Department of CE, U18CE506 Design of Steel Structures
KITSW 5CE2 AY:2022-
23
CDT4 - LECTURE SUMMARY
CDT4 1.Loads and load combinations, Partial safety factors
Topics Covered
In general, limit state design makes use of the concept of
Motivation
design strengths and design loads, obtained by applying partial
(Why you safety factors and other factors such as the combination factors
(students) should to characteristic or representative values of strengths or loads.
learn these In exceptional cases, it may be appropriate to determine design
topics?)
values directly. However, the values should be chosen to
correspond to at least the same degree of reliability implied in
the codes.
Lecture Learning Outcomes (LLOs):After completion of this lecture, you
should be able to…
LLO1
On topic
Categorize Various loads and load combinations.
1
CDT4 – Lecture Summary – Key Takeaways
Partial safety factors are used to take account of:
• possible unfavorable deviations of the characteristic values
• possible inaccurate modelling of the characteristic values
• uncertainties in the assessment of the effects of actions, geometric
properties and resistance model
Combination factors are used when actions are combined to take account of the
reduced probability of simultaneous occurrence of the most unfavorable values of
several independent actions. Combination values may be used for the verification of
ultimate limit states and irreversible limit states.
CDT4 – Lecture Summary
Actions (Loads)Cl. 5.3
i) Direct actions experienced by the structure due toself-weight and external actions
ii)Imposed deformations such as due to temperatureand settlement
Classification of actions Cl. 5.3.1
• Permanent action
• Variable action
• Accidental action
Limit state method will be used-
The objective of the design is to achieve a structure that will remain fit for use
during its life with acceptable target reliability. In other words, the probability of a
limit state being reached during its lifetime should be very low.
In the limit state method reliability based analysis is performed and based on a
particular dependability safety factors are calculated.
Two types of safety factors are used
• Partial Safety factor-Loads
• Partial Safety factor-materials
Characteristic Actions (Q c) Cl. 5.3.2
Design Actions (Q d) - Cl. 5.3.3
Dr. S. Sunil Pratap Reddy Page 1 of 3
KITSW 5CE2 AY:2022-
23
CDT4 - LECTURE SUMMARY
CDT4 1.Loads and load combinations, Partial safety factors
Topics Covered
In general, limit state design makes use of the concept of
Motivation
design strengths and design loads, obtained by applying partial
(Why you safety factors and other factors such as the combination factors
(students) should to characteristic or representative values of strengths or loads.
learn these In exceptional cases, it may be appropriate to determine design
topics?)
values directly. However, the values should be chosen to
correspond to at least the same degree of reliability implied in
the codes.
Lecture Learning Outcomes (LLOs):After completion of this lecture, you
should be able to…
LLO1
On topic
Categorize Various loads and load combinations.
1
CDT4 – Lecture Summary – Key Takeaways
Partial safety factors are used to take account of:
• possible unfavorable deviations of the characteristic values
• possible inaccurate modelling of the characteristic values
• uncertainties in the assessment of the effects of actions, geometric
properties and resistance model
Combination factors are used when actions are combined to take account of the
reduced probability of simultaneous occurrence of the most unfavorable values of
several independent actions. Combination values may be used for the verification of
ultimate limit states and irreversible limit states.
CDT4 – Lecture Summary
Actions (Loads)Cl. 5.3
i) Direct actions experienced by the structure due toself-weight and external actions
ii)Imposed deformations such as due to temperatureand settlement
Classification of actions Cl. 5.3.1
• Permanent action
• Variable action
• Accidental action
Limit state method will be used-
The objective of the design is to achieve a structure that will remain fit for use
during its life with acceptable target reliability. In other words, the probability of a
limit state being reached during its lifetime should be very low.
In the limit state method reliability based analysis is performed and based on a
particular dependability safety factors are calculated.
Two types of safety factors are used
• Partial Safety factor-Loads
• Partial Safety factor-materials
Characteristic Actions (Q c) Cl. 5.3.2
Design Actions (Q d) - Cl. 5.3.3
Dr. S. Sunil Pratap Reddy Page 1 of 3
