Continuous Prestressed Concrete Box Girder Research Articles

Construction monitoring of a long-span prestressed concrete continuous box girder bridge with variable sections

The structural behaviors in each construction stage were monitored and analyzed against the background of a long-span prestressed concrete continuous box girder bridge with spans of 55+100+55 m. At first, the formwork erection elevation and pre-camber of the bridge in each stage, as well as stress values of key cross-sections were determined by simulating the whole construction process using the finite element software. Then, the design parameters were identified and the model was corrected by field data collection and considering various influencing factors, so as to ensure effectiveness of the model. Finally, the formwork erection elevation was adjusted according to the stress and altitude in each construction stage, followed by closure of the bridge. According to field monitoring and adjustment, the measured alignment and stress of the bridge conform to the design and the error meets the requirements of specification, indicating a favorable monitoring effect. The research can provide reference for construction of similar bridges.

Analysis of continuous PC box girder bridges with CSWs by using equivalent computational model

The widespread usage of prestressed concrete (PC) box girder with corrugated steel webs (CSWs) can be attributed to its many remarkable merits over traditional concrete box girders, such as significantly reducing the deadweight of the girder, speeding up the construction process, avoiding the problem of web cracking and increasing the prestress introduction efficiency. Numerous previous studies were conducted to investigated the mechanical properties of CSWs as well as simply supported box girder bridges with CSWs, whereas very few studies focused on the FE modeling methods of continuous PC box girders with CSWs. In addition, experimental work on scale bridge models or full-scale bridges adopting the box girder with CSWs is very limited. In this paper, an equivalent orthotropic web (EOW) model was developed for CSWs and used to analyze the performance of the continuous PC box girder bridges with CSWs. To verify this model, a one-tenth-scale bridge model was developed for an existing continuous PC box girder bridge with CSWs. Both static and dynamic tests were carried out on this scale bridge model. The results obtained from the bridge finite element (FE) model with EOWs were compared to the results obtained from the bridge FE model with CSWs and also the experimental results from the scale bridge model. Good agreement was achieved between these results, indicating that the EOW model can provide a trustworthy and convenient tool in the FE analysis of PC continuous box girder bridges with CSWs.

STRESSING STATE ANALYSIS OF LARGE CURVATURE CONTINUOUS PRESTRESSED CONCRETE BOX-GIRDER BRIDGE MODEL

This paper experimentally analyzes the working behavior characteristics of a large-curvature continuous prestressed concrete box-girder (CPCBG) bridge model based on structural stressing state theory. First, the measured strain data is modeled as generalized strain energy density (GSED) to characterize the stressing state of the bridge model. Then, the Mann-Kendall (M-K) criterion is adopted to detect the stressing state leaps of the bridge model according to the natural law from quantitative change to qualitative change of a system, which derives the new definition of structural failure load. Correspondingly, the stressing state modes for the bridge model’s sections and internal forces are proposed to verify their changing characteristics and the coordinate working behavior around the characteristic loads. The analytical results reveal the working behavior characteristics of the bridge mode unseen in traditional structural analysis, which provides a new angle of view to conduct structural analysis and a reference to the improvement of design codes.

Experimental and Simulation Analysis of Prestressed Concrete Continuous Box Girder Bridge

Experimental and Simulation Analysis of Prestressed Concrete Continuous Box Girder Bridge

Research on Temperature Effects of the Pre-Stressed Concrete Box Girder Bridge

The distribution of the temperature gradient and temperature change of the pre-stressed concrete box girder are extremely complicated because of the multiplex environment. Temperature load has attached great importance in the field of engineering, and it has a great influence on the bridge’s structure, especially the box structure. The engineering background of this paper is a typical three-dimensional pre-stressed concrete continuous box girder bridge with variable cross section, comprising five spans in one continuous unit. Experiment on it and research the change rules of the temperature distribution, as well as the influence of the structure’s internal force resulted by temperature. Finite element software-Midas/FEA is used to model and calculate the bridge in order to analyze the temperature influence on structure’s stress in contrast to the measured data from the experiments

Study on the Shear Lag Effect of the PC Box Girder Bridge with Corrugated Steel Webs under Concentrated Loads

