Concrete Box Girder Bridge Research Articles

Crack-based serviceability assessment of post-tensioned segmental concrete box-girder bridges

Post-tensioned segmental box-girders produce elegant and robust solutions for long-span concrete bridges. Concrete cracking and excessive long-term deflections would greatly impact the in-service performance of this type of structure. This study presents a crack-based approach for the serviceability assessment of cracked box-girders. It is presumed that the excessive prestress loss is the main cause for extensive cracking and excessive long-term deflections in long-span post-tensioned concrete bridges. The approach consists of crack-based mechanical models that link visual crack data to the structure’s critical conditions. Procedures for the flexural-crack based and the shear-crack based assessments are established and applied in the condition evaluation of two real bridges. The proposed procedure employs visual concrete crack data as input, and it provides quantitative output of the in-service performance of cracked box-girders, such as the effective prestress of longitudinal and vertical prestressing tendons, the effective flexural and shear stiffnesses after cracking, and the development of long-term deflections.

Computation of design forces and deflection in skew-curved box-girder bridges

The analysis of simply supported single-cell skew-curved reinforced concrete (RC) box-girder bridges is carried out using a finite element based CsiBridge software. The behaviour of skew-curved box-girder bridges can not be anticipated simply by superimposing the individual effects of skewness and curvature, so it becomes important to examine the behaviour of such bridges considering the combined effects of skewness and curvature. A comprehensive parametric study is performed wherein the combined influence of the skew and curve angles is considered to determine the maximum bending moment, maximum shear force, maximum torsional moment and maximum vertical deflection of the bridge girders. The skew angle is varied from 0o to 60o at an interval of 10o, and the curve angle is varied from 0o to 60o at an interval of 12o. The scantly available literature on such bridges focuses mainly on the analysis of skew-curved bridges under dead and point loads. But, the effects of actual loadings may be different, thus, it is considered in the present study. It is found that the performance of these bridges having more curvature can be improved by introducing the skewness. Finally, several equations are deduced in the non-dimensional form for estimating the forces and deflection in the girders of simply supported skew-curved RC box-girder bridges, based upon the results of the straight one. The developed equations may be helpful to the designers in proportioning, analysing, and designing such bridges, as the correlation coefficient is about 0.99.

Experimental Study on the Effective Temperature Calculation of Concrete Box Girder Bridge

Experimental Study on the Effective Temperature Calculation of Concrete Box Girder Bridge

Probability analysis of web cracking of corroded prestressed concrete box-girder bridges considering aleatory and epistemic uncertainties

Reasonable assessment of web cracking probability is essential to ensure the service performance of corroded prestressed concrete (PC) bridges. In this paper, a time-dependent prediction model of effective prestress for different prestress tensioning techniques and a corrosion propagation model are established. Meanwhile, an assessment approach of web cracking probability considering both aleatory and epistemic uncertainties is proposed. The case analysis results show that the doubled-tensioned prestress technique is obviously more effective in decreasing the web cracking probability than the traditional prestress tensioning technique. The existing probabilistic method that only considers the aleatory uncertainty may greatly underestimate the probability of web cracking. In comparison, the fastest time to reach the threshold value of web cracking probability when considering the epistemic uncertainty is over 11% earlier than that of using the existing methods. Additionally, the epistemic uncertainty of the chloride diffusion coefficient among the selected corrosion parameters has a most significant impact on the probability of web cracking. Therefore, the epistemic uncertainty of corrosion parameters, especially for the chloride diffusion coefficient, should be minimized as much as possible in this assessment process.

