Main Pier Research Articles

Research on Monitoring Technology for Frame Piers of Continuous Box-Girder Bridges Constructed by the Cantilever Method

This paper focuses on the analysis of the stress state of a large-span frame pier-continuous box girder bridge with pier crossbeams anchored by pier crossbeams on the main pier of the Guangfo-Zhao Expressway. The bridge is constructed by the cantilever method, and a refined finite element model of the entire bridge is established using the finite element software Midas/FEA to analyze the stress state of the frame pier during the cantilever construction process. It is found that under the possible combined action of an unbalanced load during construction, the torsional resistance of the frame pier crossbeam does not meet the requirements of the design code. In order to eliminate the torsion of the frame piers, counterweights were used to monitor the frame piers during the construction of the box girders. In this paper, the theoretical calculation formula of the inclination angle of the end section of the frame pier crossbeam with the change of unbalanced bending moment, the calculation formula of the relationship between the horizontal displacement of the frame pier and the unbalanced bending moment, and the calculation formula corresponding to the relationship with the water tank counterweight are derived using the structural mechanics method. Two monitoring methods for the frame pier are proposed. In the construction monitoring of the bridge, the numerical fitting formula obtained by finite element numerical analysis calculation is compared with the calculated formula obtained by substituting the design parameters of the frame pier into the theoretical formula. The basic constants in both formulas are basically equal, verifying the correctness of the monitoring calculation formula proposed in this paper for the torsional resistance of the frame pier crossbeam. The applicability of the two monitoring methods is also compared and analyzed. This paper takes the main pier of Chaoyang overpass’s mainline bridge as the engineering background, which adopts the framework pier with a large-span prestressed concrete continuous box girder bridge. It analyzes the torsional state of the beam of the framework pier during the bridge construction process and conducts research on the construction monitoring of the framework pier crossbeam, providing valuable references for the construction monitoring of framework pier crossbeams in the construction of large-span framework pier continuous bridges in the future. The research results of this paper can provide assistance for the construction monitoring of similar projects. This paper’s innovation primarily resides in employing structural mechanics methods to compute the torsion of frame piers. On this basis, a simplified beam torsion calculation formula is proposed to strengthen its practical application in construction monitoring. The findings of this paper can help in the construction monitoring of similar projects.

Self-Centering Precast Unit as Energy Dissipation Members in Precast Segmental Bridge Columns

This research aims to present a new generation of seismic-resisting systems designed for precast reinforced concrete (RC) bridge piers in modern sustainable cities to withstand moderate to high seismic activity. The proposed system consists of two self-centering (SC) systems operating in parallel to bring together all features of the required resiliency during a seismic action. The first/main system is a hollow core precast segmental bridge column, and the second is composed of an SC precast unit and energy dissipation (ED) steel reinforcements positioned in the main pier segment’s hollow core. To study the performance of the proposed system, a finite element model was first developed to capture the behavior of experimentally tested precast bridge columns. After validation, the created model was systematically studied to investigate the performance of the entire proposed system under cyclic loading. The effects of three parameters related to the ED system were investigated, including the reinforcement ratio, the unbonded length of ED bars, and the SC post-tensioned force ratio. Furthermore, the impact of FRP wrapping on the lower part of the core column of the ED system was also investigated. An analytical model predicting the characteristic points of the lateral response of the proposed system based on the superposition concept is also proposed. The FE results showed that the entire proposed system is a new design-based resilient system with the ability to dissipate energy without compromising the SC capacity of the main resisting system. Compared to the typical precast hollow core segmental column, a 6% reinforcement ratio of the ED unit can cause a 60% increase in lateral resistance and a 220% increase in the ED capacity. The analytical model can successfully be applied in the design of the proposed system to provide customized ED capabilities and controlled lateral resistance.

