Bridge Pylon Research Articles

Parametric Design of Scroll-shaped Pylon of Single Tower Cable-stayed Bridge

Parametric Design of Scroll-shaped Pylon of Single Tower Cable-stayed Bridge

Impact force-damage depth model for ship-bridge collision

The impact force-damage depth model, i.e., P-a model, provides a feasible approach to design and evaluate bridge resistance under ship collisions, which is inadequately addressed in the existing specifications and literature. In the present study, based on an 18500 DWT (deadweight tonnage) bulbous bow bulk carrier and the main tower of cable-stayed bridges, the P-a model for ship-bridge collision is established with consideration of pile cap, bridge pylon and striking ship. Firstly, the refined finite element (FE) model of prototype ship was established with detailed modeling of both the main and stiffening components. The material model parameters and FE analysis approach were validated through the existing tensile tests on marine steel coupons and crush tests on ship bow specimens. It is found that the modeling of stiffening components has rationality in predicting the impact force and asymmetrical folding collapse of ship bow. Then, concerning two collision scenarios with the main tower of cable-stayed bridges, i.e., only bulbous bow-pile cap collision and sequential bulbous bow-pile cap and bow overhang-bridge pylon collisions, the influences of nine critical parameters from pile cap (height, curvature and water level), bridge pylon (width, curvature, angle and bow overhang-bridge pylon distance) and striking ship (mass and velocity) on the impact forces and failure patterns of ship bow were comprehensively discussed. It indicates that: (i) the larger impact forces of bulbous bow and bow overhang appear with increased pile cap height, decreased bridge pylon curvature and inward inclined pylon angle; (ii) the loading paths of P-a relationships are approximately identical with different striking ship masses and velocities. Finally, the P-a model for ship-bridge collision was established by response surface methodology, and the corresponding calculation procedure was further given and validated.

Forensic Analysis on Damage of a Cable-Stayed Bridge without Backstays Using BIM Information

Serious cracks were found in the pylon of a cable-stayed bridge without backstays. Based on forensic damage investigation, this paper uses the finite element (FE) method incorporating Building Information Modeling (BIM) to analyze the causes of cracking. The BIM model is established based on the survey of design, construction, and service information of the bridge. Then, FE analysis is conducted using BIM information. Finally, the causes of cracking in different regions of the pylon are explained in detail. The results show that the FE simulation agrees well with the inspected distribution of cracks, and the causes of cracks are closely related to the pylon construction process. The main cause of the cracks is the shrinkage difference between concrete segments of different ages. The anchorage effect of stayed cables also causes inclined cracks perpendicular to the cable direction. The combination of temperature load and concrete shrinkage results in cracks at the root of the pylon, and the reduction in cable forces exacerbates the cracking.

Design and optimization analysis of pylon open lower corbel

This study, centered around the engineering context of the Wuxue Yangtze River Bridge, addresses the challenge of significant temperature-induced secondary internal forces in the short lower tower column. A novel open lower corbel tower scheme is proposed as a solution. Firstly, comprehensive finite element models are established for both the open lower corbel pylon scheme and the traditional lower continuous beam pylon scheme. These models are employed for finite element analysis to derive bending moments and displacements of the bridge pylon under various loads, including permanent, vehicle, temperature, and wind loads. Subsequently, considering internal force distribution and stiffness, a comparative assessment is made between the open lower corbel cable pylon scheme and the traditional lower continuous beam cable pylon scheme. The findings reveal that the open corbel structure bridge pylon exhibits lower transverse bending moment values under the influence of permanent load, vehicle load, temperature load, and wind load. This reduction is advantageous for mitigating the issue of significant temperature-induced secondary internal forces in the bridge pylon. Additionally, the transverse bridge stiffness of the open lower corbel cable pylon scheme is found to be on par with that of the lower continuous beam cable pylon scheme. Moreover, topology optimization of the original corbel design is accomplished using the relative density method. The computational results demonstrate that the corbel’s stress and deformation under vertical loads meet code requirements. These research findings offer valuable insights for the design and construction of similar projects.

