Design Philosophies Flashcards
A condition in which structure becomes unsafe due to possible collapse of the structure.
Strength Limit State
Excessive vibration is an example of strength limit state
False
Resistance to flexure is an example of serviceability limit state
False
Working stress design and ultimate strength design are considered limit state design
False
ASD and LRFD are generally the same in terms of providing adequate factor of safety
False
Allowable stress must always be greater than or equal to actual stress is a strength design approach
True
Overloading of structures and under strengthening of members are the factors of safety _______ design method
Load and resistance
The usual factor of safety given to beams and tension members is ______
1.67
Connection design have bigger factor of safety than member design like columns and beams because connection failure are
Brittle
The load factor used in strength design method depends on
type of member
since LRFD or strength design method involved several factors of safety, the probability of failure is given by the margin of safety as well as
Reliability Index
Importance of the member of the structure may affect the reduction factor value
True
LRFD or strength design method will always be safer ans economical than ASD and WSD
True
The potential limit state are the same for every structural member subjected to a specific load requirement
False
Plastic design is and limit state design is a part of a limit state design
True
The allowable strength design method is a patterned after
WSD
The safety criterion in design allows that
R>0
The factor of safety in design is given by
R/Q
In the allowable stress design method, the factor of safety is given to the resistance and no factor of safety is given to the actual ________
nominal strength
when the factor of safety is high, the reliability index is
high
the factor of safety for connection ranges from 2.5 to 3 because it is
critical
LRFD is based on
probability
the coefficient of the load factors for ASD are
based on judgment
factor of safety are provided in LRFD both on factored load and
understrength
reduction of live loads L are made because it is unlikely that the area of load applictation will not cover
less than 50%
LRFD is about
capacity determination
in design survival means
R>Q
In (R/Q)<0= Failure is the same as
both
when a design is conservative it follows that it is
expensive
dead loads differ with live loads depending on how long the load is applied on the member
True
Lr stands for
roof live load
what is the factor of safety for a dead load of 10kn and an understrength factor of 0.85 if the overload factor of 1.2 is applied dead load (Use LRFD)
1.41
determine the value of L if a live load of 100kn is place over a garage area of 20 sqm
5 kpa
why are earthquake and wind not combined for a possible design load combination
they don’t usually exist together
a conservative design is
very safe but expensive
an efficient design is
strong and economical