The effects of earthquake incidence angle on the seismic fragility of reinforced concrete box-girder bridges of unequal pier heights

The effects of earthquake incidence angle on the seismic fragility of highway bridges of unequal pier heights are investigated. A variety of configurations from regular to so-called highly irregular models are considered. In order to accurately quantify the uncertainties in the modeling process, the most influential sources related to the material properties, earthquake characteristics and structural geometries are considered in the nonlinear simulation. Several three-dimensional bridge models are simulated in OpenSees platform, and a set of strong ground motion records are employed in a series of nonlinear time history analyses of the bridge models. Different incidence angle of the records have been used to investigate the response of the models and to extract the most critical engineering demand parameters. The system and component fragility parameters are developed and compared for different values of the excitation angles for all the bridge models. Given the wide range of variables used here, a conversion coefficient is proposed to convert the bridge response for different incidence angles to critical response.

Bridge Deck Replacement of Posttensioned Concrete Box-Girder Bridges

Abstract This paper studies the feasibility of replacing damaged deck of posttensioned concrete box-girder bridges without the use of falsework to support the superstructure span. Parameters of the...

Seismic Response Evaluation of Composite Steel–Concrete Box Girder Bridge according to Aging Effect of Piers

현재 우리나라에서 운영 중인 교량 중 30년 이상 된 교량이 전체의 약 11%를 차지할 정도로 노후교량의 수가 증가하고 있다. 따라서 교량의 노후화에 따른 영향을 고려한 내진성능 평가방법의 개발이 필요하다고 볼 수 있다. 예제 교량으로는 포트받침, 탄성고무받침과 납-고무받침을 가진 3가지의 강합성 상자형 거더교를 선정하고, opensees 프로그램을 사용하여 구조해석모델을 작성하였다. 본 연구에서는 교량의 노후도를 교각의 주철근과 띠철근의 부식에 의한 면적의 감소로 반영하였다. 교각의 노후화 정도로는 5%, 10%, 25%, 50%의 4가지 조건을 사용하였다. 입력지진으로는 근거리 지진과 원거리 지진을 각각 40개씩 사용하였으며, 노후화 정도에 따른 예제교량의 교각에 대한 최대변위와 최대 전단력 응답을 구하여 비교하였다. 노후도가 증가할수록 힘-변위 관계에서 교각의 강도저하가 발생함을 알 수 있으며, 이로 인하여 교각의 변위응답이 증가함을 알 수 있다. 교각의 노후도에 따른 변위응답과 전단저항능력의 영향을 분석하기 위하여 변위비(Dratio)와 전단력비(Fratio)를 정의하여 평가하였다. 예제교량의 고유주기가 길어질수록 노후도에 따른 변위비(Dratio)의 증가가 크게 나타남을 알 수 있으며, 전단력비(Fratio)의 감소 경향은 작게 나타남을 알 수 있다.

Study on the time-varying temperature field of small radius curved concrete box girder bridges

Bridges might have time-varying sunlit–shaded areas due to the rotation and revolution of Earth. This work aims at studying the effects of time-varying sunlit–shaded areas on the temperature field of small radius curved concrete box girder bridges. Based on the law of Earth’s rotation and revolution, the solar position is first obtained by considering the relative position between the Sun and the location of the bridge site on Earth. Then, the sunlit–shaded areas of small radius curved concrete bridges are determined using the ray tracing algorithm. With the consideration of various environmental conditions, including the time-varying solar radiation and wind speed, the three-dimensional finite element model of a small radius curved concrete bridge is created in ANSYS and the temperature field of the bridge could be solved. With a 30 m long curved concrete bridge taken as an example, the temperature distribution profiles of the bridge are investigated. The results and analysis provide a good reference for the thermal analysis and design of small radius curved concrete bridges.

