Analytical Study on Curved Box Girder Bridges with Minimum Horizontal Stiffeners

Author(s):  
Junichi Adachi ◽  
Takashi Yamaguchi ◽  
Kohei Funayama ◽  
Shintaro Arai ◽  
Michiaki Takao

<p>Curved box girder bridges are widely used in viaducts in urban areas, as well as highway junctions. In fabricating curved box girders, automatic welding robots cannot be applied to welding of horizontal stiffeners to the web panel due to the girder curvature and manufacturing costs increase. <span>Elimination or reduction of the number of horizontal stiffeners is desirable. In this study, </span>FE analysis was carried out varying the curvature and the width-thickness ratio of the structural components as structural parameters to propose the curved box girder bridges without horizontal stiffeners in the web panel. In order to evaluate <span>the ultimate strength, the collapse mode (buckling of lower flange, web panel or stiffeners) has been clarified considering the </span>design sectional forces such as torsional moment, bending moment and shearing force.</p><p>From the results, it was found that the curvature has little influence on the bending buckling strength of the web panels. Even if the horizontal stiffeners are eliminated, the ultimate strength doesn’t decrease until compressive flange buckling occurs. It is concluded that the ultimate strength is governed by the buckling of the compressive flange, even when the bending buckling occurs in the web panel.</p>

2021 ◽  
Author(s):  
Manal Ibrahim

Bridges formed of concrete deck slab over built-up steel-box girders are frequently used in bridge construction for their economic and structural advantages. Box girder bridges impose structural challenges to get the straining actions for the design of girders. The objective of this study is to determine the load distribution characteristics for continuous composite multiple–box girder bridges under CHBDC truck loading. An extensive parametric study was conducted using the three-dimensional finite element to evaluate the moment and shear distribution factors when bridges subjected to CHBDC truck loading. The parameters considered in this study are the span length, number of lanes and number of boxes. Then, simple empirical formula for the bending moment and shear force were developed for the structural design. Correlation of the developed expressions based on FEA results with available CHBDC and AASHTO-LRFD formula showed that the former allow engineers to design such bridges more economically and reliably.


2021 ◽  
Author(s):  
Manal Ibrahim

Bridges formed of concrete deck slab over built-up steel-box girders are frequently used in bridge construction for their economic and structural advantages. Box girder bridges impose structural challenges to get the straining actions for the design of girders. The objective of this study is to determine the load distribution characteristics for continuous composite multiple–box girder bridges under CHBDC truck loading. An extensive parametric study was conducted using the three-dimensional finite element to evaluate the moment and shear distribution factors when bridges subjected to CHBDC truck loading. The parameters considered in this study are the span length, number of lanes and number of boxes. Then, simple empirical formula for the bending moment and shear force were developed for the structural design. Correlation of the developed expressions based on FEA results with available CHBDC and AASHTO-LRFD formula showed that the former allow engineers to design such bridges more economically and reliably.


2021 ◽  
Author(s):  
Ulrik Sloth Andersen

<p>This paper presents the basic principles for strengthening of bridges and other structures through the use of external prestressing. A case study that includes strengthening of the approach spans for the Langeland Bridge in the south-eastern part of Denmark is included.</p><p>During a recent rehabilitation, corrosion of the post-tensioned tendons was discovered inside the box girders of the bridge. Additional analysis of the extent of the corrosion and a structural assessment was undertaken. Based on this, a strengthening project was carried out, and strengthening with external prestressing is currently being implemented.</p>


Author(s):  
Adam McManus ◽  
Daniel Tofful ◽  
Rafal Wozniak

<p>A study of recent work undertaken on the Caulfield to Dandenong Level Crossing Removal Project and West Gate Tunnel Project in Melbourne Australia. The viaducts on these projects were precast segmental box girders erected span-by-span with match cast dry joints which present several key advantages in brownfield construction of linear infrastructure.</p><p>These case studies consider the application of Australian and International design standards to the design of Australian Infrastructure. It is acknowledged that international design standards such as AASHTO have moved away from the use of match cast dry joints however in the Australian context they are still relevant, and it has been necessary to interrogate current standards to establish a suitable design basis. This approach is imperative when assessing existing infrastructure like recent work on the West Gate Tunnel Project which involved the assessment of the existing precast segmental City Link Viaducts. This study seeks to present recommendations on how AS5100.5 may be modified to provide a more practical and efficient solution for the design of new and the assessment of existing infrastructure.</p>


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Hanzheng Xu ◽  
Xiaofeng Yan

Concrete box-girder bridges are widely used in China. During several routine inspections of two-year-old highway bridges of this type in the China Central Plains region, we found that transverse cracks are widespread on the bottom flanges of those box girders, mainly distributed in the area of 1/4L to 3/4L of the span. Selected cracks were then monitored continuously for one year. Our results showed that there had been no change in the widths of the cracks, but their lengths had increased and new cracks had formed. Taking into consideration factors like hydration reaction, relative humidity difference, shrinkage and creep, sunlight thermal differential effect, sudden temperature change, vehicle load, and their combined efforts, we have developed spatial structural models and conducted stress analyses on the reinforced concrete and prestressed concrete box-girder bridges, respectively. Our numerical analysis results indicated that the hydration reaction is the main reason for the initial bottom flange crack and the temperature difference between the inside and the outside of the box girders caused the crack developments at the later stage.


1995 ◽  
Vol 22 (1) ◽  
pp. 93-105 ◽  
Author(s):  
M. S. Cheung ◽  
S. H. C. Foo

Because of their excellent torsional capacity, box girders are used extensively in modern bridge construction having curved alignments. Applications of most design codes have been limited to bridges where the radius of curvature is much greater than the span length and cross-sectional dimensions. To meet the practical requirements arising during the design process, simple design methods are needed for curved bridges. This paper presents the results of a parametric study on the relative behaviour of curved and straight box-girder bridges and on the development of a simplified design method for the combined longitudinal moment of curved bridges. The combined moment includes the effects of flexure, torsion, and distortion. Three simply supported concrete-steel composite bridge models, including single-cell, twin-cell, and three-cell box girders and subjected to loadings as specified in the Ontario Highway Bridge Design Code, were analyzed using the finite strip method. The parameters considered in the study include types of cross section; types, locations, and magnitudes of loads; span lengths; and radius of curvature. Preliminary analysis of the results suggests that the behaviour of horizontally curved box-girder bridges is dependent on a variety of parameters, but most importantly on the span-to-radius ratio. Empirical relationships for combined longitudinal moment between curved and straight box-girder bridges are also proposed. Key words: bridge, curved, composite, design, finite strip.


1984 ◽  
Vol 11 (4) ◽  
pp. 771-781 ◽  
Author(s):  
O. E. Ramakko

The two bridges featured are precast segmental concrete box girders built by the balanced cantilever method. Crossing a hydro tailrace, this $11 million project forms a part of the new Highway 406 through St. Catharines, Ontario. Several unique features of the structures are highlighted. These features include transverse rib beams employed at each segment face to support the deck slab; flaring of the deck slabs to accommodate on and off ramps; and twisting horizontal alignment of the highway. Both bridges have a depth-to-span ratio of 1:27, which results in one of the most slender precast box girder bridges built by the balanced cantilever method. The construction phase of this project is reviewed with particular attention to the casting operation and to the erection of the segments employing a steel launching truss. Design- and construction-related problems encountered are presented and reveal that the more perplexing problems are generally those not related to the complexities of the segmental form of construction but rather to the more mundane aspects of posttensioned concrete bridge construction. Key words: precast segmental concrete box girder bridges, balanced cantilever methods, steel launching truss, short line casting bed.


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