Finite-Element Analysis of Temperature Field and Effect on Steel-Concrete Composite Pylon of Cable-Stayed Bridge without Backstays

The backless cable-stayed bridge has the advantages of beautiful shape and reasonable force, but due to the low overall stiffness of the bridge pylon during cantilever construction, it is susceptible to the effect of solar temperature. To reveal the temperature deformation laws and achieve accurate alignment prediction during the installation process of steel–concrete composite pylons in complex environments, a refined numerical simulation model for the 3D bridge temperature field was established based on the proposed automatic sunshine-shadow recognition method. Subsequently, the optimal time periods for construction control are provided. The results of the study show that, during the cantilever construction of the bridge pylon, one pylon column will shade the other pylon column, resulting in asynchronous deformation that can reach 7.6 mm. The effect of solar temperature on the displacement of the bridge pylon is significant, where the maximum daily change in transverse displacement in the cantilevered state of the pylon can reach 33.6 mm, and the maximum change in cable force value can reach 52 kN. In order to mitigate the effect of solar radiation, the best construction time for the bridge pylon is 19:30~9:30, while the tensioning and measurement of the cable should be avoided from 6:00~18:00. This strategy ensures that the control of the pylon top displacement is maintained within 1/4000 of the pylon height, and the error in cable force is kept within 5%.

Model Optimization of Ice Melting of Bridge Pylon Crossbeams with Built-In Carbon Fiber Electric Heating

This paper aims to improve the deicing performance and energy utilization of bridge pylon crossbeams with built-in carbon fiber electric heating (BPB–CFEH). Therefore, a three-dimensional thermal transfer model of BPB–CFEH with one arrangement is established. Two ice-melting regions and two ice-melting stages were set up according to the characteristics of the icing of the crossbeam. The effects of wind speed and ambient temperature on the paving power required to reach the complete melting of the icicles within 8 h were analyzed. The effects of the laying spacing and rated voltage of the carbon fiber heating cable on the melting ice sheet and the thermal exchange of the two regions of the icicle after heating for 8 h were compared. Additionally, its effect on energy utilization of the process from the ice sheet melting stage to the ice column melting stage was analyzed. Ice-melting experiments verified the applicability and reasonableness of the simulated ice-melting calculation formula. The results show that under ambient temperature of −10 °C and wind speed of 4.5–13.5 m/s, the proposed paving power is 817.5–2248.12 W/m2. Increasing the rated voltage and shortening the spacing increases the thermal exchange capacity of the two melting regions. The shortening of the spacing improves the energy utilization rate of the melting stage of the ice sheet to the melting stage of the icicle processes. The difference between the melting time obtained from the formula proposed by numerical simulation and the melting time obtained from indoor tests is about 10 min. This study provides a design basis for the electrothermal ice melting of bridge pylon crossbeams.

Fire Effect and Performance of Bridge Pylon Columns under Construction

The fire effect and performance of bridge pylons under construction were investigated via an analysis conducted on two types of pylons with different wall thicknesses. Three fire scenarios, namely internal fire, external ring fire, and external side fire, were established for a 40 m high section of the bridge pylon under construction. The distribution of fire smoke and temperature was obtained using fire dynamics simulation software for different fire scenarios. In addition, a finite element simulation was performed using the thermal–mechanical coupling method to obtain the temperature, stress, and deformation of the columns. The simulation results demonstrate that the average temperature of the internal fire is higher. The chimney effect extends the height range of temperature influence. In the vertical direction, the temperature decrease curve for the internal fire follows a single negative exponential function, while the external fire adheres to a double negative exponential function. The thickness of the temperature influence in the bridge pylon is extended by heating to approximately 200 mm. The stress value considering the thermal expansion coefficient is nearly 27.5 times that without the expansion coefficient, while the deformation value increases by 1 to 8 times. In conclusion, the calculations of the coupled expansion coefficient are helpful in improving the fire safety of bridge pylons.

