Temporary Pier Research Articles

Effects of Temporary Pier on Buffeting Response of a Three-Tower Cable-Stayed Bridge Under Construction

The wind-resistant performance of cable-stayed bridges under construction deteriorates sharply as the cantilever length increases, and the arrangement of the temporary pier is an effective measure to improve aerodynamic stability. To investigate the effect of the temporary pier on buffeting response of a long-span three-tower cable-stayed bridge under construction, the nonlinear buffeting analysis and wind tunnel test of aeroelastic model methods are adopted in this paper. The influence of the type and arrangement positions of temporary piers on mean wind response and the nonlinear buffeting response of double-cantilever construction are studied, and the arrangement of the temporary pier is optimized based on the buffeting response. The results show that the reduction rates of the RMS of the torsional moment at the tower bottom and the lateral buffeting displacement at the girder end with the rigid pier are 35.6% and 59.2% compared to those without the temporary pier. Further, the buffeting response will decrease as the distance between the rigid pier and the tower increases in the state. On the contrary, in the double-cantilever construction state before the constraint of temporary piers, the buffeting response will become significant as the distance increases. Therefore, it is necessary to consider the buffeting response under two construction states when optimizing the arrangement position of the temporary pier.

Three-Dimensional Numerical Simulation of the Water Flow Effect on a Temporary Pier with Three Columns in Series

In order to ensure the safety of temporary piers during bridge construction, it is necessary to analyze the water flow effects on temporary piers during flood periods. Based on the practical engineering of a new bridge in Jiangxi province, a three-dimensional numerical model was established using the Reynolds Time Average Navier–Stokes equation (RANS) and SST k-ω turbulence model to simulate the flow force on three-column temporary piers in series. The stress state of the temporary pier was obtained under different flow velocities and submergence depths. The distribution characteristics of the flow field around the temporary pier and the flow force characteristics acting on the temporary pier were analyzed and compared with the monitoring measurement data and the Morison equation calculation data. The results indicate that the local flow was accelerated on both sides of the temporary pier, but the local acceleration effect along the river flow direction was weakened. The flow velocity of the water around the temporary pier decreases with the increasing of river depth. The pressure on the outer surface of the temporary pier is basically negative pressure, except for the positive pressure on the upstream side. The absolute value of the negative pressure on both sides is much greater than the positive pressure on the upstream side. As the submergence depth and flow velocity increase, the pressure in each area gradually increases. The pressure distribution of the upstream pier is basically symmetrical, while the pressure distribution of the middle and downstream piers is asymmetric due to the influence of the vortex shedding from the front pier, resulting in a change in the water flow incidence point. The turbulence intensity in each region of the flow field shows a trend of first increasing and then decreasing with the depth of the water flow. The drag coefficient and lateral force coefficient of the temporary pier are basically not affected by the inflow velocity, but the resistance and lateral force increase with the increase in submergence depth and inflow velocity.

Measures to Improve Seismic Resistance by Fuse Mechanism in Pier Structures

AbstractIn Japan, temporary pier structures are designed to withstand earthquakes in consideration of their short service life, and seismic inputs exceeding the design are also expected. In order to confirm the deformation behavior of the fuse mechanism in this temporary pier structure, a fundamental study was conducted using a model specimen. The strength test results showed that the fuse mechanism behaved similar to a rigid body, and then the mortar fuse failed. After the failure of the mortar fuse, the reaction force was generated by the addition of the residual bearing capacity of the mortar fuse and the reaction force of the coil spring. The dynamic loading test results showed that the CFT columns contacted the remaining portion of the fuse after the mortar fuse ruptured, temporarily increasing the maximum response acceleration to 35 m/s2, but the response period became longer, indicating the deformation behavior of the fuse mechanism. In addition, the maximum load of the mortar fuse mechanism and the natural period after the mortar fuse rupture were calculated from the design values of the mortar fuse strength and the spring constant of the coil spring.

