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@saplanti Thanks for the input. The maximum internal pressure including the effect of surge is about 80 psi and the resulting hoop stress in the penstock steel is 6500psi. You are right that initially i got my terminology wrong since i was wrongly assuming the steel hoop stress as the internal...

Concrete is outside the pipe. And since we are using reinforced concrete so it will take some tension, but yes majority of the tensile stress will go to the penstock steel.

I got it. I was applying hoop stress as the internal pressure, which gave very high pressures.(quit a fundamental mistake i guess). I now applied the internal pressure of 80 psi and the results i am getting are quite reasonable. @Jstephen You are right in that the resulting stress is coming out...

The head is actually only 200' but after adding the effect of transient loading, load rejection and water hammer, the maximum hoop stresses come out equal to 6500 psi. And yes initially we did not take the concrete encasement to be part of the composite assembly, since the penstock was capable...

We are designing the concrete encasement around a steel pen stock for internal loads. Although the pen stock is capable of taking the loads, but we need to find how much load will be transferred to the concrete encasement. Maximum internal water pressure in 6.5 ksi. The steel pipe material is...

Thanks for your comment. The traffic will not be frequent, but some heavy machinery will have to be transported to the powerhouse (the main gate of powerhouse is not far away from this trench) and hence heavy vehicles may pass over it. We are talking about a open area between the switch yard...

Sorry for not making myself very clear in the opening post. Here is the sketch of cable trench i am talking about. I hope this makes it clear. I am confused as to how to design this section of the cable trench which passes over the spillway. I am thinking of designing it as a bridge since...

We have to design a reinforced concrete cable trench for our powerhouse and substation. The area where the cable trench is passing has a spillway (which is covered with a slab). I have been asked to design the section of the trench which will pass over the spillway. Now what would be the best...

Thank you all for you prompt and useful replies. I finally increased the size of the pedestal which satisfied the middle third requirement. Regards,

Well basically i haven't used any load combinations or load factors in my calculations. But I have checked that taking 0.6D gives a factor of safety less than 2 (1.83 to be precise). So i guess i will have to satisfy the check for resultant force.

@cvg Its bearing on rock.

Hi. I am new to this forum and this is my first post/questions. We are basically in the process of designing reinforced concrete pedestal or saddle support for a penstock. I have almost completed the design including the checks for sliding, stability and bearing pressure (with more than...