How Have Earthquakes Shaped Civil Engineering

HOW HAVE EARTHQUAKES SHAPED CIVIL ENGINEERING As the earth vibrates, all buildings on the ground surface will respond to that vibration in varying degrees When the base of the building suddenly • Structural elements, such as walls, beams moves to the right, the building moves to the left relative to the base, as if it was being pushed to the left by an unseen force called inertia and columns that were bearing only vertical loads before the earthquake, now have to carry horizontal bending and shearing effects as well • If the building material is weak in tension, such as brick or stone masonry, cracking Occurs that reduces the effective area for resisting bending movement As the base of a building moves the superstructure including its contents tends to shake and vibrate from the position of rest STATES WITH THE MOST QUAKES Alaska accounts for more than ALAS K A 50% of all U.S. earthquakes 2,600 quakes in 2014 Alaska had more than A recent study found that more than 143 MILLION AMERICANS live in earthquake-prone regions in the lower 48 states The study also revealed more than and nearly more than 6,000 800 20,000 fire stations hospitals public and private schools are built on shaky ground Researchers have also calculated potential economic losses from damaged buildings, such as homes, hospitals, schools and fire stations: $4.5 BILLION $4.5B Central and eastern states have seen a sharp rise in earthquakes over the past few years CENTRAL STATE EASTERN STATE AVG. EARTHQUAKES PER YEAR YEAR MAGNITUDE 21 3+ 99 3+ 659 3+ 1973-2008 2009-2013 2014 The spike is due to a rise in quakes caused by human activity – usually fracking, enhanced oil recovery, saltwater disposal, or wastewater injections INDUCED SEISMICITY A recent US Geological Survey report confirmed that drilling for oil and gas triggered man-made earthquakes in eight states: Alabama, Arkansas, Colorado, Kansas, New Mexico, Ohio, Oklahoma and Texas From 1975 to 2008: Oklahoma averaged a handful of earthquakes of magnitude 3 or greater AVG. EARTHQUAKES PER YEAR YEAR MAGNITUDE 20 3+ 2009 60 5.7 2011 OKLAHO MA 585 3+ 2014 Central Oklahoma, without any major faults, is now more seismically active than San Francisco DISASTER AND INNOVATION ALASKA 1964 GREAT EARTHOUAKE ALASKA FATALITIES: 131 PROPERTY LOSS: $2.3B 9.2 6 MAGNITUDE (in 2013 dollars; equivalent to $311 million in 1964) DURATION: 3 MINS Anchorage, about 120 kilometers (75 miles) northwest of the epicenter, sustained the most severe damage to property The U.S. Geological Survey National Seismic Hazard Maps began after the Alaska Earthquake USGS ZUSGS science for a changing world Production of the USGS [U.S. Geological Survey] National Seismic Hazard Maps These maps are used in developing building codes and helping ensure that earthquake-resistant buildings are built in areas at risk from earthquakes 3000 DEAD: $300,000,000 LOST OBLITERATED NIGHT BDITION WeetherSS THE CINCINNATI POST 1906 The Evening Times EARTHQUAKE LEVELS SAN FRANCISCO SAN FRAN SAN FRANCISCO A THOUSAND PERSONS REPORTED TO BE DEAD Jity is in Plames and Piremen Helples Water Mains Burst, Lenving Buing ka Dres Merey Seven Mili Dullar City Hall a Mass of Plames and lels EARTHOUAKE NO POWER ABLF TO CHECK FL/ SAN FRANCISCO FATALITIES: 3,000 7.8 . PROPERTY LOSS: $13.6B (in 2014 dollars; equivalent to $540 million in 1906) The earthquake damaged buildings and structures in all parts of the city and county of San Francisco MAGNITUDE DURATION: 1 MIN California was the birthplace of seismic regulations for buildings in the U.S. in the wake of the 1906 earthquake The building codes in San Francisco were radically revised after the 1906 earthquake to improve the strength and safety of all new buildings SOUTH NAPA EARTHOUAKE August 24, 2014 This magnitude 6 earthquake was the strongest earthquake in 25 years in Northern Çalifornia's Bay Area NAPACA 94559 SOUTH N A PLA The post office building cracked, the local hardware store was destroyed with layers of shelves that fell and broke the windows, and multiple buildings fell apart 6.0 Buildings built before 1950 -– from historic landmarks to modest homes and businesses were the hardest hit of alI MAGNITUDE Schools performed well structurally, but they experienced nonstructural damage that could have been life threatening had the earthquake occurred during school hours The earthquake highlighted the danger posed by pendant light fixtures, unrestrained bookcases, storage units, and similar components that overturned in the earthquake, often striking tables and desks The 2014 South Napa earthquake demonstrated the vulnerability of URM (unreinforced masonry) buildings to damage in moderate ground shaking URM buildings typically have brick or stone masonry exterior walls with wood framed floors and roofs The ends of the floor and roof joists bear in pockets in the walls and derive their vertical support there. The City of Napa adopted a URM [Unreinforced Masonry Structures] ordinance in 2006 It gave property owners two years to survey and assess their buildings and develop a plan for mitigating the seismic risk CITYOF NAPA SOLUTIDNS TECHNDLOGY AND CIVIL ENGINEERS WILL USE TO KEEP BUILDINGS SAFE DURING FUTURE EARTHQUAKES Earthquake simulators, also known as shake tables, are a valuable tool for the dynamic and seismic behavior assessment of civil engineering structures Research using shake tables has been oriented mainly for the ultimate behavior of steel and RC [reinforced concrete] building structures, structural elements (with a clear emphasis on RC and masonry walls, RC frames with infills and dissipating devices) and global models of structures at smaller scales Civil engineers use complex analytical and numerical models to predict how bridges, buildings and other structures will behave during earthquakes and to design earthquake-resistant structures To meet this challenge and increase the accuracy of earthquake simulations, Lehigh University established the Real-Time Multi-Directional (RTMD) earthquake simulation facility at the Advanced Technology for Large Structural Systems (ATLSS) Engineering Research Center • Housed in a repurposed steel plant, it includes a reaction wall and hydraulic actuators capable of applying force to a structure from three directions • It has a floor area of approximately 100 feet by 40 feet, and reaction walls up to 50 feet high • It has been used to test bridge decks, shear walls, and four-story buildings Researchers use Simulink® to develop models of large-scale structures and the actuator controllers that replicate seismic activity • Data gathered from the sensors is post processed in MATLAB ®. spec TargetTM enables the team to conduct real-time hybrid tests that combine physical structures with analytical models Hybrid tests combine experimental techniques carried out in earthquake engineering labs with numerical simulations • The technique was developed by researchers at The State University of New York at Buffalo (UB) and Japan's Kyoto University and first tested in 2009 • The main goal is to test the nature of structural collapse NETWORK FOR EARTHQUAKE ENGINEERING SIMULATION The NEES is a network of 15 large-scale, experimental sites that feature tools such as shake tables, centrifuges that simulate earthquake effects, unique laboratories, a tsunami wave basin and field-testing equipment NEES With these tools, engineers and students from all parts of the country can collaborate on multi-site experiments using simulators that generate earthquake effects strong enough to bring down full-sized buildings. Progress: From 1811 to 1960, From 1960 to present 3,263 people 409 died in earthquakes in people have died. the United States. 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