DESIGN PHILOSOPHY Flashcards
It is a limit state condition due to probable collapse of a structure or part of it.
Strength Limit State
It is a limit state condition due to disruption on the functional use of a structure.
Serviceability Limit State
A design procedure where in the structure or its members are arrange and proportioned so that no applicable limit state condition is exceeded when subject to all appropriate load combination
Limit State Design
ASD stands for
Allowable Stress Design
LRFD stands for
Load Resistance Factor Design
TRUE OR FALSE
ASD and LRFD differ primarily on providing adequate factors of safety on serviceability limit state while strength limits are the same
FALSE
Same in serviceability, Different in strength
Safety Criterion for Designing Steel
Resistance > Load
What do you use to avoid experiencing failure?
Factors of Safety
What will happen to the failure and cost if the reliability index (β) is too big?
Failure will be too small but the structure will be costly
In LRFD load combination 3,4,5, L may be reduced to 0.5L if L is
greater than 100psf or 4.8kPa
ASD is limited to _____ behaviour
Elastic
LRFD’s factor of safety is based on ____ and _____
probability and statistical assessment
Overloads may arise due to:
1.
2.
3.
4.
- Uncertainties and variability on distribution of loads
- Change in occupancy
- Underestimation of load effects
- Variation in construction procedures
Phi value for Tension Members
Yielding - 0.90
Fracture - 0.75
Phi value for Compression
0.85
