Beam on elastic foundation is the best way for foundation design!

you model the soil using Area spring/spring properties and the software will capture the interaction between the foundation element and the soil. This approach will give you a better understanding and design moment or shear specially for mat foundations.

I have some tips:
Tip 1: In the absence of plate load test result you can use an approximate method to determine the soil su bgrade reaction. Bowels has proposed the following equation, Ks=40*SF*σall (SF-safety factor, σall allowable bearing capacity).

Tip 2: don’t reinforce your mat or footings with the maximum moment around columns. Since the design moment is located at the face of column, at least try to read the moment at the face of column. Otherwise you would reinforce your mat for peak moment and end up being uneconomical.

Tip 3: don’t forget to model the lateral passive earth pressure preventing your footing from sliding. Otherwise your model would be unstable.

Tip 4: If you are using SAFE, you can model the soil with “soil property” and you can draw strips to help you read moment easily and perform a better design (since strips include torsional moment in calculating design moment, it makes your work easy. If you use finite element method to design your footing elements, don’t forget to use WOOD and ARMER method to allow torsional moments in your design.

Monolithically caste RCC beam and slab have the tendency to create T/L beam effect even if the beams are intended to be rectangular once. The portion of the slab close to the beam would try to share part of the compressive longitudinal stress developed along the beam.

T/L beam is simply the result of the location of the beam. Internal beams develop T beam effect while edge beams develop inverted L beam effect. Both beam types follow almost similar design principle, they only differ in the portion of slab to be considered as part of the slab.

T/L beam effect, for drop beams (beam whose top is in similar elevation with the slab top), is observed for hogging or positive moment regions. Since concrete is effective in carrying only compression, it is convenient to state for a uniformly loaded simply supported beam that mid-span regions can be designed by taking into consideration the T/L beam effect. On the other hand, sagging or negative moment regions would lead to the development of tensile stress in the flange, which would automatically render the concrete useless since concrete can’t carry tension.

while designing T/L beams the location of the neutral axis plays a vital role. Since the neutral axis can be in the flange or in the web, we must first exactly locate where it is. Once the location of the neutral axis is determined either of the two cases would be followed to design the beam, 1) neutral axis within the flange(xu<Df) in this case the beam would act as a rectangular beam with width equal to the width of the flange. This is due to tension being below the neutral axis. 2) neutral axis within the web(xu>Df). This leads to a more demanding analysis to determine the effect of the flange and web in compression.

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