Flutter performance of a double-main-span suspension bridge during erection with temporary constraints on girders

An increasing number of double-main-span suspension bridges with three towers are now constructed. For this bridge type, close modes exhibits similar characteristics due to the participation of two main and side spans, which is more prominent during girder erection as different spans are disconnected. It is important but hard to accurately determine the modal combination for flutter analyses. In this paper, full-order modal flutter analyses were performed to study the flutter performance of a double-main-span suspension bridge during erection. The dominating modal branches for the anti-symmetrical and symmetrical flutter instability were determined, respectively. After that, temporary pier constraints on the side spans and temporary connections between girder segments were set, respectively, to study the flutter suppression. The results show that the anti-symmetrical flutter instability of the bridge during erection is prior to the symmetrical one except for the first two stages. Reinforcing the connections between girder segments in the lateral direction could significantly improve the anti-symmetrical flutter stability. Meanwhile, the symmetrical flutter instability of the bridge during erection is more complicated as it is associated with the girder torsion, cable swing, and girder lateral bending. The set of temporary pier constraints or proper temporary connections is favorable.

Aerodynamic loads and bridge responses under train passage: case study of an overpass steel box-girder cable-stayed bridge

Increased train speeds have led to significant train-induced wind problems. This paper describes a numerical study of the aerodynamic loads produced when a train passes under a bridge and the bridge dynamic response based on a steel box-girder cable-stayed bridge. The results indicate that the wind pressure on the bottom plate and the maximum lift on the beam sections increase as the train speed increases or as the clearance under the bridge decreases. Changes in the intersection angle are found to have a greater impact on the 1/4-span and 3/4-span regions. The effects of the various influencing factors are basically the same in the construction and operation stages. As the train speed increases or the clearance under the bridge decreases, the bridge responses exhibit an upward trend. As the intersection angle decreases, the vibration displacement tends to increase, but the effects on the vibration acceleration and maximum counter-force of the temporary pier are not consistent. Compared with the construction stage, the dynamic responses of the main girder are smaller in the operation stage due to the larger overall rigidity and the support constraints. In the parameter ranges investigated in this study, the absolute values of maximum vertical bridge vibration displacement and acceleration decrease from 4 to 16 mm and from 85 to 400 mm/s2, respectively, in the construction stage to 1–5 mm and 42–174 mm/s2 in the operation stage. Moreover, the counter-force falling on the temporary pier after the main girder turns does not exceed the 2000-kN positive force or 300-kN negative force limits. In the operation stage, the bridge vibration responses will not affect the comfort of pedestrians.

Research on the key technology of TIED-arch bridge Incremental Launching Method Construction

Steel tied arch bridge has been widely used in modern bridge construction due to its beautiful shape, high material utilization rate and overall structural stiffness. However, there are few cases in which the tied-arch bridge is constructed by incremental launching . Based on the steel tied arch bridge project, this paper uses finite element software to establish the finite element simulation analysis of the construction process, and monitors the construction process of the bridge. The test results show that it is in the most unfavorable state when the cantilever at the end of the bridge reaches the maximum. At this time, the stress at the 117 m position of the beam reaches the maximum, the stress at the top edge is 33.7 MPa, and the stress at the bottom edge is -58.2 MPa. The stress in other sections did not exceed 30 MPa, and the beam was under uniform stress. When the foot of the internal arch passes through the temporary pier, the supporting force of the pier is maximum, which is about 6000 kN. The reasonable range of α is between 0.55 and 0.65, which is the ratio between the length Ln of launching nose and the maximum span L of incremental launching .

Innovative Structure Design and Construction—Jiubao Bridge, China

Jiubao Bridge in Hangzhou has been built across the Qiantang River and has a length of 1855 m; it is the first large river crossing project in China using a completely composite structure. The main navigation and approach spans use the continuous hybrid arch-girder structure and steel–concrete continuous composite box girder, respectively; for both, the multi-point simultaneously incremental launching construction method has been used. Also, during the incremental launching construction, the 85 m approach span composite girder bridge was designed to have no temporary pier and only one temporary pier was considered for the 210 m main arch span. The design scheme of this bridge presents a new design philosophy, technology and creativity.

Nonlinear Stability Analysis of a Composite Girder Cable-Stayed Bridge with Three Pylons during Construction

Based on the nonlinear stability analysis method, the 3D nonlinear finite element model of a composite girder cable-stayed bridge with three pylons is established to research the effect of factors including geometric nonlinearity, material nonlinearity, static wind load, and unbalanced construction load on the structural stability during construction. Besides, the structural nonlinear stability in different construction schemes and the determination of temporary pier position are also studied. The nonlinear stability safety factors are calculated to demonstrate the rationality and safety of construction schemes. The results show that the nonlinear stability safety factors of this bridge during construction meet the design requirement and the minimum value occurs in the maximum double cantilever stage. Besides, the nonlinear stability of the structure in the side of edge-pylon meets the design requirement in the two construction schemes. Furthermore, the temporary pier can improve the structure stability, effectively, and the actual position is reasonable. In addition, the local buckling of steel girder occurs earlier than overall instability under load in some cable tension stages. Finally, static wind load and the unbalanced construction load should be considered in the stability analysis for the adverse impact.

