TU Mate Swe

Selecting Footing Size and Reinforcement. Most foundation failures are related to excessive movement rather than loss of load-carrying capacity. In recognition of this fact, settlement control should be the first issue addressed. Once service loads have been calculated, foundation plan dimensions should be selected to limit bearing pressures to those that are expected to provide adequate settlement performance. Maintaining a reasonably consistent level of service load-bearing pressures for all of the individual footings is encouraged since it will tend to reduce differential settlements, which are usually of more concern than are total settlements. Once a preliminary footing size that satisfies serviceability criteria has been selected, bearing capacity can be checked. It would be rare for bearing capacity to govern the size of footings subjected to sustained loads. However, where large transient

 Development length and Lap length addresses the length of the bar needed to transfer the stresses to the other bar whereas Development length addresses the length of the bar needed to transfer the stresses to the concrete. Development length Usually at the end of the section where you have forces in the bar, you need to make sure that bar pullout failure doesn’t happen. In order to resist forces in rebar it has to be embedded in concrete. A development length is the amount of rebar length that is needed to be embedded or projected into concrete to create a desired bond strength between the two materials and also to develop required stress in steel at that section. In the example below we require development length of 10db at the end of the section so that bond between concrete and steel remain continuous. As there is no space at the end of the section bar is bent. Notice that 90 degree configuration is used here more configurations can also be used. For further detail refer to ACI or

Orginal By Ko Aung Su Myat  

Spillway General Dam outlet works consist generally of spillways and bottom (high-head) outlets. Spillways are basically dam appurtenances ensuring a safe passage of floods from the reservoir into the downstream river reach. The spillway design depends primarily on the design flood, dam type and location, and reservoir size and operation. The design of bottom outlet works depends primarily on the purpose of the reservoir and the sediment inflow and deposition in the reservoir. Spillways may be classified in several ways: according to function as (main) service, emergency and auxiliary spillways; according to mode of control as free (uncontrolled) or gated (controlled) spillways; according to hydraulic criteria, i.e. type, as overfall, side channel, chute, shaft, siphon and tunnel spillways. In the following text this last type classification will be used. Apart from economics, the main factors governing the choice of spillway for a given project are the reliability and acc