. Also, the VMD algorithm extracts the natural frequencies of the structure concurrently. The damping ratios of the structure were estimated by fitting a linear function to the logarithmic diagram of the modal response in the decaying amplitude and calculating the slope of this line. The efficiency and accuracy of this algorithm were investigated by decomposing the acceleration responses obtained from the sensors installed on a prestressed concrete bridge that is located under the load of passing vehicles. The VMD algorithm was used for signal processing in MATLAB to estimate the natural frequencies, damping ratios and mode shapes of the bridge and ARTeMIS was utilized for verifying the results. The finite element modeling and modal analysis of the bridge were performed in ABAQUS and the natural frequencies and mode shapes of the bridge were obtained. The results showed that the mode shapes estimated by the VMD algorithm was in good agreement with the finite element model and ARTeMIS. Also, the damping ratios estimated by this algorithm were obtained close to the damping value of the prestressed concrete bridge. The difference between the frequencies calculated by the VMD algorithm and ARTeMIS was about 1%, and the difference with the finite element model frequencies was close to 5%.