Impact dynamics analyses on an innovative fiber-reinforced rubber composite bumper system for bridge protection

To reduce damage resulting from ship collisions and protect the bridge, an innovative fiber-reinforced rubber composite bumper system consisting of a steel box and a soft body is introduced in this study. Three specimens with different impact speed of the cart and the spacing of the steel box web were tested. These tests were carried out using scaled models to obtain impact force-time history curves. Subsequently, the collision failure modes were analyzed. Analysis results reveal that these anti-collision facilities not only have the capacity to reduce damage to ships but also protect the bridge's pier. Furthermore, the energy absorption behavior of the system was examined. To further test the practicality of the approach, the main piers of an actual-sized cable-stayed bridge were equipped with fiber-reinforced rubber composite bumper systems for collision simulation. In simulations of ship-bridge collisions, cases with and without anti-collision facilities were compared. A decrease in the peak impact force and an extension of the impact process when using the fiber-reinforced rubber composite bumper system were found. Its effectiveness in safeguarding both ships and bridge piers is highlighted. Additionally, a parameter study on velocity was conducted, demonstrating the system's ability to withstand higher energy impacts. Furthermore, it was found that changes in stiffener and soft layer thickness can influence the impact force response.

Hydration Heat Control of Mass Concrete by Pipe Cooling Method and On-Site Monitoring-Based Influence Analysis of Temperature for a Steel Box Arch Bridge Construction

The steel box arch bridge in this study will be subjected to various temperature effects from the construction to the operation stage, including the cement hydration heat effect and the sunshine temperature effect caused by an ambient temperature change. Therefore, it is very important to control the temperature effect of steel box arch bridges. In this study, the newly built Dafeng River Bridge is selected as the steel box arch bridge. This study aims to investigate the temperature effect including hydration heat and the sunshine temperature effect of the construction process of a rigid frame-tied steel box arch bridge. The manuscript presents that the heat dissipation performance of concrete decreases with the increase in the thickness of a mass concrete structure. The average maximum temperature values of layer No. 3 are about 1.3, 1.2, and 1.1 times the average maximum temperature value of layer No. 1 for the mass concrete of the cushion cap, main pier and arch abutment, respectively. The higher the molding temperature is, the higher the maximum temperature by the hydration heat effect is. With each 5 °C increase in the molding temperature, the maximum temperature at the core area increases by about 4~5 °C for the mass concrete. The pipe cooling method is conducive to the hydration heat control effect of mass concrete. Based on the monitored temperature change and displacement change, the influences of daily temperature change on the steel lattice beam and arch rib are analyzed. A temperature rise will cause the structure to have a certain camber in the longitudinal direction, and the longitudinal or transverse displacement caused by the sunshine temperature change is no less than the vertical displacement. Due to the symmetrical construction on both sides of the river, the arch rib deformation on both sides presents symmetrical synchronous changes. Based on 84 h of continuous temperature monitoring on-site, the changing trends of the arch back temperature and ambient temperature are consistent and their difference is small during 1:00~4:00 in the morning, which is determined as the appropriate closure time for the newly built Dafeng River Bridge.

Seismic performance improvement of continuous rigid-frame bridges with hybrid control system under near-fault ground motions

To improve the seismic performance of continuous rigid-frame bridges (CRFBs) in near-fault earthquakes, this study developed a hybrid seismic control system (HSCS) combining a three-dimensional hybrid seismic isolation bearing (3D-HSIB) with a longitudinal fluid viscous damper (L-FVD). The hybrid numerical model of the HSCS and the nonlinear numerical model of a CRFB prototype were simulated in OpenSees. The study comparatively analyzed the seismic responses of non-controlled bridges and HSCS-controlled bridges under near-fault ground motions, evaluated the seismic control effectiveness of the HSCS, and investigated the effects of vertical excitations on the seismic performance of the CRFB. The numerical results show that the proposed HSCS effectively reduces the three-directional seismic responses of the CRFB. When the PGA is 0.4 g, the seismic isolation ratios of displacement, internal force, and pounding force all exceed 0.4. The hysteresis behavior of the HSCS can be fully utilized under three-directional excitations with pulse-like effects. The girder-end uplift behavior under vertical excitation can be effectively controlled by the proposed 3D-HSIB with a seismic isolation ratio of at least 0.6. When vertical excitation exceeds a certain level, the bearing is tensioned upward while axial tension force may also occur in main piers. Furthermore, the seismic responses under pulse-like near-fault ground motions are significantly larger than those under non-pulse near-fault ground motions. This work may provide a useful reference for the seismic analysis and design of CRFBs.