A Mahalanobis Distance Cumulant-Based Structural Damage Identification Method with IMFs and Fitting Residual of SHM Measurements

Data-driven damage identification based on measurements of the structural health monitoring (SHM) system is a hot issue. In this study, based on the intrinsic mode functions (IMFs) decomposed by the empirical mode decomposition (EMD) method and the trend term fitting residual of measured data, a structural damage identification method based on Mahalanobis distance cumulant (MDC) was proposed. The damage feature vector is composed of the squared MDC values and is calculated by the segmentation data set. It makes the changes of monitoring points caused by damage accumulate as “amplification effect,” so as to obtain more damage information. The calculation method of the damage feature vector and the damage identification procedure were given. A mass-spring system with four mass points and four springs was used to simulate the damage cases. The results showed that the damage feature vector MDC can effectively identify the occurrence and location of the damage. The dynamic measurements of a prestress concrete continuous box-girder bridge were used for decomposing into IMFs and the trend term by the EMD method and the recursive algorithm autoregressive-moving average with the exogenous inputs (RARMX) method, which were used for fitting the trend term and to obtain the fitting residual. By using the first n-order IMFs and the fitting residual as the clusters for damage identification, the effectiveness of the method is also shown.

Long‐term performance monitoring and assessment of concrete beam bridges using neutral axis indicator

Long-term performance of existing bridge structures provides stakeholders with information that facilitates decision making for reasonable and optimal maintenance and management. The neutral axis (NA) is a potentially reliable and robust indicator to evaluate bridge performance since it depends on the loss of elastic modulus or effective sectional area. In this study, the NA indicator is defined and derived, and it is combined with the statistical characteristics of the NA distribution, to assess long-term structural performance. A systematic long-term performance assessment framework based on NA is also proposed. The NA is estimated from strain measurements and related practical signal processing methods. To validate the proposed framework, strain signals acquired from a preinstalled structural health monitoring system on an existing concrete beam bridge were analyzed. For the long-term performance assessment, an NA database was established. The statistical characteristics of the NA sample in the daily evaluation cycle were obtained to evaluate the performance. The results show that different cross sections have their own estimated NA; and during the monitoring period, the NA indicators fluctuate within a reasonable range. With the increase of monitoring data, these results can be continually updated. It can be concluded that the proposed NA indicator, along with the related framework, can be employed effectively in the condition assessment of concrete box girder bridges for long-term health monitoring.

Fragility Assessment for Horizontally Curved Reinforced Concrete Box Girder Bridges Using As-built Data

Damage to one or multiple components of a bridge could result in various conditions, extended from a cosmetically repairable damage to jeopardizing life safety of the users. Fragility curves are beneficial in seismic risk assessment. Due to the limitations of the transformation network, aesthetic considerations, etc., a bridge might be skewed or curved which makes the problem more complex. Fragility assessment of bridges utilizing dynamic analysis seems to be inevitable in reducing damage levels in future earthquakes. In this study, the effectiveness of adopting fragility curves in performance evaluation and risk assessment of bridges is investigated. It is done by considering a highway curved bridge with eleven piers. FEM model is developed using OpenSees platform. Time history dynamic analysis is used to obtain the displacements and forces as demands of each bridge component. Eventually, fragility curves are developed for four damage states. Pier fragility curves of this bridge depict a very appropriate behavior under various levels of excitation which could be related to the appropriate distance of the stirrups. Prevalent mode of the bridge causes torsion in the first bay of the bridge. In the other two bays, only longitudinal transfer of the deck was observed. Bearing fragility curves of the bridge depict fair results in the transverse direction due to the presence of the shear keys as opposed to the longitudinal direction.

Numerical Analysis of Temperature Influence on Transverse Cracks in Concrete Box-Girder Bridges

Concrete box-girder bridges are widely used in China. During several routine inspections of two-year-old highway bridges of this type in the China Central Plains region, we found that transverse cracks are widespread on the bottom flanges of those box girders, mainly distributed in the area of 1/4L to 3/4L of the span. Selected cracks were then monitored continuously for one year. Our results showed that there had been no change in the widths of the cracks, but their lengths had increased and new cracks had formed. Taking into consideration factors like hydration reaction, relative humidity difference, shrinkage and creep, sunlight thermal differential effect, sudden temperature change, vehicle load, and their combined efforts, we have developed spatial structural models and conducted stress analyses on the reinforced concrete and prestressed concrete box-girder bridges, respectively. Our numerical analysis results indicated that the hydration reaction is the main reason for the initial bottom flange crack and the temperature difference between the inside and the outside of the box girders caused the crack developments at the later stage.

