SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake August 17, 3:02am, 1999 Mw 7.4 Mw earthquake: >18,000 fatalities >300,000 homeless

SCEC Annual Meeting - ITR 09/17/022 North-Anatolian Fault, Turkey

SCEC Annual Meeting - ITR 09/17/023 West-ward propagating series of events on the North Anatolian Fault

SCEC Annual Meeting - ITR 09/17/024 ‘Domino’ effect of earthquake sequence can largely be explained by stress transfer/triggering

SCEC Annual Meeting - ITR 09/17/028 Illustration of  f (t) North Anatolian Fault 1944 Event

SCEC Annual Meeting - ITR 09/17/029 North Anatolian Fault Sequence km N

SCEC Annual Meeting - ITR 09/17/0210 Soil Amplification A 2 /A 1 = (  1 c 1 /  2 c 2 ) 1/2 A 1  1 c 1 A 2  2 c 2

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SCEC Annual Meeting - ITR 09/17/0213 Forces of Nature

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake A 14’th century mosque is surrounded by remains of collapsed houses. The apartment in the background was nearly undamaged

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SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake The most common residential structure types in the country are 2 to 5 story low-rise buildings, concrete, reinforced with straight, or in some occasions ribbed bars. Infill walls are made of unreinforced brick walls, the use of shear walls are quite rare. The floor plans are usually symmetric, incorporating 2 to 4 apartment units on each floor.

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake Many of the buildings in the area collapsed as a result of failure in beam-column connections. This was primarily due to the poor detailing in the structural design that led to insufficient amount of reinforcing in critical parts of the structure.

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake Many of the buildings the region were not built with shear walls. In many instances, the unreinforced masonry walls resisted the lateral loads. The resulting failure is also referred to as the ‘pancake effect’, in which the frame elements cannot resist lateral loads, collapsing the building at once.

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake The design of buildings constructed on the main streets were modified in order to create more open spaces in the first floor, in order to accommodate shops and stores. This was a fatal mistake, most of these buildings collapsed on their first floors, usually damaging the floors above it as well

SCEC Annual Meeting - ITR 09/17/0221 Inertial Forces F=ma Newton’s 2nd law Mass ~ Constant: increasing a -> increasing F Thus, to decrease F -> decrease m or a F inertial force: mass opposes the a in an opposite direction and proportionally to the size of a

SCEC Annual Meeting - ITR 09/17/0222 Inertial Forces F imposes strains on building’s structural elements: beams, columns, lead-bearing walls, floors, connecting elements Free-standing block: move opposite to the ground motion with F=ma Founded block: inertial force absorbed internally

SCEC Annual Meeting - ITR 09/17/0223 Resonance (dynamic amplification) Building Height Typical Natural Period V, H 2 story 0.2 seconds 5 story 0.5 seconds f 0 =V/4H 10 story 1.0 second fundamental 20 story 2.0 second resonance frequency 30 story 3.0 second 50 story 5.0 seconds

SCEC Annual Meeting - ITR 09/17/0224 Building Stiffness Taller buildings tend to be more flexible than shorter Ability to undergo distortion without complete failure Metals more ductile than stone, brick and concrete More damping -> sooner stop vibrating Added damping devices Building Ductility Building Damping

SCEC Annual Meeting - ITR 09/17/0225 Base Isolation Building Height Typical Natural Period 2 story.2 seconds 5 story.5 seconds 10 story 1.0 second 20 story 2.0 second 30 story 3.0 second 50 story 5.0 seconds

SCEC Annual Meeting - ITR 09/17/0226 Base Isolation

SCEC Annual Meeting - ITR 09/17/0227 Base Isolation

SCEC Annual Meeting - ITR 09/17/0228 Earthquake Resistant Design lengthening the building’s period of vibration

SCEC Annual Meeting - ITR 09/17/ Izmit Earthquake Lessons learned: - Building structures that comply with codes and specifications is not a requirement; it is a must. Many of the failures could have been avoided with proper design and construction. -The choice of construction site is a crucial decision in designing for earthquake resistant structures. Constructing on liquefiable sand and silt deposits requires additional measures to be taken (such as pile or flat foundations, seismic isolators. - The performance of structures depends highly on the type of structural system chosen. 95 percent of residential structures in Turkey are built with similar structural design, consisting of reinforced concrete framing. New construction methods, such as tunnel-type-molding or use of steel structures, are proven to be more effective in such damage prone areas. Such methods should be promoted and adopted.

SCEC Annual Meeting - ITR 09/17/ Mw8.0 Michoacan Earthquake  9,500 fatalities  $12-30 billion damage

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SCEC Annual Meeting - ITR 09/17/0234 Shallow structure known from the bore-hole data: 1. Lake sediments: h m, Vs m/s, 2. ‘Deep’ sedimentary basin: h m, Vs m/s