Seismic Responses and Damage Control of Long-Span Continuous Rigid-Frame Bridges Considering the Longitudinal Pounding Effect under Strong Ground Motions

Continuous rigid-frame bridge (CRFB), a type of bridge adopting the unique form of pier-girder consolidation, combines a T-shaped rigid frame with a continuous girder. CRFBs located in western China are likely to suffer destructive earthquakes, which may result in serious damage to bridges. To study the longitudinal seismic responses and damage control of different structure types of the CRFB under strong ground motions, this work develops three nonlinear dynamic analysis models considering the initial internal force state and longitudinal girder-pier pounding effect based on the OpenSEES (version 3.3.0) platform. Moreover, the present study comparatively analyzes the displacement responses, internal force of piers, pounding force and times, and damage condition of the three models and investigates the effectiveness of tuned inerter-based dampers (TIBDs) in controlling seismic responses of the CRFB. The numerical results show that the longitudinal seismic responses of the main piers in the three models are obviously different, especially when subjected to near-fault ground motions. The peak pounding force at the abutments is much larger than at the transition piers, while the pounding times are the opposite. Under near-fault ground motions with a peak ground acceleration (PGA) of 0.4g, the main piers may be damaged moderately or even more seriously, and the bearings are completely destructive. The TIBDs can effectively control the maximum seismic responses and damage degree of the CRFB under pulse-like near-fault ground motions. Among them, both the tuned viscous mass damper and tuned inerter damper are ideal and useful devices. This study can provide useful references for the seismic design and performance analysis of CRFBs.

Dynamic responses and residual capacity of high-strength CFST members subjected to axial impact

Impact is one of the main accidental actions that should be considered; high-strength concrete-filled steel tubular (HSCFST) members are mainly served as the main piers of high-rise buildings, large-span bridges, and defense structures. Hence, this study systematically investigated dynamic responses and residual capacity of HSCFST members subjected to axial impact. A total of six square HSCFST columns were tested, including testing groups with high-strength steel Q690 and a control group using normal-strength steel Q355. Results showed that as the impact energy increased, the local buckling of the steel tube became more severe, and the impact force, time duration, maximum axial displacement, and residual deformation were also enlarged; the residual capacity and residual rate were reduced. High-strength steel significantly improves the axial impact resistance and residual capacity. However, the increment of residual capacity by using high-strength steel was relatively small owing to the severe local buckling of steel tubes. Furthermore, the application range of developed equations for predicting maximum displacement of CFST members subjected to axial impact has been extended to high-strength steels (i.e., up to Q690), and together with the axial displacement limits (i.e., 1/100 L), these equations can be employed as a simplified method for anti-impact design.

Inclination prediction of a giant open caisson during the sinking process using various machine learning algorithms

Machine learning (ML) models based on 12 ML algorithms were established to predict the open caisson inclination. The prediction performance of these models was evaluated in the main pier open caisson monitoring of the Changtai Yangtze River Bridge Project, and the prediction performance was compared based on prediction results, corresponding residuals, prediction accuracy, calculation time and training sample dependence to determine the suitable prediction models. Then, the influence of 3 key parameters was analysed, and the models with the best prediction performance were optimized. The results showed that 7 ML algorithms were suitable for inclination prediction of this project. The best performance was obtained using models based on extra trees (XT) and k-nearest neighbour (KNN). The influence of the 3 key parameters on the prediction accuracy was determined, which is beneficial to further optimize the prediction models. After optimization, the root mean square error and the calculation time of the KNN model were decreased by 45% and 33%, and the best prediction accuracy was obtained using the default parameter settings of the XT model.

Reliability Analysis of the Main Pier during the Construction Period of HLCR Bridges

In the process of cradle construction for high-pier, long-span, continuous, rigid-frame (HLCR) bridges, the strength failure and instability damage of the main pier will directly affect the bridge construction safety. Therefore, it is necessary to study the reliability of the main pier during the construction of HLCR bridges. This paper starts from the factors that easily affect the stability of the main pier during HLCR bridge cradle construction, establishes the resistance and load probability model of the main pier during the maximum cantilever stage and the maximum unbalanced load of the continuous, rigid-frame bridge’s hanging cradles, fully considers the influence of random factors on the reliability of the pier, and calculates and analyzes the reliability index β through calculation examples. The results show that the changes of various random factors during the construction process have different degrees of influence on the reliability of the bridge pier. Our work provides a basis for the safe control of hanging cradles in the construction of HLCR bridges.

