Building Structures and Structural Design
Design basis
Structural design in Belarus follows the SN and Eurocode-aligned STB framework, using limit-state philosophy: ultimate limit states (strength, stability, fatigue) and serviceability limit states (deflection, crack width, vibration). Candidates must know partial safety factors for permanent and variable loads, load combinations, and the role of the importance (responsibility) class of a building.
Structural systems
Understand the behaviour of reinforced concrete (flexural, shear, punching), steel (buckling, slenderness, connection design), masonry (compressive strength, eccentricity), and timber (moisture, fire charring). Know foundation types: shallow pads, strip footings, piles (driven and bored), and the role of frost depth and soil bearing capacity. Distinguish bearing walls from curtain walls and frame from braced systems.
Common traps
- Applying the wrong load combination factor; variable loads are reduced when combined.
- Confusing the importance class with the safety factor of the material.
- Forgetting that deflection limits are serviceability, not strength, checks.
- Assuming pile capacity equals the material capacity of the pile - it is governed by soil resistance.
Worked example
A simply supported RC beam spans 6 m under a uniform design load of 20 kN/m. Maximum bending moment = wL²/8 = 20 × 36 / 8 = 90 kN·m. Compare this with the design resistance moment of the section; if the section provides 100 kN·m, the ultimate limit state is satisfied but serviceability deflection must still be checked separately.
Rule of thumb
Always check both limit states; a section that passes strength can still fail deflection, and a section that passes deflection can still fail stability.