Concrete I-girder Research Articles

Shear performance of 25 m full-scale prestressed UHPC-NC composite I-beam without stirrups

The burgeoning preference for prestressed Ultra-High Performance Concrete (UHPC) I-girders without stirrups, stemming from the remarkable tensile strength of UHPC, indicating a promising trajectory for future construction endeavors. This research delved into real-world engineering scenarios, focusing on shear tests conducted on both 9.0m and 6.5m segments cut off a 25.0m full-scale prestressed UHPC-NC composite I-beam without stirrups, which had already undergone flexural failure. Employing Finite Element Models (FEM), the study scrutinized and forecasted test outcomes. In asymmetric loading shear test, the end with a lower shear span ratio and higher shear capacity fails earlier. Subsequently, a validated FEM, reflective of the tested beam, was established. Leveraging this validated model, a comprehensive analysis ensued, probing into parameters influencing the shear performance of the full-scale prestressed UHPC-NC composite I-beam without stirrups. Parameters under study encompassed the prestressed tension level, web width, and shear span ratio. Findings revealed minimal impact of prestressed tension level on the shear performance of the tested beam, with augmented web width substantially enhancing stiffness and shear capacity. Conversely, an increase in shear span ratio correlated with a decline in shear performance of the tested beam. Finally, it juxtaposed various predictive equations for the shear capacity of the beams without stirrups from disparate global locales, advocating for the utilization of equations outlined in the French equation to predict the shear capacity of the tested beams in this study, aiming for minimized margin of error and conservative estimation.

Book review

Book review

Load distribution factors for quick design and assessment in typical Australian bridges

ABSTRACT The increase in freight productivity in Australia is pressuring Australian bridge infrastructure. Bridge assessment is crucial to ensure the safety of bridges to accommodate heavier vehicles. Load distribution factor (LDF) has been widely used for bridge design and evaluation in the preliminary stage, but it is not specified in the Australian standard code. This study aims to develop the LDFs for typical Australian bridges with the most adverse load effects of single- and two-lane loads. Later, the LDFs were compared with the LDF equations in the different standards, including National Association of Australian State Road Authorities (National Association of Australian State Road Authorities, 1976), American Association of Highway and Transportation Officials: Load and Resistance Factor Design (AASHTO (2017), Henry’s and modified Henry’s methods. It can be concluded that the AASHTO (2017) LDF equations provide very good correlations with typical Australian bridges. It is possible to use the AASHTO LRFD LDF equations for assessing and designing in Australian concrete I-girder and Super-T girder bridges. However, most AASHTO LFRD provides conservative results of LDFs compared with LDFs of Australian bridges. It is recommended that LDFs of Australian bridges should be developed for bridge design and assessment.

Numerical Investigation of Cracks at Girder Ends of Prefabricated Post-Tensioned Prestressed Concrete I-Girders

Prefabricated post-tensioned prestressed concrete (PTC) girders with high degrees of prestressing have been developed continuously in recent bridge designs to reach longer spans, higher quality, and larger load-bearing capacity. However, during the prefabrication process, several inclined and horizontal cracks were observed at the ends of a new style post-tensioned concrete girder, which could have a negative impact on the girders' longevity. In this study, a nonlinear finite element analysis technique was utilized to illustrate how concrete reacts and the mechanisms behind typical cracking patterns during the actual post-tensioning sequence. The prestressing load of a PTC girder was simulated with an improved cooling temperature method that accounts for immediate prestress losses. The field of principle tensile strain patterns and primary strain trajectories explained the overall mechanism underlying typical cracking behaviors. The results showed that the horizontal cracks under the anchorage plate (behavior 1) were generated by the bursting force, whereas the inclined cracks (behavior 2) and the horizontal cracks between the strands N1 and N2 anchor plates (behavior 3) were caused due to the spalling force. The effects of self-weight, girder end forms, as well as the transfer length of the prestressing strands, were discussed. The result demonstrates that both the self-weight and girder end shapes have a considerable effect on the behaviors of the anchorage zone. It is suggested that the transfer length of the anchor head be greater than 26 times of strand diameter to achieve the same effective stresses as the theoretical values.