Impact of Near-Fault Ground Motions on Longitudinal Seismic Response of CHRF Bridges

Curved high-pier rigid frame bridges (CHRF bridges) are unavoidably affected by near-fault ground motions (NFGMs), and seismic pounding between adjacent components of CHRF bridge has a significant effect on the seismic performance of CHRF bridges. The seismic response and seismic pounding laws of CHRF bridges under NFGMs need further investigation. In this study, the influence of NFGMs with impulse and directional effects on the dynamic response of CHRF bridges was studied. Subsequently, the pounding responses between adjacent components of CHRF bridge were systematically analyzed. The results showed that the impulse and directional effects of NFGMs have a significant impact on the seismic response of CHRF bridges. The seismic response of CHRF bridges under near-fault impulse-like ground motions (IPGMs) is greater than that under near-fault non-pulse-like ground motions (NPGMs). CHRF bridges have the lowest seismic response under far-fault ground motions (FFGMs). The seismic response of CHRF bridges is significant under backward region ground motions (BRGMs) and the lowest under forward region ground motions (FRGMs). The IPGMs induce larger pounding force (PF) and a smaller number of poundings (PN) compared with FFGMs. The PF and the PN increase from the FRGMs to the BRGMs. Because of the pounding, the impulse and directional effects of NFGMs cause the shear force of the main pier and the auxiliary pier of CHRF bridges to increase significantly and the relative bending moment decreases. Moreover, the shear force and bending moment of the tie beam increases significantly owing to pounding.

A Hydraulic Analysis of Shock Wave Generation Mechanism on Flat Spillway Chutes through Physical Modeling

Shock waves are generated downstream of spillways during flood operations, which have adverse effects on spillway operations. This paper presents the physical model study of shock waves at the Mohmand Dam Spillway project, Pakistan. In this study, hydraulic analysis of shock waves was carried out to investigate its generation mechanism. Different experiments were performed to analyze the rooster tail on a flat spillway chute and to examine the factors affecting the characteristics of the rooster tail. The study results show that shock wave height is influenced by spillway chute slope, pier shape, and flow depth. Moreover, the height of the shock wave can be minimized by installing a semi-elliptical pier on the tail part of the main pier. Further modifications in the geometry of the extended tail part of the pier are recommended for the elimination of the shock wave. Based on observed data collected from the model study, an empirical equation was developed to estimate the shock wave height generated on the flat slope spillway chutes (5° to 10°).

Ship Impact Force Analysis and Design Project Selection of Pinghai Bridge

Based on summing up the domestic and foreign ship impact force calculation formula, the finite element method was used to establish the Pinghai Bridge analysis model. The pier ship impact force as a reference came from relevant design data, and the finite element calculation and analysis on ship impact were carried out. For there is auxiliary pier and not, the internal forces of main pier, cap bottom of main pier and a single pile under the combinations of ship impact force along and across the bridge direction of Pinghai Bridge were respectively calculated and reinforcement designed. The results show that the section of main pier can meet the force requirements only by the structural reinforcement; under the ship impact loads, saving the auxiliary pier has little effect on the results of section reinforcement of the main tower and the main pier. These conclusions have reference values to some extent for the design plan selection under the action of ship impact force.

Ecological Index of Fouling Organisms in Different Media In Daruba Morotai Island District

On the port pole is very much found biota attached. The biota is barnacles (Balanus sp). The attachment does not only occur in natural substrates. It may also occur in different means of human interest, such as ships and docks. This research is devoted to macroscopic biofouling, whose attachment is massif on the dock pole. This study aims to determine the species and ecological index of biota fouling in different media in the Daruba Morotai Island Regency. The data retrieval method uses a quadratic with a scale of 20×100 cm2. This study used three media, namely wood media (speedboat wooden pier), iron media (speedboat floating pier), and concrete media (Imam Lastori's main pier). Ecological indices analyzed include abundance, Diversity Index, Uniformity Index, and Dominance Index. The analysis results found the most number of macrobiofouling species in the wood medium (7 species). The largest number of individuals found is Branchidontes sp. (661 individuals). The findings of the study of the maximum macrofouling abundance are found in concrete media with a value of 491. Diversity in all media is classified as medium with a value of H' on wood media 1.22, iron media 1.04, and concrete media 1.34. The uniformity index (E) of all three media indicates the uniformity of broad populations with the maximum E found in concrete media 0.84. The study of dominance in wood media by 0.41, iron media 0.48, and concrete media 0.32 showed that dominance is poor.

