Predictions of crack width for prestressed concrete deck slabs in box girder bridges

2010 ◽  
Vol 163-167 ◽  
pp. 3551-3554
Author(s):  
Wei Peng ◽  
Zhi Xiang Zha

This template Based on cracks observation and finite element analysis of real engineering projects as well as bridge load test after reinforcement, causes and types of cracks in prestressed concrete box girder bridges and treating measurements are systematically studied. The results obtained from the calculation are presented to demonstrate the effect of sensitive factors, such as arrangement of longitudinal prestressed tendons, the magnitude of vertical prestressed force, temperature gradient, etc. The results show that the arrangement of longitudinal prestressed tendons and the magnitude of vertical prestressed force take key roles in cracks control of box girder webs. Lots of treating measurements are presented in accordance with different types of cracks, some of them are applied to a reinforcement engineering of a long span pretressed concrete continuous box girder bridge with cracks. Load test after reinforcement of the bridge demonstrates the reasonability of the treating measurements. Several design recommendations and construction measures about reinforcements and some sensitive factors mentioned above are proposed to control cracks.


2012 ◽  
Vol 204-208 ◽  
pp. 2209-2213 ◽  
Author(s):  
Ya Jiang Du ◽  
Bing Wen Yang ◽  
Shui Wan

In the construction of prestressed concrete(PC) box-girder bridge with corrugated steel webs used cast-in-place cantilever method, the key component-corrugated steel webs are fabricated in factory first and then transported to the construction site. Because of the low out-of plane stiffness, corrugated steel webs are easy to deform in the construction, which brings many difficulties for construction. The precision of installing the corrugated steel web has a direct effect on the cross-section shape of the box-girder. So it is a key step to monitor the orientation and installation of corrugated steel web during construction. Based on the experience of some PC box-girder bridges with corrugated steel webs having been built, a method to control the installation accuracy of corrugated steel webs is proposed and some quality assurance measures are introduced in order to ensure the accuracy, reliability and security of the installation of corrugated steel web. The method can be taken as a reference in the construction of this kind of bridge.


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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