Effect of concrete mixture on shear behavior of prestressed concrete girders

A total of six shear-critical prestressed concrete (PC) I-girder were tested to investigate the effect of concrete mixture types on the shear behavior of PC girders. The concrete mixtures examined were conventional concrete (CC), high-performance concrete (HPC), and self-consolidating concrete (SCC) with normal (specified fc′=41.4 MPa) and high (specified fc′=68.9 MPa) compressive strengths. Test results showed that the HPC girders exhibited a shear behavior similar to the CC girders, irrespective of the concrete compressive strength. The SCC girder with normal-strength concrete (SCC-N) showed a higher ultimate shear strength ratio (Vult/Vn) and higher ultimate displacement than the corresponding CC girder (CC-N). The SCC-N mixture was designed with a similar coarse aggregate amount but a reduced maximum coarse aggregate size compared with the CC-N mixture. The better performance of SCC-N may be attributed to a better filling ability of the SCC-N mixture than the CC-N mixture. The SCC girder with high-strength concrete showed a lower Vult/Vn than the corresponding CC girder (CC-H). The lower shear strength of the SCC girder may be attributed to the lower coarse aggregate amount (19% lower) than the CC-H girder. A shear test database of PC girders was established to investigate further the effect of coarse aggregate amount on the girder shear strength. Based on the statistical analysis, the Vult/Vn and coarse aggregate amount either showed a positive or insignificant correlation. For those groups of test data that showed positive correlation, the slopes of the linear regression of the test data showed that for a 100 kg/m3 decrease of coarse aggregate amount, the Vult/Vn decreased in average by 18.5%.

Effect of Shear Deformation at Segmental Joints on the Short-Term Deflection of Large-Span Cantilever Cast Prestressed Concrete Box Girders

The excessive deflection of large-span cantilever cast prestressed concrete (LCCPC) box girders has always been a complex problem to be solved in bridge engineering. To analyze the effect of shear deformation at segmental joints on the deflection of LCCPC box girders, comparison tests were carried out on three prestressed concrete (PC) I-girders with joints and a PC I-girder without joints, and a finite element simulation method of segmental joints was proposed based on the tests. Subsequently, finite element analysis was conducted on a test girder and the Assistant Shipping Channel Bridge of Humen Bridge (a PC continuous rigid frame bridge with a main span of 270 m) using this method. The experimental and theoretical analysis results showed that the effect of the shear deformation at joints compared to the deformation at midspan of the girder specimens was negligible. Deformation at midspan of the specimens would not significantly increase, even if shear rigidity at the joints was significantly reduced or there were more joints in the girder specimen. The effect of shear deformation at segmental joints on the deflection of LCCPC box girders was quite small and thus insignificant.

A statistical index based damage identification method of a bridge using dynamic displacement under moving vehicle

Potential damage identification is essential to avoid the sudden and premature failure of aging bridges, which have attracted ample attention over the decades. This paper proposes an output only data driven technique for damage identification which will not require any physical model of the structure nor any known input excitation. Statistical moments have been considered as the key feature for the proposed method of damage identification which has been derived from the measured vehicle-induced dynamic displacement responses of a pre-stressed concrete I-girder bridge. The displacement responses data of a bridge is influenced by many factors, including Vehicle-Bridge Interaction (VBI), vehicle speed and road roughness. The interaction between vehicles and bridges includes dynamic models for bridge structure subsystem and vehicle subsystem, interaction constraints and road roughness modelling. Firstly, the coupled formulation is derived based on the interaction constraints. Then, Newmark’s β method is utilized for solving the coupled VBI problem to extract the vehicle-induced displacement responses. Later, the statistical moment is calculated from the Power Spectral Density (PSD) of the displacement response retrieved from sensors positioned on the span of the bridge for both damaged and undamaged conditions. A damage index named Curvature of Statistical Moment Difference (CSMD) is calculated to identify the damages. Artificial damage is incorporated through the reduction of structural stiffness of the bridge element. The results of the study demonstrate the method's capability to identify and locate damage at any position of the bridge span and assess the relative severity of the damage. The effect of varying pavement roughness conditions is also considered in this study.