A novel asynchronous-pouring-construction technology for prestressed concrete box girder bridges with corrugated steel webs

Owing to the superior mechanical performance and material efficiency, the combination of prestressed concrete (PC) slabs and corrugated steel webs (CSW) as PC girder with CSWs (PCGCSW) is extensively applied to railway and highway bridges. To overcome the shortcomings of traditional balanced cantilever construction (TBCC) of PCGCSW, reduce environmental impact, and promote sustainable construction, a novel asynchronous-pouring-construction (APC) technology is introduced in this paper. This improved method makes full use of the excellent shear capacity of the corrugated steel webs (CSWs) to support the hanging basket, increases the construction platforms to accelerate the construction speed. Based on a practical project of a long-span composite box girder bridge with CSWs in China, the construction process of the APC method is systematically introduced, and the structural safety and environmental sustainability of such bridge using APC technology are evaluated and compared with that using TBCC. The comparison results indicate that APC method can reduce the compressive stress of top concrete slab, but slightly increase the shear stress and deflection during the cantilever construction stage because the hanging basket is directly supported by CSWs. Besides, the weight of the improved handing basket in APC technology is reduced up to half in comparison that in TBCC. Accordingly, the APC technology saves a lot of energy consumption, reduces huge CO2 emissions for construction equipment, and shorts construction period. Therefore, the utilization of APRC technology can ensure the bridge’s safety and reliability, effectively accelerate construction speed, reduce the construction load, decrease the environmental pollution, and save the engineering cost, which can be regarded as a sustainable and environmental-friendly construction method for composite bridges with CSWs.

Analysis of RCC T-beam and prestressed concrete box girder bridges super structure under different span conditions

A bridge is a structure that provides passage over an obstacle without closing the path below. The required crossing may be for a road, rail, pedestrian, canal, or pipe. For constructing the bridges has many types of sections among which Tee beam and Box girder bridges have selected. T-beam bridges are cast-in-situ bridges, popular for short spans and economical. Similarly, the widely used box girder bridge selected which is economical for long spans, that may be either single or multi-celled girder. The type of bridge is concerned with providing maximum efficiency of material and construction technology. As the span increases, the dead load that is an important growth factor also increases. To reduce dead load, unnecessary material, which not used to its full potential, is removed from this section, which can be in the shape of box girders or cellular structures depending on whether the shear deformations neglected or not. In the present study, a two-lane simply supported RCC Tee beam girder and prestressed concrete box girder bridge analyzed and designed for dead load and IRC moving loads, where the considered moving load is of the tracked vehicle of class A-A loading. Courbon's method adopted for analysis and designing. Dead load and live load calculations have done manually. Shear force and bending moment for a vehicular load have calculated. Piguead's curves used for bending moment calculations. The main objective of this paper is to check whether both the T and box girder bridges have adopted for the assumed data with different span conditions.

Failure mechanism investigation of bottom plate in concrete box girder bridges

In the proposed study, the Linguo continuous rigid frame bridge was studied to determine the failure mechanisms combining both field investigation and a 3D finite element (FE) method. The characteristics of the failure on the bottom plate were analysed and three typical failure models are identified. The failure mechanism was investigated and verified using a proposed 3D nonlinear FE model. Retrofit methods are proposed and implemented for the damaged bridges. The measured stress response and calculated stress response from the proposed 3D finite element model are compared. Satisfactory results are observed between field measurements and numerical simulations. Parametric studies are performed using the developed model to investigate several important parameters for the bridge design and construction. Finally, conclusions and recommendations for future bridge analysis and design were provided on the basis of the proposed study.

