Department of CE, U18CE506 Design of Steel Structures
KITSW 5CE2 AY:2022-
23
CDT3 - LECTURE SUMMARY
CDT3 1.Ultimate and serviceability limit states,
Topics Covered
Serviceability limit states (SLS) that represent criteria governing
Motivation
normal functional or operational use. Ultimate limit states (ULS)
(Why you that represent the failure of the structure and its components
(students) should usually when subjected to extreme values of actions or action
learn these effects.
topics?)
Lecture Learning Outcomes (LLOs):After completion of this lecture, you
should be able to…
LLO1
On topic
Apply the Design requirements of limit state design.
1
CDT3 – Lecture Summary – Key Takeaways
In limit-state assessment, such various limit states are considered against different
target safety levels; the target to be attained for any particular type of limit state is
a function of the consequences and ease of recovery from that state.
LSD involves estimating the subjected loads on a structure, choosing the sizes of
members to check, and selecting the appropriate design criteria. LSD requires two
principal criteria to be satisfied: the ultimate limit state (ULS) and the serviceability
limit state (SLS).
CDT3 – Lecture Summary
The performance of a structure and its components is described using limit-state
functions that separate desired states from undesired states. The physical effects of
exceedance of a limit state may be either reversible or irreversible. For the
reversible case, removal of the cause of the exceedance allows the structure to
return to a desired state. For the irreversible case, the same is not true and certain
consequences, such as damage, may occur depending on the nature of the limit
state. The consequences may, in turn, be either recoverable or unrecoverable from
the deformed state. For example, if the damage is limited, say, in the form of a
localized permanent set in a case where the same is not desired, the condition may
be repairable, for example, by replacing the affected parts.
Limit state design (LSD) refers to a structural engineering design method.
A degree of loading or other actions imposed on a structure can result in a ‘limit
state’, where the structure’s condition no longer fulfils its design criteria, such as;
fitness for use, structural integrity, durability, and so on. Limit states are conditions
of potential failure.
All actions likely to occur during a structure’s design life are considered during the
LSD method, to ensure that the structure remains fit for use with appropriate levels
of reliability.
LSD involves estimating the subjected loads on a structure, choosing the sizes of
members to check, and selecting the appropriate design criteria. LSD requires two
principal criteria to be satisfied: the ultimate limit state (ULS) and the serviceability
limit state (SLS).
Limit states
Limit state of strength
Limit state of serviceability
Limit state of strength: (Cl. 5.2.2.1)
Dr. S. Sunil Pratap Reddy Page 1 of 3
KITSW 5CE2 AY:2022-
23
CDT3 - LECTURE SUMMARY
CDT3 1.Ultimate and serviceability limit states,
Topics Covered
Serviceability limit states (SLS) that represent criteria governing
Motivation
normal functional or operational use. Ultimate limit states (ULS)
(Why you that represent the failure of the structure and its components
(students) should usually when subjected to extreme values of actions or action
learn these effects.
topics?)
Lecture Learning Outcomes (LLOs):After completion of this lecture, you
should be able to…
LLO1
On topic
Apply the Design requirements of limit state design.
1
CDT3 – Lecture Summary – Key Takeaways
In limit-state assessment, such various limit states are considered against different
target safety levels; the target to be attained for any particular type of limit state is
a function of the consequences and ease of recovery from that state.
LSD involves estimating the subjected loads on a structure, choosing the sizes of
members to check, and selecting the appropriate design criteria. LSD requires two
principal criteria to be satisfied: the ultimate limit state (ULS) and the serviceability
limit state (SLS).
CDT3 – Lecture Summary
The performance of a structure and its components is described using limit-state
functions that separate desired states from undesired states. The physical effects of
exceedance of a limit state may be either reversible or irreversible. For the
reversible case, removal of the cause of the exceedance allows the structure to
return to a desired state. For the irreversible case, the same is not true and certain
consequences, such as damage, may occur depending on the nature of the limit
state. The consequences may, in turn, be either recoverable or unrecoverable from
the deformed state. For example, if the damage is limited, say, in the form of a
localized permanent set in a case where the same is not desired, the condition may
be repairable, for example, by replacing the affected parts.
Limit state design (LSD) refers to a structural engineering design method.
A degree of loading or other actions imposed on a structure can result in a ‘limit
state’, where the structure’s condition no longer fulfils its design criteria, such as;
fitness for use, structural integrity, durability, and so on. Limit states are conditions
of potential failure.
All actions likely to occur during a structure’s design life are considered during the
LSD method, to ensure that the structure remains fit for use with appropriate levels
of reliability.
LSD involves estimating the subjected loads on a structure, choosing the sizes of
members to check, and selecting the appropriate design criteria. LSD requires two
principal criteria to be satisfied: the ultimate limit state (ULS) and the serviceability
limit state (SLS).
Limit states
Limit state of strength
Limit state of serviceability
Limit state of strength: (Cl. 5.2.2.1)
Dr. S. Sunil Pratap Reddy Page 1 of 3
