Seismic risk

Question 1

What occurred to the memphis hospital due to ground motion modelling of New Madrid zone?

Answer 1

$100M seismic refit removing 9 floors

Question 2

What affects the fatality rate of regions from eqs?

Answer 2

Population density
Bulinding style
Wealth

Question 3

What will be a more likely higher cost to more developed countries from eqs?

Answer 3

economic

Question 4

What areas are most vulnerable to earthqaukes hazards?

Answer 4

HIgh earthquake hazard and high population density

Question 5

How do the surface waves affect building stability?

Answer 5

Rayleigh waves require tensile strength
Love waves require resistance to lateral shear

Question 6

What is the ranking for building styles for safety in eqs?

Answer 6

Masonry (adobe, bricks, mortar)- very little tensile strength (wood frames improve as fibres tensile)
Concerete slabs - little tensile strength (proper ties improve)
Wood and paper - may fall down but light so wont kill (fire risk)
Steel - tensile strength

Question 7

Why is adobe a bad material in eq areas?

Answer 7

Good compressive strength but little tensile
dense and heavy so collpase dangerous

Question 8

What is the danger level of concrete structures in eqs related to?

Answer 8

Level of steel re-inforcement

Question 9

What is the issue if steel re-inforcement in buildings is poor?

Answer 9

Insuffiecnt tensile strength, resitance to shear
Use of concrete beams which are heavier and more brittle
Colmns sway apart casuing slabs to fall down - Pancaking

Question 10

What is pancaking in buildings?

Answer 10

When columns allow concrete slabs to compress layers of the building

cypress freeway - loma prieta 1989

Question 11

What is one of the best ways to increase the strength of suspended roads?

Answer 11

Column strength - having steel roads and coiled sprinf like steel to increase strength

Question 12

What is earthquake engineering?

Answer 12

Applying civil engineering to reduce life and economic losses due to eqs (mitigate seismic risk)

Question 13

What is the design problem for eq engineering?

Answer 13

Eq will usually be the most severe loading but even in active areas possibility eq might not occur in lifetime

Question 14

What % of building weight will be laterally exterend on a building during an eq?

Answer 14

25-30

Question 15

How are buildings typically deisgned to withstand eqs?

Answer 15

Building life 50 years so deisgned to withstand return of 475 (10%) but designed to damaged in a none critcal way as prohibitive would be too high

Question 16

How are buildings deisgned to cotnrol location of damage and avoid catatrophic failure?

Answer 16

No weak zones (regulairy in plan and elevation)
Connection between structural elemenrs ( anchoring of reinfoecement)
Dont deisgn areas of stress concentration
Dynaimc response (space between buildings to avoid pounding)

Question 17

What is the resonant frequency and how can it cause collpase?

Answer 17

If resonant frequency (function of height and ridifdity) is equal to frequency of ground oscillations then damage or collpase more likely

Question 18

What is an example of resonant frequency causing collapse?

Answer 18

Mexico city 85 - intermiedite hieght buildings colpased

Question 19

WHat are some exmaple of local stress points?

Answer 19

Short columns or irregular frames

Question 20

Can anything be done to mitigate surface rupture at the fault zone?

Answer 20

Zoned for parks or as streets

Question 21

Where will most damage from quake hazards be?

Answer 21

within 50km