There are few studies about the shear lag effect and the effective flange width of the PC (Prestressed Concrete) box girder bridge with corrugated steel webs throughout the world in current time. In the present paper, based on the three-dimensional finite element analysis for a long-span continuous PC box girder bridge with corrugated steel webs and the corresponding conventional box girder bridge with concrete webs, a comparative study on the shear lag effect under vertical loads are carryied out together with the analyslis on the coefficient of the effective flange width. The results show that in the PC box girder with corrugated steel webs, the transverse distributions of longitudinal normal stress on the section of the slabs are obviousely non-uniform and they are different with those in the conventional PC box girder with concrete webs. And moreover, the shear lag effects in top slab of the PC box girder with corrugated steel webs are almost less obvious than those of the conventional PC box girder with concrete webs. However, the shear lag effects in bottom slab of the PC box girder with corrugated steel webs are almost similar to those of the conventional PC box girder with concrete webs, no matter what kind of vertical bending moment the cross section is subjected to

ABUTMENT-PILE-SOIL INTERACTION OF A PSC BRIDGE UNDER SEISMIC LOADING

The practical orientation of all the bridge structures are not straight, they may be skewed to some angles. A skewed bridge is one in which the major axis of the sub structure is not perpendicular to the longitudinal axis of the super structure.. The structural response of a skewed bridge to seismic loads gets significantly altered by the skew angles of the sub structure. Sub structure components consist of abutments, piers and foundations. These components always rest in the soil, hence the response of the structure caused by the flexibility of the foundation soil, as well as the response of the soils caused by the presence of the structure need to be assessed. Hence the study of soil structure interaction of sub structure (Interaction of Soil – Abutment - Pile) shows the behaviour of the sub structure and the soil due to seismic loadings. A Two span continuous prestressed concrete box girder bridge is selected as the super structure of the bridge and Finite element package SAP2000 V 14.2.4 software is used to model the bridge and to perform the analysis. The soil is modelled as five types of springs for which the spring stiffness are determined based on the guidelines given by American Petroleum Institute (API). These springs are modelled in SAP2000 as link elements. Earthquake record of the two major earthquakes Electro and Coalinga are collected from Pacific Earthquake Engineering Research (PEER). The input accelerations are scaled down to the acceleration of the Bangalore region and the time history analysis is performed. The super structure and the sub structure are modelled separately and the soil structure interaction is carried out. The response of the sub structure is obtained in the form of displacement, velocity, acceleration and spectral displacement, spectral velocity and spectral acceleration for the models with and without soil structure interaction.

Influence of Cracks Parameters on Bearing Capacity for Prestressed Concrete Box Girder

For long-span pre-stressed concrete continuous box girder bridges, cracks and other damage problem are often found because of influence of loads, climate, operations management and other factors during operation. The problem of cracking is serious increasingly, which has a direct impact on usability, durability and security. In order to analyze the bearing capacity of the bridge with cracks under different parameters, such as cracks width, cracks height and cracks spacing and provide the basis for the safety assessment and reinforcement, the paper puts forward the cracking reduction coefficient that evaluates the bearing capacity of the damaged bridge based on the tensile stress control. A three-span continuous rigid frame bridge is analyzed and the result shows that the bearing capacity of the bridge is in inverse proportion to cracks width and cracks height. The bearing capacity of the bridge is in direct proportion to cracks spacing.

The Posttensioning Method of Prestressed Concrete Continuous Box Girder Construction Technology

In this paper, prestressed concrete continuous box grider with prestressing method was introduced, including construction technology, construction methods, main construction equipment, the main materials and semifinished products and the dispose of main problems in the construction of the processing.

Application of a Grillage Model in Finite Element Analysis of Pre-Stressed Concrete Continuous Box-Girder

The grillage method is an analytical method of space structure which can simulate the original structure; it can get the deflection and strain data of main control section, to satisfy the calculation requirements of the static loading test theory for box-girder. This paper regards Tuanjie Road junction bridge static test of Daqing city as the research object, adopts finite element program ANSYS to emulate the test bridge, it mainly discuss influence degree to the loading of the curved girder bridge at the different load with longitudinal and transversal members of grillage by the different dividable method, its effectiveness is verified.

The Discussion on Deflected Pre-Stressed Tendons and Diagonal Cracks of Webs in PSC Box Girders

Abstract In order to find the relationship between deflected pre-stressed tendons and diagonal cracks of webs and provide basis to design and construction of bridges, a characteristics section model of a long span pre-stressed concrete continuous box girder, which is now under construction in Chongqing is analyzed by using nonlinear finite element program Midas-FEA. A numerical simulation analysis to the tensile stress in the webs was down based on the actual construction situation. As the research shows: 1, Stress concentration exists at the point where pre-stressed tendons are anchored, and the stress value was higher in anchorage area, which accord with the Saint-Venant Principle.2, The main tensile stress of webs in the anchorage area is lower than 1.04MPa, which did not surpass the standard 2.74MPa of the concrete tensile stress of C55, as a result, webs would not craze from finite element analysis. 3, Cracks brought by other normal or abnormal reasons existed in the process of casting the cantilever...