Practical ultra-high-strength concrete for precast concrete applications

This paper focuses on developing ultra-high-strength concrete (UHSC) with mechanical properties compara­ble to those of ultra-high-performance concrete (UHPC) and with production procedures similar to those used for high-strength concrete. A concrete mixture was developed to achieve a compressive strength of 17 ksi (117 MPa) at 28 days without using silica fume and with a slump flow as high as 35 in. (889 mm). Another concrete mixture with compressive strength of 20 ksi (138 MPa) was designed using only 130 lb/yd3 (77.1 kg/m3) of silica fume. In addition to these two mixtures, a UHPC mixture was also designed with a compressive strength of 24 ksi (165 MPa). Laboratory tests were conducted to investi­gate predictions of modulus of elasticity, flexural strength, creep, and shrinkage for the developed mixtures. This paper demonstrates that using UHSC and 0.7 in. (18 mm) diameter strands will produce adequate flexural strength to design 300 ft (91.4 m) long prestressed concrete I-girders that have service stresses within safe limits

Influence of Seismic Loads Considering Soil Properties and Wave Passage Effect on the Seismic Response of a Multi-Span PSC Girder Bridge

This paper investigates the analytical results of the seismic response of multi-span prestressed concrete (PSC) I-girder bridges under seismic loads. To perform numerical analyses, a three-span PSC I-girder bridge with a width of 12 m, a total length of 100 m, and a maximum span length of 40 m was modeled, and a virtual location was selected to consider the soil properties of the area where the bridge was constructed. The seismic load acting on the PSC I-girder bridge was applied in consideration of the soil properties around the pier and the wave passage effect of the bedrock in the artificial seismic load generated, according to the U.S. Nuclear Regulatory Commission (NRC) standard. The analysis results confirmed that the seismic load, with consideration of the soil properties and wave passage effect, generated the maximum response acceleration and bending moment at the deck of the bridge—152% and 232% greater than without considering them, respectively. Therefore, in order to ensure the earthquake resistance of the bridge, the soil properties of the area where the bridge will be built and the wave passage effect of the bedrock must be considered.

Reliability analysis of typical highway bridges in Manitoba designed to the Modified HSS-25 live load model

Several provinces in Canada have modified the live load model specified in national bridge design codes to account for locally permitted trucks. Manitoba similarly introduced a live load model for the design of provincial bridges in accordance with AASHTO LRFD, the Modified HSS-25. This article presents truck weight datasets and methods used to develop Manitoba-specific live load statistics to conduct a reliability analysis for three typical simply supported structure types: precast prestressed concrete box girder, precast prestressed concrete I-girder and steel girder. The average reliability indices ranged from 4.69 to 4.95 with respect to the AASHTO LRFD live load statistics used to calibrate the code and 4.65 to 5.04 with respect to the Manitoba statistics. The results demonstrate a level of safety that exceeds the code requirements, indicating that structures designed to the HSS-25 potentially possess the structural capacity to withstand increased vehicular load effects for the considered bridge types.

Safe Platooning Headways on Girder Bridges

Truck platooning—digitally linking two or more trucks to travel in a closely spaced convoy—is an emerging technology with the potential to save fuel and reduce labor. A framework is described to determine how much a platoon permit load might be increased above Federal Bridge Formula B legal limits, given strict control over the load characteristics and operational tactics. Soon, platoons are expected to advance not only with respect to traffic operations but also in their ability to weigh and report axle weight and spacing, functioning as mobile weigh-in-motion vehicles. Consequently, platoon live load statistics (bias and coefficient of variation) can differ from code assumptions, and are perhaps controllable, which poses a significant opportunity with respect to operational strategies. A parametric study is presented that examined safe headways between platooning trucks, considering different girder spacings, span lengths, numbers of spans, types of structure, truck configurations, numbers of trucks, and adjacent lane loading scenarios. The Strength I limit state was evaluated for steel and prestressed concrete I-girder bridges optimally designed using load and resistance factor design. Reliability indices, β, were calculated for each load case based on Monte Carlo simulation. Summary headway guidance was developed and is presented here to illustrate potential safe operational strategies for varying truck weights and platoon live load effect uncertainties.