Construction Scheme Research of Long-Span Cable-Stayed Bridge with Three Pylons Based on Structure Stability

This paper took the Wuhan Erqi Yangtze River Bridge as an example, using MIDAS software to simulate the working procedure of cantilever construction, and established the finite element model of composite girder cable-stayed bridge with three pylons during construction stage. Based on the first kind stability theory, this paper researched the influence of the different construction scheme, the setting of temporary pier, temperature load, and unbalanced construction load on the structure stability of composite girder cable-stayed bridge with three pylons so as to obtain the linear elastic stability safety coefficients of structure during construction stage, and then provided the theoretical explanation to the reasonable construction scheme and safety construction. The results showed that for the Wuhan Erqi Yangtze River Bridge, its linear elastic stability safety coefficients of structure during construction stage have met the code requirement. Besides, the buckling mode changed from the longitudinal buckling of pylon to combined instability of pylon and girder. Furthermore, the setting of temporary pier was reasonable, which effectively improved the linear elastic stability safety coefficients. Finally, temperature load and unbalanced load in construction reduced the linear elastic stability safety coefficients.

Pre-Camber Study on the Steel-Concrete Composite Beam Constructed by the Incremental Launching Method

This paper summarized and evaluated the girder construction methods of self-anchored suspension bridge, pointed out that the main beam linear would have a local depression between the largest span temporary pier when the steel-concrete composite beams were constructed by the incremental launching construction method, even if the main beam were withstand uniform bar-forces, moreover, the pre-camber curve of the main-girder could not arranged as a circle curve or quadratic parabola within the entire span. In view of this, the entire construction process of a self-anchored suspension bridge was analyzed by the finite element method, The results showed that the section property changes of the steel-concrete composite beam were the nature reason of the local depression on the main beam linear; The completed main beam was simplified into a three-span continuous beam which suffered vertical uniform distributing load and horizontal forces at the two ends, and the simplified formulas of calculating the vertical displacement of each span were derived by the force method; The numerical example showed that, the proposed simplified formulas could effectively solve the affection by the section property changes, accurately predicted the main beam cumulative vertical displacement, and the calculation accuracy could meet the engineering requirements, the conclusions of this paper had a strong guiding significance and reference value on the camber design and construction of the bridge wth the similar structural type.

Reasonable Elevation Calculation of Temporary Pier of Long-Span Steel Trussed Arch Bridges with Semi-Cantilever

When the scaffold construction method is applied on long-span steel trussed arch bridges, reasonable setting of the temporary pier elevation has significant influence on assembly linearis and safety assembly of long-span steel trussed arch bridges with semi-cantilever. In this paper, in accordance with the manufacturing linearis steel trussed beam bridge and steel truss beam linearis changing during building process, the calculation of temporary pier elevation was studied systematically, and practical function was deduced. Then, the method was applied to a long-span steel trussed arch bridge. The obtained result by in-situ assembly and dismantling presents that: 50 mm preserved method is considered in this paper, which can provide convenience for removing the temporary pier. At the same time, the rationality and reliability of the presented approach are verified. It also can provide reference for similar bridge construction.

Key Techniques of Integral Lifting of Steel Tube Arch for Zhuzhou Bridge in Baise

Superstructure of Zhuzhou Bridge in Baise is a combined system with strong beam and weak arch. It is combined by concrete arches of continuous rigid frame-steel tube. The construction sequence is first the beam then arch, finally the temporary pier is demolished to form the combined system. The middle three parts of steel tube arch rib in the middle span were assembled to a large unity, and it was integrally lifted by synchronous system of hoisting jack to reach positive stop. The techniques have the characteristics of fast, safe and low cost.

