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26 Cards in this Set
- Front
- Back
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What are the purpose of codes? |
To protect the public |
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Who uses codes |
Building jurisdictions Design professionals Other construction professionals |
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What are benefits of codes? |
Protection of public information Sustained knowledge Standardization Accountability |
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Why was the international building code (ibc) created? |
It was developed because of the need for a modern building code that emphasizes performance. |
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What are load combinations factors based on? |
They take all loads, determine when they will be present together, and factor them according to their variability |
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What are the three dominant load groups that load combinations are organized in? |
Gravity, lateral, and overturning |
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What does the gravity load group govern? |
The design of non frame beams and columns |
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What does the lateral load group govern? |
Controls frame members (beams, columns, and frames) |
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What does the overturning load group govern? |
Foundations and anchor design on frame end columns |
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What kind of buildings does the accuracy of wind calculations matter most for? |
Tall slender buildings |
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Why do codes not estimate forces due to tornados? |
The forces are considered to be too violent that it is economically feasible to deign buildings to resist them |
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What is a windward surface? |
A positive pressure on front wall due to wind |
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Leeward surface |
A suction on rear wall due to wind |
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What are the two limits states? |
Serviceabilty and Strength |
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What is a limit state? |
Used to describe a condition at which a structure or part of a structure ceases to perform it's intended function. |
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Load and Resistance Factor Design (LRFD) |
Based on a strength limit state |
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What is a strength limit state? |
Load carrying capacity which includes yielding, fracture, buckling, fatigue |
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LRFD Process |
Estimate service and working loads Decide on largest load combination and then multiply by a load factor (>1) to be used in design and analysis (called factored loads) Check that factored loads are less than the nominal strength Nominal strength is multiplied by resistance factor (<1) |
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What do load factors reflect? |
Uncertainty of the load |
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What is serviceability? |
Defines performance (deflection, cracking, slipping, etc...) |
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ASD Process |
Estimate service or working loads Decided on the largest group and that is what you design for Make sure demand (load group) is less than capacity (nominal strength) Reduce nominal strength significantly by dividing by safety factor (>1) to account for variations in material strength, member dimensions, workmanship |
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What are service or working loads? |
They are expected values of the individual loads (dead, live, wind, snow, etc.) are estimated in exactly the same manner |
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Nominal strength |
Its calculated theoretical strength, with no safety factors or resistance factors |
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How does the calculation of nominal strength differ in LRFD and ASD? |
LRFD: resistance factor usually less than one is multiplied by the nominal strength ASD: the nominal strength is divided by a safety factor, usually greater than 1 |
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Safety Factor |
A number usually greater than 1 used in ASD method and divides the nominal strength |
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Resistance factor |
a number usually less than 1 used in LRFD |