Experimental study on the lateral distribution of the sidewall friction of large and deep-water caissons

The insufficiency of research on the calculation of the sidewall friction of large and deep-water caissons lies in that the longitudinal and lateral distribution of the sidewall friction is not clear. In this paper, a large-scale (1:70) model test was conducted based on the caisson foundation of the main pier at the Shanghai-Suzhou-Nantong Yangtze River Bridge to explore the longitudinal and lateral distribution of the sidewall friction during the dynamic and stable sinking process of caissons. The result shows that the sidewall friction along different longitudinal sections increases first and then decreases, with the peak value near the step. The lateral distribution of the sidewall friction is in the form of a parabola of “small in the middle and large at the ends.” On a cross section, the distance between the median point of friction and the midpoint of the section is about 0.3 times the side length. Also, this paper established a simplified four-segment model to calculate the sidewall friction of large and deep-water caissons.

Numerical Simulation Study on Cross Construction of Seawall Engineering and Bridge Foundation

In view of the overlapping project between the double track bridge of Ningbo-Taizhou-Wenzhou expressway and seawall, the large-scale three-dimensional finite element calculation is carried out by using the finite element software ABAQUS, the displacement limit of bridge pier top is studied, the internal force deformation of bridge pile foundation and its variation law in the process of seawall filling and later consolidation settlement are analyzed, and the influence of sea seawall filling on the stress and deformation of bridge pile foundation is studied. The calculation results show that: the main pier in the enclosure side of the two main piers in the design scheme is most affected by the construction of seawall. At the end of seawall construction, the longitudinal displacement along the bridge is 25.56cm, the transverse displacement is -10.68cm, and the settlement is 3.49cm. From the beginning of seawall construction to 15 years after the completion of seawall, the maximum longitudinal displacement along the bridge is -80.87cm, the maximum transverse displacement is -38.94cm, and the maximum settlement is 382.2cm, in which the settlement during the construction period is 346.0cm, accounting for 90.5%. The calculation results of design scheme show that the displacement of bridge pier top is too large, and the tensile stress of bridge pile is also large, therefore, it is necessary to optimize the design scheme to reduce the displacement of the bridge.

Study on Fatigue Strength of Main Anti-collision Structure of Main Pier

In order to improve the efficiency of water transport, avoid energy waste and protect the environment of the ocean and river, the protection of large transport vessels is particularly important. With the continuous development of waterway regulation and the continuous improvement of navigation conditions, the number of ships sailing in the Yinzhouhu section is increasing, and the risk of bridges being hit by ships is also gradually increasing. There are two common ways of bridge anti-collision: independent anti-collision system and its own anti-collision system. The former often adopts the form of independent anti-collision pier, which is generally used in the anti-collision area of old bridges, New bridges generally do not use this method, the latter mainly uses the method of improving the structural firmness of piers to achieve anti-collision, which is the most commonly used and more economical anti-collision method at present. In order to select a more reasonable standard of ship impact force and lay out reasonable anti-collision facilities, the anti-collision facilities of left branch main pier (55, 56) and right branch main pier (76, 77) of ZhongKai Yinzhouhu super-large bridge are studied and designed to provide reference for bridge design.

Experimental study of the wave load on the main pier of Huangmaohai Bridge under wave-current coupling effect

For the wave-current coupling effect on the main pier of Huangmaohai Bridge, experimental study is conducted to measure the load under wave-only and wave-and-current actions. Parametric studies are carried out to reveal the variation trend of the wave load with wave height and period. With the scouring depth of 12m and under the high-water level and wave height of 300-year return period, the maximum horizontal force FX on the pile cap is 13686.1kN, the maximum overturning moment MY is 260115.5kN·m, while the maximum horizontal force on the pile cluster is 13775.0kN. For the cap and cluster, the load caused by irregular wave is greater than that caused by regular wave. The load increases with increasing wave height and period. Under the wave-current coupling effect, the variation trend of the wave load is similar to that under wave-only conditions. The load on the cap decreases with the increase of scouring depth, due to the wave deformation in shallow water. The load on the pile cluster increases with the increasing scouring depth due to the greater exposure to the fluid environment.

