The new method of improving stiffness by casting concrete at the negative moment area

 

 There are so different between maximum magitude of positive moment and negative momente. If we design the bridge of uniform section with negative momente, pasitive momente area is designed very large and It's not economical. otherwise we use the ununiform section, it is not only difficult to design, contruction but extravagant.

 In this method, To improve these weak point, we increase the stiffness by casting concrete that advantageous on compress in the below of both side of section at the negative momente area and we can design the whole section in uniform section with maximum positive momente. In these reason, We can reduce the 20% of hight compare to existing steel box section. This method is more useful than existing continuous steel box bridge in space of brlow structure, and reduce the material of used and advantageous in vibration, absorbing lauance and protecting corrosion by casting concrete.

 In the existing constrction method, It vary the thick of flange for the magitude of momete variation. But we use the uniform section at the joint of positive and negative momentive. We can reduce the welding and advantageous in the lateral shear flow.

 

Three-span continuous beam under uniform distributed load.

 

 

Existing uniform section of three-span continuous steel-box girder.

 

 

 

Existing ununiform section of three-span continuous steel-box girder.

 

 

The new method of uniform section of three-span continuous steel-box girder.