Pre-Engineering

In order to make a elastomeric bearing act/ function as a soft spring it should be made to allow it to bulge laterally and also the stiffness compression can be increased by simply increasing the limiting amount of the lateral bulging. In many cases in order to increase the compression stiffness of the bearing the usage of metal plates is made. Once steel plates are included in the bearings the freedom of the bulge is restricted dramatically, also the deflection of the bearing is reduced as compared to a bearing without the presence of steel plates. The tensile stresses of the bearings are induced into the steel plates. But the presence of the metal plates does not affect the shear stiffness of the bearings.

The washout valves are primarily used for normal maintenance works such as that of water main. This can be like to allow water to flow out during the cleaning of the water main. The junctions at which a pipe branches out to a washout point usually a gate valve is installed so that the two pipelines are separated. The gate valve installed above usually remains open during normal operation. Another gate valve is installed further downstream and this remains closed during normal operation of the washout valve. In case this valve is not installed then the pipe section of the branched out pipe would remain dry during normal operation and high chances of damage and leakage can take place. When the downstream valve is installed the branched out water main contains water under normal operation. With two gate valves installed a leakage can be detected immediately.

The major types of reinforcements used in prestressing are:

☛ Spalling Reinforcement: The spalling stresses leads to stress behind the loaded area of the anchor blocks. This results in the breaking off of the surface concrete. The most likely causes of such types of stresses are Poisson`s effects strain interoperability or by the stress trajectory shapes.

☛ Equilibrium reinforcements: This type of reinforcements are required where several anchorages exist where the prestressing loads are applied in a sequential manner.

☛ Bursting Reinforcements: These kinds of stresses occur in cases where the stress trajectories are concave towards the line of action of load. In order to reduce such stresses reinforcements in the form of bursting is required.

Pull out tests are performed for primarily the following reasons:

☛ In order to detect and the verification of the bond strength among the soil and the grout adopted during the design of soil nails. This is considered to be as the primary objective of performing pull out tests for soil nails.

☛ For the detection of any slippage or occurrence of creeps.

☛ To detect the elastic and deformations (plastic) of any of the test nails employed. Observations are made during the loading and unloading cycles of the soil nails repetitively.

☛ To achieve the perfect balance the test nails should always be loaded so that the ultimate soil/grout mixture with an upper limit of 80%.