Lu Pan River Bridge

Project overview

Lu Pan River Bridge is located in Baoying County in the south, pile No. K890+226, routes across the X304. Lu Pan River Bridge 532.89m long span group (6 * 25) as m+3 * (5 * 25) m composite box beam. The lower structure is a pile column pier. The bridge design load for steam super 20; -120; bridge deck framing setting arrangement 0.5m (outer fence) +12m (Lane) +1m (inner fence) +1m (median) +1m (inner fence) +12m (Lane) +0.5m (outside the fence); the bridge width of 28.0m.

Periodic inspection

The party in 2009, 2011 and 2013 respectively on Lu Si River Bridge were checked regularly, and at the end of 2014 for the special inspection.

In 2009, there were 18 vertical cracks in the diaphragm. The total length is about 10.8m. There are 48 vertical cracks on the web, which are about 48m long. There are 67 transverse cracks and 24 longitudinal cracks in the wet joints. The transverse cracks are 80.4m long and the longitudinal cracks are 392.5m long.

2011 regular inspection showed that the disease part of the bridge has been in previous years were repaired, regular inspection found the box girder partition has 17 vertical cracks, a total length of 2 15.3m, total length of transverse crack, 1.7m web; there are 4 vertical cracks, a total length of 4m, and has produced 5 webs of albinism; 98 transverse cracks in the wet joint, a total length of 117.6m; beam bottom has 1 longitudinal cracks and 4 transverse cracks.

In 2013, regular inspection, diaphragm there are 73 vertical cracks, 2 transverse fractures, while 8 of white; Web there are 11 vertical cracks, 1 longitudinal cracks, vertical cracks a total length of about 10.5m, longitudinal crack length 12m; wet joint exist 115 cracks, a total length of about 144m, at the same time there analysis of white beam bottom at 31; there are 8 longitudinal cracks and 2 transverse cracks.

In 2014 special inspection, the whole bridge part of the beam has been repaired, but there are still a large number of vertical cracks in the web and the transverse cracks in the floor. There are 228 vertical cracks in the web, and thirteenth holes in the left side. There are 1 straight skew cracks in the web of 2# composite box girder. The width is 0.10mm, and the length is 1.3m. There are 364 transverse cracks at the bottom of the full bridge composite box girder. The total length is 344. 1m. There are 11 longitudinal cracks at the bottom of the whole bridge composite box girder, with a total length of 43.5m.

Disease detection

1.Vertical fracture of Web

Full bridge box girder web plate consists of 228 vertical cracks, of which 227 slit width <0.15mm, length 206.6m, width of 1 0.15mm long, 1m. The cracks are mainly distributed between 1 / 3 span to 2/3 span.

2.Oblique fracture of abdominal plate

There are 1 positive eight character oblique cracks in the webs of the left thirteenth hole 2# composite box girder, with a wide 0.10mm and a long 1.3m, and the cracks are located in the 1/4 span.

3.Transverse cracks in the floor

There are 364 transverse cracks in the bottom of the whole bridge composite box girder, with a width of <0.15mm and a total length of 344.1m, and the cracks are mainly distributed in the middle span of the bridge.

4.Longitudinal cracks in the floor

There are 11 longitudinal cracks in the bottom of the whole bridge composite box girder, with a width of <0.15mm and a total length of 43.5m.

5.Concrete defects

The bridge has a total of 2 concrete hollow, total volume of 1 0.00017m fand; concrete spalling, an area of 3.5 square meters; there are 1 pits, an area of 0.45 square meters; 1 expansion reinforcement, length of 0.5m.

6.Bearing disease

A total of 110 full bridge bearing bearing circumferential crack 0.5mm, 53 bearing circumferential crack 1mm, 7 bearing circumferential crack 1.5mm, 7 bearing circumferential crack 2mm, 4 bearing circumferential cracking 3mm 4 supports local void, 4 bearing shear deformation, 17 temporary supporting seat at the end of demolition 8, a supporting seat at the end of the dust cover down.

Rubber bearing cracking may be in the vertical force, between the thin steel plate rubber bearing in rubber will produce compression deformation, and experience to the lateral expansion of convex rubber, rubber deformation and stress of the aging of the corresponding tensile, and cracks appear on the outer surface of the rubber bearing.

Reinforcement measures

In view of the various kinds of cracks and diseases checked out, the following reinforcement measures are taken

--grouting and sealing

Where the crack width is larger than 0.15mm, where do grouting treatment; crack width of <0.15mm, do the sealing treatment.

--external prestressed steel beam reinforcement

Under the actual operating load, the flexural capacity of the secondary span, middle span and span is insufficient, and the fourth joint of the left amplitude is reinforced by external prestressed steel beam.

--bonded prestressed CFRP laminate reinforcement

In the actual operation of loading time, side span and cross bending bearing capacity, the right fourth were strengthened with prestressed CFRP plates, side span box girder each increase of 2 125px wide prestressed carbon fiber plate 3mm, in the span box girder each increase of 3 125px wide. The thickness of 3mm prestressed CFRP plate.