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.

PERENCANAAN ULANG STRUKTUR ATAS PADA FLYOVER TELUK LAMONG MENGGUNAKAN I-GIRDER

Efforts to move the government in the infrastructure sector require related reference support. One form of reference can be an analysis of the use of prestressed concrete I-girder on the Teluk Lamong Flyover with the aim of knowing the dimensions of the upper structure elements used, the tendon system, and the amount of stress, shear force, deflection, moment. The results obtained from this analysis are in the form of girder type PC I H-170, the dimensions of the floor plate 1.85 x 1.00 x 0.20, 0.16 x 0.20 x 1.00 back pile and using galvanized steel pipe Ø 76.3 mm BJ-37. 6 tendons, filled with 7 strands per tendon, 15.2 mm in diameter belongs to OVM. With the largest stress of (-478.1630439) kPa, the largest shear force of 1045,532 kN, the largest deflection of 0.03753583 m, and the greatest moment of ultimate value of 8800.235061 kNm.

Dynamic Performance of a New-Type PSC I-girder for Railway Bridge Application

This study intends to verify analytically and experimentally the performance of a new type of prestressed concrete (PSC) I-girder for its application as railway bridge. Since the girder-type railway bridge develops relatively low torsional rigidity, there is risk for the dynamic responses to amplify due to the superposition of the torsional mode and flexural mode. The superposition of the torsional and flexural modes as well as the dynamic stability of the railway bridge were examined through dynamic analysis. Three-dimensional modelling was built to be suitable for carrying out moving load analysis. Four different span lengths of 30, 35, 40 and 45 m adopted considering the most applied span length currently and future lengthening of the span length. Moreover, a full-scale girder specimen with span length of 35 m was fabricated and subjected to dynamic loading. The measured dynamic responses were then compared to the analytic values. Finally, the ultimate bearing capacity of the specimen was verified by static loading test.

Development of Robotic Nondestructive Testing of Steel Corrosion of Prestressed Concrete Bridge Girders using Magnetic Flux Leakage System

This paper describes the development and validation of a new magnetic-based corrosion detection device integrated in a robotic system. The system nondestructively scans the length of AASHTO-type prestressed concrete I-girders of bridges. The system includes two primary subsystems: an independent magnetic flux leakage (MFL) system for nondestructive testing, and a robotic rover to transport the MFL system along the girder’s length with navigation around transverse diaphragms. The MFL unit inspects prestressing steel strands embedded in concrete and detects cross-section losses caused by corrosion. The MFL is designed with two permanent magnets to magnetize embedded strands and multiple Hall-effect sensors to detect normal and axial magnetic flux leakage. The system is evaluated by testing a laboratory mockup girder and further applied on a field girder. Resulting magnetic signals from both normal and axial Hall-effect sensors are recorded using a newly developed and integrated data acquisition system. Finite element simulations through multi-physics 3D transient analysis aided the development of the new MFL system components, including appropriate magnets strength and dimensions, as well as the verification of the developed system. The effects of lateral reinforcements on nearby section loss are obtained from tests and analyzed with numerical models. Results indicate that the system can successfully disclose magnetic leakage signals at the corrosion zone.

Time-dependent behaviour prediction of the prestressed HPC I-girder

A time-dependent behaviour prediction of the prestressed concrete I-girder made from high-performance concrete (HPC) is very difficult. Overestimation or underestimation of the deflection (camber) and prestress loss may be affecting their service life and even also a failure. In this study, time-dependent behaviour of the prestressed I-girder was predicted using experimentally measured material properties data of HPC, i.e., shrinkage, creep and modulus of elasticity. Four independent HPC mixes of M50 grade concrete were designed as per IS 10262 and considered as a reference mixes to study its influence on the time-dependent behaviour of prestressed I-girder. HPC Mix-I, was prepared only using ordinary Portland cement (OPC) while others Mix-II, Mix-III, and Mix-IV were prepared using OPC as the main binder with the addition of one supplementary cementitious material (SCM), i.e., fly ash (FA), silica fume (SF) and ground granulated blast-furnace slag (GGBS). A validated incremental time-step analysis method was adopted to predict deflections, fibre stresses and prestress losses up to 1106 days (3 years) of prestressed I-girder.A predicted time-dependent behaviour is a good agreement with field measured data when the analysis method is used experimentally measured properties of concrete. A comparative appraisal using estimated material properties from the existing material models (i.e., ACI, FIB, B3, GL, and ANN) with experimental test data has also been done to find their reliability for HPC prestressed I-girder. A time-step analysis method can provide an accurate prediction of the time-dependent behaviour of HPC prestressed I-girder, if the measured material properties considered as an input parameter.