Key Technologies of Whole Incremental Launching Construction Control for Inclined Continuous Box Girder with Steep Longitudinal Gradient

Under the background of Liuyang River Bridge, systematical studies of the key technologies of incremental launching control for inclined continuous box-beam bridge are of important theoretical significance and practical engineering value, with the features of incremental launching construction control difficulties caused by vertical curve, skew, steep longitudinal gradient, and with cantilever flange and heavy box girder. The results show that the limitation of dead weight of box girder can be overcome by precast supporting system composed of box-girder precast bearing system and box-girder incremental launching bearing system. The factors of stiffness and weight of main girder should be considered for guiding beam configuration in incremental launching construction, which should choose reasonable stiffness, length and weight, to assure that the negative moment peak of largest cantilever status and a status when guiding beam is on the pier is consistent with the largest fulcrum negative moment during the use state. The predictive value and measured value of stress and deformation of whole process of steep longitudinal gradient incremental launching about inclined continuous box beam are in good agreement. Horizontal traction force of jack, transverse offset of box beam and stress of temporary pier are all be well controlled, satisfying all design requirements, which means that simulation analysis and control of whole process of incremental launching is effective and feasible. The study results offer reference for similar bridges about the whole process of incremental launching construction.

Patch loading and improved measures of incremental launching of steel box girder

Yandangshan Bridge is a tied-arch bridge of double-line railway with a (90 + 90) m continuous steel box girder and passes over a very busy highway in China. The incremental launching of the steel box girder of this bridge is a challenge for bridge builders, mainly because of the patch loading caused by large self-weight, large camber, unsymmetrical and flexible temporary transverse beams. Due to on-site working conditions, many commonly used measures cannot be taken for the launching of this bridge. The launching process is simulated using finite element method. The results have shown that significant local stress concentration would occur in the web plate and bottom plate of the girder if no improved measures are applied. The influencing factors of the stress concentration are studied. Four measures to reduce the local stress of the girder are presented and put into practice: to add two slide shoes on every pier; weld six short launching noses at the diaphragm of leading end of the box girder; pre-lift the 6 slide shoes on one temporary pier at different positions to eliminate part of the deflection of the temporary transverse beams, and use special adjustable slide shoes in one span. The whole launching process has been monitored and the measured stress and deformation coincide with the results of finite element analysis. Good effects have been obtained by applying the four improved measures. The incremental launching of the steel box girder of Yandangshan Bridge has been successful.

Viaduct over the Nalón River in Spain – A new experience with ‘strict box’ composite bridges

AbstractThe motorway viaduct over the Nalón River is 1100 m long and 27 m wide. The longitudinal structural system consists of a single strict composite box that takes advantage of the different properties of structural steel and concrete, going beyond the double composite action systems already in use for a long time. The box girder is enlarged by means of composite trusses connected to the upper slab at both sides of the deck. Longitudinally, the structure can be divided into two sections:– a 660 m long curving approach section over the river plain– a 440 m long straight section crossing the riverbed. The central part of this section is a 124 m span rigid frame composed of a box girder with varying depth and two elegant piers, one on each side of the river.The bridge was constructed by launching from both abutments. The launching of the main section, due to the varying depth of the box girder in the main span, required longitudinal auxiliary elements in order to launch it in the same way as the spans of constant depth. A temporary pier was built in the middle of the river in order to reduce the cantilever in the main span to a moderate length. The viaduct construction was completed in May 2007.

Flutter and buffeting performances of Third Nanjing Bridge over Yangtze River under yaw wind via aeroelastic model test

Third Nanjing Bridge over Yangtze River in China is a long-span steel cable-stayed bridge with a main span of 648 m and a closed streamline cross-section of single box. The flutter and buffeting performances of the bridge under yaw winds were investigated via a wind tunnel test of full bridge aeroelastic model at a geometric scale of 1:120. The service state and three key construction states including the longest single-cantilever state, the longest double-cantilever state with a temporary pier, and the longest double-cantilever state without any temporary pier, were considered in the test. The test was conducted in both smooth and simulated boundary layer wind fields with various combinations of wind yaw angle and inclination angle. The model was elaborately designed and manufactured, and the modal properties of the service-state model were checked before the test. The natural frequencies and mode shapes were identified automatically using a self-developed special software from the acceleration signals recorded in an ambient vibration test, where an “artificial” turbulent wind with lower mean speed of 1 m/s was used as a major ambient excitation addition to the “natural” one from the slight ground trembling. The modal damping ratios were checked using free-decay vibration approach. The testing results show that the bridge has enough aerodynamic stability for all structural states and wind directions concerned, and the most unfavorable buffeting responses often occur in yaw wind case with a yaw angle between 5° and 30°.

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