Research on hydration-caused thermal cracking risk of steel-concrete composite bridge pylons

Due to the large volume and different material of composite bridge pylons, a significant cracking risk has not yet been verified during concrete hydration. To clarify the hydration-caused temperature characteristics of concrete in composite pylons, based on an actual cable-stayed bridge, a 3D thermal-mechanical coupling model was established, demonstrating a good agreement between the FEM and measurements. On this basis, the temperature field and effects of pylon segments were analyzed. The key parameters influencing the temperature field, including the pouring sequences, hydration heat release, cement content, initial temperature, and convective coefficient，were analyzed. Results indicate that the temperature evolution can be divided into three stages: rapid warming, sharp cooling, and fluctuation. The temperature distributions exhibit high inside, low outside, and single-peak along the thickness direction. During the hydration process, the growth rate of the concrete elastic modulus is higher than its tensile strength. The maximum stress of concrete is 5 MPa, considerably higher than its tensile strength, leading to a significant cracking risk. Additionally, the maximum stress of the steel shell reaches 50 MPa. Adjusting the constructional parameters and environmental effects are the most effective improvement measure. The cracking risk of concrete can be reduced by 20% and 25% for every 20 kg/m3 and 50 kJ/kg reduction in the cement content and the cement heat release, respectively. Furthermore, reasonable methods for reducing unfavorable thermal effects are provided, which can facilitate the rational design and construction of composite bridge pylons.

Fuzhou–Xiamen high-speed railway: a new paradigm for China’s cross-sea railways

The new 277 km Fuzhou–Xiamen high-speed railway in China is the country’s first cross-sea railway designed for operational speeds of 350 km/h. Completed in 2023, it involved various advanced construction technologies, including the world’s first 1000 t bridge-building machine to be used offshore, advanced corrosion-resistant steel, pioneering rotation of a main bridge pylon, and aerodynamic steel–concrete composite bridge decks with ballastless tracks. The innovative project represents a milestone for China’s high-speed railway, heralding a new era of cross-sea transportation.

Eccentric compressive behavior of PBL-stiffened double-skin composite walls in bridge pylons

Double-skin composite walls (DSCWs) stiffened with perfobond ribs (PBLs) have gained popularity for use in large-scale structures. This investigation aims to provide valuable insights into the performance of PBL-stiffened DSCWs when subjected to eccentric compressive loads. An experimental investigation was conducted on eight PBL-stiffened DSCWs. The failure modes, local buckling behavior, load-deflection behavior, moment–curvature relationship, and strain distribution were analyzed. The results indicate that an increase in the interval of longitudinal PBLs on the compressive zone of the DSCW specimens leads to a reduction in eccentric compressive resistance due to premature local buckling. However, the transverse PBL interval and removal of transverse rebars had negligible effects on the local buckling behavior of the faceplates and did not affect the resistance of the specimens. The ductility index of DSCWs slightly increased with an increase in concrete strength and was further enhanced by the presence of headed studs. The introduction of studs on the faceplates effectively delayed the onset of local buckling and improved the resistance of the DSCWs under eccentric loads. Throughout the loading process, the longitudinal strain remained almost linear, and the neutral axes remained unchanged, indicating that the plane section assumption works for PBL-stiffened DSCWs. To develop N–M interaction curves of PBL-stiffened DSCWs under eccentric loads, the effective area method was introduced to predict the post-buckling strength of unilaterally restrained PBL-stiffened plates. The proposed curves provided accurate and relatively conservative predictions of the experimental results due to the reasonable consideration of the local buckling effect.

Quantifying site-response effect of spatial variability earthquake on seismic failure mode of long-span sea-crossing cable-stayed bridges

Long-span cable-stayed bridge is a prevalent bridge type for sea-crossing passages and occupies an essential role in the transportation system. Non-uniform excitations significantly impact the response of long-span cable-stayed bridges, especially the site-response effect (ESR), which is one of the three primary characteristics. This paper employs a long-span sea-crossing cable-stayed bridge with consideration of hydrodynamic and pile-soil effects to systematically study the influence regularity and parameter sensitivity of the site parameter ωc on the response of critical components, and develop probabilistic seismic demand models between each component and ωc. The results reveal that the fragility of each component exhibits dissimilar sensitivities related to ωc, specifically, the changing amplitude of bearing fragility is greater than that of the bridge pylon. Consequently, when the soil type at the pylons changes from soft to solid, the damage sequence of the main pylon, pier and bearing has been changed, which exhibits different damage mechanism and failure mode. Furthermore, the mathematical model between the seismic parameters and damage mechanism is established to quantify the impact of ESR on the failure mode of sea-crossing cable-stayed bridges. Thus, it could provide a theoretical basis for the earthquake damage assessment and seismic optimization of long-span cable-stayed bridges.

