When calculating berthing energy of vessels, there is a factor called “eccentricity factor” which accounts for different berthing energy when the vessel contact the fender system at different locations of the vessel.

For instance, for mid-point berthing the eccentricity factor is unity which means there is no loss of berthing energy. For third-point berthing and quarter-point berthing, the eccentricity factor is 0.7 and 0.5 respectively. In fact, engineers always attempt to reduce the amount of berthing energy to be absorbed by fender system and pier structures. As such, it is recommended for vessels to contact fender system at its bow or stern because the reaction force would produce a rotational moment to the vessel which dissipates part of vessel’s energy.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

The design of a fender system is based on the principle of conservation of energy. The amount of energy brought about by berthing vessels into the system must be determined, and then the fender system is devised to absorb the energy within the force and stress limitations of the ship’s hull, the fender, and the pier.

Firstly, the energy released by the largest/heaviest vessel allowed to use on the pier is determined to be delivered to the pier by first impact. Then, the energy that can be absorbed by the pier would be calculated. For pier structures that are linearly elastic, the energy is one-half the maximum static load times the amount of deflection. However, in case the structure is extremely rigid, it can be assumed to absorb no energy.

The energy to be absorbed by fender system should be the total energy of berthing vessels deducting the energy absorption by pier structures. Finally, a fender system capable of absorbing the amount of energy without exceeding the maximum allowable force in the pier should be chosen from fender product catalogue.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

In placing concrete by tremie pipes, hoppers are connected to their top for receiving freshly placed concrete. However, air may be trapped inside the tremie pipes if there is rapid feeding of fresh concrete. To release the trapped air inside the tremie pipes, hoses (called ventilation tubes) are inserted and lowered down through the hoppers. Reference is made to Carl A. Thoresen (1988).

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

Let’s consider a pile bent with a top slab supported by two ranking piles, each inclining at an equal angle to the pier slab. In designing such a system, truss action is normally adopted to analyze the pile bent. When the reaction forces of these piles, horizontal forces (e.g. due to berthing and deberthing of vessels) and vertical forces (e.g. superimposed deck loads) are analyzed by drawing a force polygon, it is noted that lateral resistance of the pile bent is dependent on the vertical load, i.e. lateral resistance is small when vertical loads are high.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.

The most severe load on piers generally is the horizontal load due to berthing and mooring of large vessels. The design of piers is taken as an example to illustrate the importance of adequate pile founding level. Since the widths of open berth piers are relatively small so that they provide a short lever arm to counteract the moment induced by berthing loads. Moreover, the dead load of open berth piers are normally quite light and therefore the resisting moment provided by the dead load of pier structures may not be sufficient to counteract the moment generated by berthing loads. To aid in providing adequate resistance to the overturning moment by the berthing load, the soil resistance above bedrock contributes to the stabilizing moment. For commonly adopted marine piling type, i.e. driven steel tubular piles with reinforced concrete infill, driven piles can at most be founded on top of rockhead surface. In case the rockhead level is shallow (e.g. near shoreline), the little soil cover may result in inadequate lateral resistance to the berthing load.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.