Overall Design of the Fourth Tuojiang River Bridge in Luzhou

The Fourth Tuojiang River Bridge is a single pylon cable-stayed bridge with a main span of 200 mand the vehicle lanes and the future light transit rails are designed to position on the same deck.The pylon,like agu(a kind of liquor utensil in ancient China),is a steel-concrete composite structure.The girders in the main span and the side spans connecting the new district in west part of the city are left and right separated steel box girders.To reduce the constraint effect inside the structure,diaphragm beams are installed between the two steel boxes at the stay cables,the pylon and the piers,and are connected to the steel boxes with bolts.The main girders in the side spans on the side of new district in the north of the city and both the south and north approaches are prestressed concrete continuous box girders.The concrete box girder and the steel box girder are connected by a 2-m long steel-concrete joint section.To reduce the concrete shrinking stress,a 100-cm wide post-cast concrete section is set on the deck slabs along the bridge central line and over the cross beams.Along the bridge length,the concrete box girder was cast in situ in four segments.Due to that the support reaction force at the approach ends is greater than that at the main bridge girder ends,the central line of the turning pier is made offset away from the pylon,and makes the wall thickness of the piers along the bridge length variable,so as to avoid the occurrence of additional bending moment in the piers because of the existence of the support reaction force difference.