What is Negative Skin Friction, Calculation of Negative Skin Friction?

Negative skin friction occurs when concrete piles are situated in soft soils, consolidating soil-mass, etc., resulting in a downward force that increases loading on shaft piles and reduces the bearing capacity of the piles. A new concept based on the shifting rate of piles, and the settlement rate of the surrounding soils has been suggested … Read more

What is Tunnel Boring Machine (TBM), Advantages and Features

TMB is used as an alternative to drilling and blasting (DB) methods. TBMs are used to excavate tunnels with a circular cross section through a variety of subterranean matter; hard rock, sand or almost anything in between. As the TBM moves forward, the round cutter heads cut into the tunnel face and splits off large … Read more

how should the guided bearings in piers of the curved region be oriented with respect to the fixed bearing in abutment?

To determine the orientation of guided bearings, one should understand the movement of curved region of a prestressed bridge. Movement of prestress and creep are tangential to the curvature of the bridge (or along longitudinal axis) while the movement due to temperature and shrinkage effects are in a direction towards the fixed pier. If the … Read more

What are the advantages of piers constructed monolithically with the bridge deck over usage of bearings?

Basically, piers constructed monolithically with the bridge deck are advantageous in the following ways:(i) Movement of the bridge deck is achieved by the bending deformation of long and slender piers. In this way, it saves the construction cost of bearings by using monolithic construction between bridge deck and piers. Moreover, it is not necessary to … Read more

Are diaphragms necessary in the design of concrete box girder bridges?

Diaphragms are adopted in concrete box girder bridges to transfer loads from bridge decks to bearings. Since the depth of diaphragms normally exceeds the width by two times, they are usually designed as deep beams. However, diaphragms may not be necessary in case bridge bearings are placed directly under the webs because loads in bridge … Read more