Evaluation of Cable Tension Using Static and Dynamic Test on R.H. Fisabilillah Cable-Stayed Bridge, Batam-Indonesia

R.H. Bridge Fisabilillah (Bridge I) is a cable-stayed bridge, included in the series of Barelang Bridges (Batam-Rempang-Galang) which were built from 1992 to 1998. With the service life of the bridge reaching 25 years, it is necessary to check the health condition of the bridge structure. Bridge cables are one of the most important elements of a cable-stayed bridge. These cable elements dominantly experience tensile forces when transmitting loads from the decks to the bridge pylons. Cable force inspection methods can be carried out through the direct measurement method (e.g. static test using a lift-off method) and indirect measurement (e.g. dynamic test using accelerometer sensors, electromagnetic/EM sensors, and so on). This study aims to compare the cable tensile force based on the static test (lift-off method) in 2017 against the dynamic test (accelerometer sensors) in 2022. Evaluation of the cable tensile force based on the dynamic test was carried out using the taut string theory and beam string theory approaches. From the study, the two empirical approaches yielded insignificantly different results where a difference in the mean difference of -1,71% was found with a maximum difference of 28,15%. The study also shows an increase in cable force capacity to a maximum of 47,20% UTS (ultimate tensile strength) based on the taut string theory and a maximum of 53.37% UTS based on the beam string theory. This value is greater when compared to the results of the cable force based on the static test (lift-off) in 2017, which was a maximum of 41.64% UTS. It is recommended to carry out further and more comprehensive studies to determine the effect of changes in cable force distribution on the behavior of the structure on the R.H. Fisabilillah Bridge.

Enhancing the Dynamic Stability of Pylons via Their Drag and Lift Coefficients by Finite Volume Method

This study aimed to estimate the drag and lift coefficients of the long-span bridge pylon using the finite volume method (FVM). The k-ω turbulence model was applied to analyze the behavior of wind flow around the pylon, yielding drag and lift coefficient values with an error of 0.98% compared to a previous tunnel experiment. Four recommended cross-sections were proposed to reduce drag and lift forces acting on the pylon, including concave, convex, crossing, and chamfering cross-sections. The finding indicated that drag and lift coefficient decreased for all cross-sections. Cutting edges of concave, convex, and chamfering cross-sections with a ratio ranging from 0.2 to 0.3 has the greatest impact on reducing drag coefficient, while the crossing cross-section with a cutting ratio ranging from 0.2 to 0.25 has the lowest drag coefficient. The maximum reduction in drag and lift coefficients were 23.69% and 13.14% for concave and chamfering cross-sections. Thus, cutting edges of cross-sections is an effective method to enhance the aerodynamic stability of the pylon. Additionally, we evaluated drag and lift coefficients for different wind direction angles. The angles of 0, 30, and 90 degrees resulted in the highest drag coefficient, while the angle of 0 degrees and the angle of 90 degrees resulted in the lowest and highest lift coefficient, respectively. This study not only provides recommendations for cross-sections that reduce forces acting on the pylon but also provides the intensity of this reduction through corresponding estimation equations. In conclusion, concave and chamfering cross-sections are the most effective in reducing drag and lift coefficients, or, in other words, increasing the aerodynamic stability of the pylon.

Probability-based surface deterioration assessment of bridge pylon and state updating using inspected crack length distribution

This study presents a probability-based surface deterioration evaluation framework to evaluate the cracking damage of bridge pylons subjected to repetitive thermal stresses caused by daily temperature variations. First, a temperature prediction model for massive concrete bridge members was utilized, incorporating the effects of convection and radiation. Subsequently, the thermal loads applied to the bridge pylon were computed using the finite element (FE) method. A modified linear elastic fracture mechanics (LEFM) crack model combined with random field theory for predicting crack propagation in concrete was employed. A probability-based surface damage grade method for a bridge pylon was proposed. Moreover, the deterioration state evaluation was updated by incorporating Bayesian inference, which involved using in situ inspection results (i.e. spatial distribution associated with surface crack lengths). The methodology was implemented using an illustrative example that considers a bridge pylon. The results provide useful information for aiding decision-making strategies concerning the maintenance and repair of massive concrete bridge components.