Temperature Gradients in Bridge Concrete I-Girders under Heat Wave

This research is supported by the University of Arkansas at Fayetteville, Ton Duc Thang University, and Southern Plains Transportation Center. The authors are thankful to a number of graduate students for their help during the experimental program.

Prestressed Concrete I-Girder Optimization via Genetic Algorithm

Prestressed concrete has been gaining popularity in the construction industry because of its many advantages, which include reduced dead load due to less material used and overall cost savings. Nonetheless, a single prestressed concrete I-girder as a structural element in highway bridges is still significantly costly and massive, so optimization can yield a significant amount of cost savings as well as reduced material consumption. In this study, prestressed concrete I-girder optimization was carried out by implementing a genetic algorithm (GA), a method inspired by nature's evolution and natural selection. This study evaluates a number of aspects of applying a genetic algorithm for optimization of material cost of a prestressed concrete I-girder design. A new method for calculating the fitness value is proposed, which was proven to be essential for the application developed in this study. The best solution that resulted from the optimization process is presented, defined by being the least costly solution while still maintaining compliance with the AASHTO LRFD 2007 design code, which includes ultimate strength, service stresses and deflection, detailing requirements, geometrical feasibility, etc. Lastly, a sensitivity analysis was carried out, discussing the influence of the starting conditions on the output of the optimization process.

Destructive testing and computer modeling of a scale prestressed concrete I-girder bridge

Currently, there is a limited amount of published information on failures of prestressed concrete bridges subjected to shear and moment. A scale prestressed concrete bridge was constructed to investigate the ultimate behavior of the bridge with particular focus on load distribution after cracking and on contribution of full-depth diaphragms to structural capacity. A point load was applied at the quarter-span point of the bridge over an interior girder. As the loaded girder failed, the diaphragm-girder connection cracked. Torsion was observed to cause cracking in the exterior girder and the end diaphragm rotated away from the bridge as the deck deformed. A punching shear failure ended the test, however damage indicative of two-way slab behavior was observed in the deck. This failure suggests that post girder failure, the diaphragms provide an important means of load transfer, allowing moment redistribution in the deck and potentially increasing capacity. Testing in the elastic range compared favorably with respect to deflections and shear distribution factors from a grillage model, a 2-D finite element model and a 3-D finite element model.

Material quantity estimation modelling of bridge sub- substructure using regression analysis

In construction field, a time completion and an adherence to budget are two factors that mainly influence the successful of the projects. The adherence to the budget can be achieved when the estimated budget is closed to the actual cost. For the owners, cost estimation is necessary as a guidance in determining the amount of investment. Therefore, it is very important to know the estimation of the project cost by using the limited data before the detailed plans and specifications of the project are identified. However, in the case of bridge substructure preliminary cost estimation, there is a lack information about material quantity estimation models due to the difficulties of soil characteristic and hydrological conditions. Hence, this research aims to develop the estimation of material quantity models of the abutment and caisson of bridge, with the Presetressed Concrete I-Girder (PCI Girder) superstructure located in Sleman district, Yogyakarta province, Indonesia. The database used for developing model was obtained by conducting sub-structure structural analysis of 15 abutments and 45 caissons. The bridges have a various span length, abutment height, and caisson depth. Material quantity estimation models were analysed by the multiple regression analysis methods. The span length and the abutment height are determined as independent variables to predict the concrete volume, the reinforcing steel weight, the caisson concrete volume, the cyclops concrete volume and the caisson reinforcing steel weight. This research proposed 11 equation models to estimate the concrete volume and reinforcing steel weight of abutment and caisson.