Calculation of influence range of impact holing on the adjacent railway

In order to solve the impact of actual construction projects on the existing surrounding environment, the impact and vibration of the impact on the existing railway subgrade stability caused by the construction of the bridge foundation are analyzed. Based on the actual case of the construction project of No. 37 main pier across the Jiaoji Railway Main Bridge at Binlai expressway, the influence of the impact holing on the adjacent railway is analyzed. The influence range of the construction vibration is based on the Chinese Seismic Intensity Scale (GB/T 17742-2008) and Safety Regulations for Blasting (GB6722-2014), and taking the maximum velocity allowable value as criterion, the minimum safety range of impact drilling is obtained. Using the theory of small hole expansion to calculate the influence of the effect of soil compaction, the minimum allowable value of safe distance for the Construction technology of impact forming hole is considered 6.5m; in addition, based on the numerical simulation of nonlinear time history analysis, a reasonable exciting force parameter is given for practical engineering. The influence of impact amplitude A and impact frequency f on construction safety distance is analyzed. The results show that: The minimum safety distance of impact drilling is linear with the increase of impact amplitude A. When the impact frequency f is greater than 10Hz, the minimum safety distance tends to a fixed value as f increases. The results of this study guide the actual construction of the field, it guarantees the normal traffic of the Jiaoji Railway and provides a theoretical support for similar projects.

Construction Technology of Composite Cofferdam for Main Pier Bearing Platform of Dongjiang Lichuan Bridge

Dongjiang Lichuan Bridge in Dongguan City is a curved tower curved beam cable-stayed bridge with a main span of 138m and no back cable. The main pier cap is located on the bank slope of Dongguan Waterway on one side of Nandi Road. The cushion cap is dumbbell type, and the left and right cushion caps are connected by tie beams. In most areas, the top of rock stratum is above the bottom of bearing platform. The rock stratum within the buried depth of bearing platform is moderately to strongly weathered argillaceous siltstone. The geological conditions are complex and the construction is difficult. In line with the principles of speeding up the construction process and improving economic benefits, comprehensive analysis and weighing advantages and disadvantages, the main pier cap adopts a composite cofferdam of filling soil to build an island and combining bored pile rows and steel sheet piles. The construction task of bearing platform of main pier has been completed with high quality. Compared with other cushion cap construction methods, this construction method has the advantages of fast construction, high quality, simple safety, energy saving and environmental protection. This paper briefly introduces the design scheme of composite cofferdam, expounds in detail the operation steps of steel sheet pile construction and the problems needing attention in construction, and provides good reference experience for similar pile cap construction.

GEOMATICS IN BRIDGE STRUCTURAL HEALTH MONITORING, INTEGRATING TERRESTRIAL LASER SCANNING TECHNIQUES AND GEOTECHNICAL INSPECTIONS ON A HIGH VALUE CULTURAL HERITAGE

Abstract. The paper presents preliminary findings from a research study designed to assess the health status of a medieval bridge built on 1500 under the Medici dynasty over the river Sieve, close to Florence. The structure, a two span stone bridge with a main central pillar, experienced some restructuring interventions from 1555 to the present. The left span has been closed for some decades, and for many years the water has been allowed to float under it in case of severe flood only. At the beginning of year 2000 the left span has been opened to the regular flux of water. After opening, a maelstrom has been noticed as permanently present at the main pier’s basis highlighting the presence of a fracture in the concrete base around the central pile of the bridge. In order to investigate structural health and to assess bridge’s stability structural inspections and hydraulic surveys have been carried out. This manuscript reports Terrestrial Laser Scanning (TLS) survey results. Surface comparisons to identify anomalies and defromations have been carried out by exploiting Two TLS campaigns that were performed within a 6 years time span.