Inelastic seismic response of box-girder bridges due to torsional ground motions

The torsional components of strong ground motions (TGMs) may result in unanticipated displacement and force demand particularly in highway bridges due to their complex dynamic characteristics. For this purpose, the present study investigates the effects of TGMs on the inelastic seismic response of continuous concrete box-girder highway bridges with seat type abutments. Three-dimensional finite element (3D FE) models of bridges with varying skew angles, number of bent columns, and column height-to-diameter ratios were developed using OpenSees, and a series of nonlinear response history analyses were conducted. Comparison of seismic response of bridges subjected to only translational and both translational and TGMs revealed that TGMs may result in uneven and asymmetric failure of the shear keys. Therefore, deck rotations are significantly amplified due to induced instantaneous eccentricity when deck comes in contact with shear key(s). The amplified impact forces due to TGMs further amplify the deck rotations, which in return result in higher inelastic displacement and force demand. Last but not the least, the induced torsion due to TGM combined with axial-flexure-shear interactions may result in complex failure modes, higher shear stresses, and reduction in lateral deformation and flexural capacity of the bridge columns.

Static Strength of Friction-Type High-Strength Bolted T-Stub Connections under Shear and Compression

The friction-type high-strength bolted (FHSB) T-stub connection has been widely used in steel structures, due to their good fatigue resistance and ease of installation. While the current studies on FHSB T-stub connections mainly focus on the structural behaviors under both shear and tensile force, no research has been reported on the mechanical responses of the connections under the combined effects of shear and compression. To make up for this gap, this paper presents a novel FHSB T-stub connection, which is simple in structure, definite in load condition, and easy to construct. Static load tests were carried out on 21 specimens under different shear–compression ratios, and the finite-element (FE) models were created for each specimen. The failure modes, initial friction loads and ultimate strengths of the specimens were compared in details. Then, 144 FE models were adopted to analyze the effects of the friction coefficient, shear–compression ratio, bolt diameter and clamping force on the initial friction load and ultimate strength. The results showed that the FHSB T-stub connection under shear and compression mainly suffers from bolt shearing failure. The load–displacement curve generally covers the elastic, yield, hardening and failure stage. If the shear–compression ratio is small and the friction coefficient is large, its curve only contains the elastic and failure stage. The friction coefficient and shear–compression ratio have great impacts on the initial friction load and ultimate strength. For every 1 mm increase in bolt diameter, the initial friction load increased by about 10%, while the ultimate strength increased by about 8.5%. For each 10% increase/decrease of the design clamping force, the initial friction load decreases/increases by 7.8%, while the ultimate load remains basically the same. The proposed formula of shear capacity and self-lock angles of FHSB T-stub connection can be applied to the design of CSS-enhanced prestressed concrete continuous box girder bridges (PSC-CBGBs) and diagonal bracing.

Experimental and Numerical Investigation on the Anchorage Zone of Prestressed UHPC Box-Girder Bridge

Abstract The structural behavior of the anchorage zone is a key issue in prestressed ultra-high performance concrete (UHPC) box-girder bridges. This study investigates the mechanical behavior of a ...

Shrinkage test of concrete: Methodology and variation of strain

Evaluation of shrinkage strain in long concrete structures such as prestressed concrete box girder bridges is very important for the design of such structures. A wrong evaluation may contribute to loss of prestressing force, excessive deflections, cambers and cracking of the structure. It may also affect the durability and serviceability of the structure. The value of shrinkage strain is required during design, far before the construction process. However, realistic evaluation is still a difficult problem because shrinkage strain is influenced by the concrete composition and environmental factors such as humidity and temperature. Therefore, to gain the best evaluation, an experimental program was conducted to measure the shrinkage strain of concrete versus concrete age. Several concrete specimens were collected during pouring of several box girder segments of Tauranga Harbour Link, New Zealand. Variation of shrinkage strain versus concrete age for almost two years of data collection was plotted.

Experimental Study of the Temperature Distribution in CRTS-II Ballastless Tracks on a High-Speed Railway Bridge

To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h).