Effects Analysis of Web Cracks on Long-Term Deformation of Large Span Pre-Stressed Concrete Continuous Box Girder Bridge

Excessive deflection and its long-term sustainable development has become a common disease of large span pre-stressed concrete continuous box girder bridge, but the causes of it is difficult to reach consensus. A three-spans continuous pre-stressed concrete box girder bridge is studied in this paper. The web inclined cracks near L/4 of the continuous girder bridge is simulated by FEM (finite element method), in order to explore the influences of web inclined cracks near L/4 on the overall deflection of the bridge and the effect differences of the crack width, length and numbers. The results show that when the web inclined cracks reach a certain level, it will cause a long-term sustainable development of the deflection of the bridge. Therefore, web inclined crack is the main factor that causes the sustainable development of long-term deflection of large span pre-stressed concrete continuous box girder bridges.

Launching of the Reno Bridge on the A1 Highway, Italy

The new Reno Bridge, located at the foot of the Appennine chain near Bologna, belongs to the wide plan of modernisation provided for the improvement of the A1 Milan–Naples highway, called Variante di Valico.The bridge is a curved continuous prestressed concrete box girder 572,75 m long, supported by reinforced concrete vertical piers for the first six spans of 45 m and by two special framed Vshaped piers, which are rigidly connected to the deck, for the remaining “long span” zone (90 + 135 + 90 m). One of the peculiar aspects of the design is the construction process. Because of a very stringent working schedule, it was decided to plan for an incrementally launched structure, realised through the longitudinal launch of 45 m long segments. The special piers of the long span zone are formed by a concrete core encased in steel shells having the double function of formwork during casting, and reinforcement along the service life of the element. The inclined elements of the special piers, which are provisionally supported by auxiliary piers during launching, are rigidly connected to the deck once the structure has reached its final position. Figure 1 shows the new structure just before the opening of the south carriageway; on the left side the old alignment, no longer used, can be seen.

Launching of the Reno Bridge on the A1 Highway, Italy

The new Reno Bridge, located at the foot of the Appennine chain near Bologna, belongs to the wide plan of modernisation provided for the improvement of the A1 Milan-Naples highway, called Variante di Valico. The bridge is a curved continuous prestressed concrete box girder 572.75 m long, supported by reinforced concrete vertical piers for the first six spans of 45 m and by two special framed Vshaped piers, which are rigidly connected to the deck, for the remaining "long span" zone (90 + 135 + 90 m). One of the peculiar aspects of the design is the construction process. Because of a very stringent working schedule, it was decided to plan for an incrementally launched structure, realised through the longitudinal launch of 45 m long segments. The special piers of the long span zone are formed by a concrete core encased in steel shells having the double function of formwork during casting, and reinforcement along the service life of the element. The inclined elements of the special piers, which are provisionally supported by auxiliary piers during launching, are rigidly connected to the deck once the structure has reached its final position

Bridge Strengthening with Additional Prestressing

This paper discusses the application of additional prestressing tendons for rehabilitating and strengthening bridges, which has been widely used during recent years. Additional encased tendons in a widened cross section use proven prestressing systems. Various types of external tendons have been investigated; they have different cross section, sheathing, deviation points, anchoring methods, corrosion protection, and application to existing structures. Thorough analysis, design and construction are required to anchor additional prestressing tendons, where forces of up to 5MN and more are transmitted to the existing concrete structure. In general, the use of prestressing tendons, either encased in concrete or installed externally, is an effective technique to: (1) strengthen bridges; (2) prevent further cracking; (3) re-establish the compression forces of an uncracked condition; and (4) control stresses and deflections. Two case studies are given of the technique's application: (1) strengthening, with encased tendons, of a four-span continuous prestressed concrete motorway bridge, built in 1963; and (2) strengthening, with external tendons, of a three-span continuous prestressed concrete box girder bridge.

Tauranga Harbour Crossing Stella Passage Bridge

This paper describes the seismic design of the Stella Passage Bridge which was constructed in 1986 to 1988 as part of the Tauranga Harbour Crossing, a road link between Tauranga and Mount Maunganui. The bridge is a 12 span, 478m long incrementally launched continuous prestressed concrete box girder with expansion joints at both abutments. Seismic restraint is provided by means of shear keys to ductile cantilever single stem pier columns supported on large diameter bored pile cylinder foundations.