1. Limit state design method2
Limit state design method

2. Limit state design method
If you have any doubts, you can check your textbook, pp

3. Limit state design method
Lesson 2
Calculation procedures Having defined
G = geometric characteristics of the structure
Q = external stresses
f = resistance of the materials
– Checking procedure: it is carried out when all the sizes of the structure and the external stresses are known and we want to compare the resistance of structure R with the external stresses E R (f, G) ≥ E (Q)
– Design procedure: it is carried out when we want to determine the geometric characteristics of the structure already knowing the external stresses and the characteristics of the materials. Geff ≥ G (Q,f)
– Testing procedure: it is carried out when the geometric characteristics, the external stresses and the resistance of the materials are known and we want to compare the maximum load that the structure can bear with the load to which it is subjected.
Qmax (f,G) ≥ Q

4. Limit state design method
Lesson 3
• Ultimate limit state (ULS): a serious condition of instability that can create environmental and social damage; compromise people’s safety; put the building out of working use.
• Serviceability limit state (SLS): less serious damage that can compromise the functionality of the building during use.
Overpassing ULS
Overpassing SLS
Irreversible
Reversible
Structural failure
Damage

5. Limit state design method
Lesson 4
• Scenario E (External) Assessing the parameter that induces the limit state (for example, breaking strength or deformation) depending on the stresses external to the structure under examination (weights, variable loads, heat variations etc.). For example if the chosen parameter is a Moment, the scenario E is the Moment created by the forces that will presumably be applied to the structure.
• Scenario R (Resistance) Assessing the same parameter through the analysis of the resistance of a structure, determined essentially by the material and by its size and geometric form. Following the previous example, the scenario R is therefore the Moment which, once applied to the structure, causes the desired limit value to be reached.
The result must be R > E
Partial coefficients:
γQ for variable loads (to be multiplied by)
γG for permanent loads (to be multiplied by)
γP for pretension loads (to be multiplied by)
γM for the characteristics of the materials (to be divided by)
γE for the calculus model (to be divided by)

6. Limit state design method
Lesson 5
NOMINAL LIFE ACCORDING TO THE DESIGN
FOR TYPE OF BUILDING
Type of building
Nominal life VN
years
Classes of buildings and coefficients of use
Class

7. Limit state design method
Lesson 8
Elastic section modulus
Plastic section modulus Wpx = 2 · Sx
Stresses – elastic phase
Stresses – complete plasticization

8. Limit state design method
Lesson 11
Load combinations
COMBINATION
LOAD COMBINATION EQUATION Fd
USE
USL fundamental
SLS characteristic rare
frequent
quasi-permanent
Seismic USL and SLS
Ultimate limit states
SLS irreversible
SLS reversible
SL for long-term effects
Seismic actions E
Where:
Partial coefficients
Combination coefficients
Actions due to permanent loads
Actions due to variable loads

9. Limit state design method
Lesson 11
Partial coefficients
Combination coefficients
USL and SLS
UNFAVOURABLE
FAVOURABLE
CATEGORY
Category A – Spaces for residential use
Category B – Offices
Category C – Spaces subject to crowding
Category D – Spaces for commercial use
Category E – Libraries, archives, storehouses and spaces for industrial use
Category F – Garages and car parks (for vehicles weighing ≤ 30 kN)
Category G – Garages and car parks (for vehicles weighing > 30 kN)
Category H – Roofings
Wind
Snow (≤ 1000 m height above m.s.l.)
Snow (> 1000 m height above m.s.l.)
Heat variations