Hi all,

A couple of questions as follows:

1.Non-linear analysis.

If understand this right, this refers to the incremental loading procedure that occurs for the situation when one considers large overall deformation/second order effects and / or truss members. Could I get some clarification on the following:

a) If no truss members are present in a structure then selection of non-linear static analysis is a way of accounting for the second order effects (I've checked a few simple examples by hand and they seem correct).

b) I have a frame which is part tension braced (cross bracing in elevation), but also acts as a part sway frame at higher levels. Obviously I am getting the default switch to non linear analysis (due to the tension members), but does this also automatically account for the geometric non-linearity due to the sway deflection?

c) I also have convergence problems with my model, but only when the bracing members are modelled as tension only - if truss or compression members then convergence is fine. Is this most likely due to a modelling error. We are modelling the columns as continuous members through floor levels, which I now understand to be incorrect? (structure is a simple 3d frame only with no plates).

2. Calculation of required reinforcement for slabs.

a) I have noticed a discrepancy between the required reinforcement results for a simple plate (reinforced for bending only) when comparing the RSA output to a hand calculation to both BS8110 and EC2 using the W&A moments obtained from the software. Is it possible to provide a worked example of the RSA calculation method to a particular code, or let me know how I can display this in full. Typically I end up with a bigger area of reinforcement when doing the hand calc.

Aside from that, good software, thanks for your help!