by curious_iza
 P: 6 Hi I have tried this question and am struggling to work it out; A concrete concrete tunnel with 2m x 2m dimensions on the outside (in cross section) with a uniform wall thickness of 200mm, is used to support a live load of 4kN/m^2 on its top surface. The density of the concrete is 25kN/m^3. The structure has 4 supports. a) Calculate the dead load (G) and live load (Q) along its length in kN/m. b) Calculate the ultimate state design load in kN/m of the concrete tunnel by applying the appropriate load factors of 1.2 and 1.5. Obviously I have do work... 1) I got the cross section of the area which worked out to be 4m^2... 2) I then worked out the 'hollow' part since the thickness is only 200mm I got the 'empty' area as (2 - 0.2 -0.2)^2 = 2.56. 3) I subtracted this to get the actual cross section of the concrete. 4) I then made the length of the beam = Lm. And using the cross section and the Lm length I multiplied the cross section by the length to get the volume. Since density was given I multiplied volume by density and got 36L kN/m. 5) I then divided by L to get the force per m... I dunno if I did all above right ... if so how do I tackle this question!!! Thankyou for your time. Kind regards, Isabelle Attached Thumbnails
 P: 619 What is there in your problem to give you a live load at all? Do you have some design spec that calls out a live load for you? Nothing you mentioned in the problem statement sounds like a live load at all. Something seems to be missing here.
 P: 6 Hi, they give the live load of the top layer (which is 4kN/m^2) ... I have attached the file with the exact question asked (If you would like a diagram). Thanks.
P: 619