Engineering of the National Namaste Signature Bridge Pylon

The National Namaste Signature Bridge in Delhi symbolically welcomes the world with the Indian welcoming pose, Namaste, its visual form having the emblem of a peacock’s feather on its main body. The very complex geometry of the 151 m high slanted steel pylon, meant to be twice the height of Qutub Minar supports a 575 m length deck having a cable-stayed span of 251 m, flanked by approach spans on either side of the main bridge. The steel composite deck integrated with the pylon is supported on spherical bearings having a capacity of 17,100 t, while eight backstays are anchored to specially designed pendulum bearings that can take an uplift of 6380 t, which in turn are anchored to a hybrid foundation of caissons and piles. The unprecedented nature of the design of the foundations, bearings and pylon called for ingenious and novel construction engineering and methodology to be evolved, whether for hybrid foundations, concrete technology, the erection of large capacity special type bearings, fabrication, trial assemblies, welding including very long and critical in situ welding of pylon base & finally segmental erection of three dimensionally varying pylon. In the paper while touching upon briefly the conception part of the other aspects like foundations, general arrangement etc., the detail deliberation on fabrication and segmental erection of three dimensionally varying pylon and steel girders has been made.

Refined 3D Solar Temperature Field and Effect Simulation of Ultra-High Steel Bridge Pylon

In order to accurately calculate the sunshine-induced temperature effect of an ultra-high bridge pylon, a refined numerical simulation model for the 3D bridge temperature field was established based on the proposed automatic sunshine shadow recognition method and pylon-height-related convection modification method. A suspension bridge H-shaped pylon with a height of 280 m was taken as an example, and the temperature field and corresponding thermal stress and deformation were calculated under typical meteorological conditions in spring, summer, autumn, and winter. The results show that the maximum temperature differences between the outer surfaces of the pylon can reach 19 °C and 16 °C for north–south walls and east–west walls, respectively, and exceed the recommended value of ±5 °C in the Chinese Specification. The maximum displacements can reach 370 mm and 110 mm at the top of the bridge pylon in the longitudinal and transverse directions of the bridge, respectively. After the modification of the convective coefficient of the outer surfaces with different wind speeds at different pylon heights, the temperature gradually decreased from the top to the bottom of the pylon, with a temperature difference of 8 °C. The significant influence of the sunshine shadow was shown on the temperature field and temperature effect of the bridge pylon. By considering the shadow effect, the maximum temperature difference can reach 12 °C between adjacent sunlit and shaded areas and can reach 14 °C between two pylon columns. A significant mutation of thermal stress existed in the shaded area, and the maximum stress could be reduced by 13 MPa compared with the adjacent sunlit area. Obvious asynchronous deformation was shown between two pylon columns, and the maximum asynchronous displacement at the top of the pylon can reach 18 mm and 45 mm in the longitudinal and transverse directions, respectively.

Tensile stiffness of perfobond rib connectors in steel–concrete composite pylon of bridges

Perfobond rib connectors (PBLs) are subjected to considerable tensile forces when used as stiffeners in steel panels and force-transfer structures in the cable anchorage zone in the steel–concrete composite pylons of cable-stayed bridges. Determining the elastic tensile stiffness of the PBLs is necessary for a structural analysis of the composite pylons. This investigation aimed to explore the critical parameters affecting the elastic tensile stiffness of PBLs and propose equations for accurately predicting the tensile stiffness of PBLs. Twelve PBL specimens were tested under pull-out load to investigate their elastic tensile stiffness. Thereafter, a parametric analysis was conducted via the finite element approach to examine the influence of the geometric characteristics of the perforated rib, transverse rebar diameter, and concrete strength on the tensile stiffness of the PBL. The results demonstrated that the elastic tensile stiffness of PBLs increased with the increase in the rib thickness, hole diameter, and concrete strength but decreased with increasing embedded depth. The perforated rib width had no influence on the elastic tensile stiffness. Additionally, the elastic tensile stiffness increased slightly as the transverse rebar diameter increased. Subsequently, a theoretical spring model was developed to predict the elastic tensile stiffness of the PBLs, considering the contribution of perforated ribs and concrete dowels. Finally, a comparative analysis was performed, which proved that the proposed equations in the present study based on the spring model were accurate in predicting the tensile stiffness of PBLs. The proposed equations are recommended for application in the structural analysis of composite pylons.

