Experimental-Numerical Study on the Flexural Ultimate Capacity of Prestressed Concrete Box Girders Subjected to Collision

Abstract

Precise evaluation for flexural ultimate capacity of bridges which are subjected to the collision of over-height trucks is essential for making decisions on corresponding maintenance, strengthening or replacement. When the span of a cross-line continuous bridge with a double-box girder was hit by an overly high vehicle, the concrete floor of one girder was severely damaged, and part of the prestressed strands and reinforcements in the girder were broken. After the double-box girder was removed and separated into two single box girders, the ultimate flexural capacity of both box girders was studied by destructive tests, and a comparison was made between the damaged and undamaged girders. Moreover, finite element analysis was conducted to simulate the failure process. The results show that the flexural bearing capacity of the damaged box girder decreased by 33%, but it was still 1.07 times greater than the design bearing capacity, which basically meets the design requirements. Also, the damaged box girder showed a desirable serviceable limit state for three-axle vehicles and five-axle vehicles, but showed an undesirable serviceable limit state for six-axle vehicles. This study shows that repairing or strengthening the damaged span may be better than demolishing and rebuilding the whole superstructure bridge.

Experimental and Numerical Study of the Ultimate Flexural Capacity of a Full-Size Damaged Prestressed Concrete Box Girder Strengthened with Bonded Steel Plates

“…The basic information of the bridge is detailed in a reference [ 24 ], and Figure 1 shows the whole layout of the bridge in detail. The expressway is crossed by the third and fourth spans of the bridge, and the traffic flow under the bridge is large.…”

“…Due to a collision by an overhigh vehicle, a girder was severely damaged in the third span and another in the fourth span, as shown in Figure 2 . The damaged #4-2 girder and the undamaged #4-1 girder of the fourth span were compared and studied [ 24 ]. In this paper, the bearing capacity of the damaged #3-2 girder of the third span, which was repaired and strengthened with steel plates, was studied.…”

“…The modeling process of the undamaged #3-2 girder complied with the modeling process of the undamaged #4-1 girder. The modeling details of the undamaged #4-1 girder were described in Section 3.3 of another paper [ 24 ], and Figure 9 shows the stress-strain curves of the concrete, pretensioned strands and steel bars. Linear truss elements and eight-node hexahedral reduction integral elements were applied to establish the steel bars, pretensioned strands model and the concrete model, respectively.…”

“…We take a prestressed concrete box girder bridge as the research object, specifically the third and fourth spans of the cross-line that were severely damaged when struck by a truck. The mechanical properties of the damaged and undamaged fourth span box girders were compared previously [ 24 ]. The technical status of the bridge was assessed, and the bearing capacity of the third span in the damaged girder was checked according to the specification [ 6 ].…”

Analysis of The Working Performance of Large Curvature Prestressed Concrete Box Girder Bridges

“…Static or dynamic experiments of curved girder bridges have been used to investigate their structural working behavior relative to curvature. For example, YongLi et al [ 24 ] performed dynamic ultimate flexural load capacity tests on prestressed concrete box girders and analyzed scenarios such as the ultimate bending capacity of undamaged and damaged box girders. Kim et al [ 25 ] constructed a 40 m long double girder curved precast prestressed concrete bridge using a multitasking formwork and performed static flexural tests to evaluate its safety and serviceability performance.…”