Model Experimental Study on De-Icing Method of Bridge Pylon Beam Based on Electric Heating

The icing of bridge pylon crossbeams is a problem that could pose a serious threat to traffic during a cold winter. However, little research has been carried out on the problem and few corresponding countermeasures have been provided. This paper aims to propose a novel heating system, and to study the feasibility of beam de-icing and the related de-icing strategies so as to provide a reference scheme for the practical application of beam de-icing. A number of icing and de-icing tests were carried out on a scale model of Wuhan Yangtze River Second Bridge in the cold chamber. The de-icing effects of the beam in different environments and different de-icing methods were compared, and the recommended pre-heating time, applicable environment range, and heating method were given. The results of the model experiments show that pre-heating the heating system can prevent the surface of the beam from freezing and that the anti-icing method is more suitable for beam de-icing than the passive de-icing method. When the pre-heating time exceeds 7 min, the entire anti-icing process can be ice-free. When the wind velocity exceeds 5 m/s, it is safer to shut down the heating system, and using the passive de-icing method at the end of the icing can also eliminate the hidden danger of beam icing.

Mechanical Behavior of Steel–Concrete Joint in a Bidirectional Curved Pylon of a Long-Span Cable-Stayed Bridge

The complex mechanical behavior of a steel–concrete joint (SCJ) in a bidirectional curved pylon of a cable-stayed bridge is investigated using finite-element analysis (FEA) and a 1:4 scaled full-section model test. Formulas for the stress distribution and stress nonuniformity coefficients of the concrete in the SCJ are proposed to evaluate the force transmission characteristic of the SCJ. The FEA results indicate that variations in the section stiffness at both the bearing plate and the end of the steel structure result in abrupt stress changes and distinct spatial force characteristics of the SCJ. The experimental results reveal that the SCJ exhibits better force resistance than the concrete and steel transition segments, and the force transfer is dominant through the bearing plate. The proposed formulas are validated by using the measured results, which reveal significant nonuniformity in the stress distribution. The stiffness variation at the bearing plate, nonuniform concrete stress distribution, and spatial force characteristics should be considered during the design of similar SCJs in spatial pylons.

Pull-out performance of perfobond rib connectors in steel high-strength concrete composite bridge pylons

Perfobond rib connectors (PBLs) used in steel high-strength concrete composite pylons of cable-bearing bridges are subjected to considerable pull-out forces caused by the local buckling tendency of the steel panels. In order to investigate the pull-out performance of PBLs embedded in high-strength concrete, an experimental study was conducted with twelve single-hole PBL specimens constructed of concrete with a cubic compressive strength of 80 MPa. The test results indicate that the failure of shallowly embedded PBLs was dominated by the concrete breakout. Then a numerical investigation was conducted using the validated finite element method to figure out the failure mechanism of the shallowly embedded PBLs, followed by a parametric study to identify the sensible parameters concerning the pull-out resistance. The numerical results show that increasing the embedded depth, concrete strength, and rib hole diameter can increase the pull-out resistance of the PBLs with an embedded depth smaller than 140 mm. In contrast, the thickness of perforated ribs exhibits a negligible impact on the pull-out resistance. It is recommended that the transverse rebar diameter should not exceed the difference between the rib hole diameter and the maximum coarse aggregate particle size of the concrete to avoid the possible decrease in the concrete strength near the rib hole. Finally, a concrete breakout model was developed to predict the pull-out resistance of PBLs shallowly embedded in high strength concrete with reasonable accuracy.