The beam is made of elastic perfectly plastic material. Determine the maximum elastic moment and the plastic moment that can be applied to the cross section. Take a = 50 mm and sY = 230 MPa.
4/12/16 Water 97.5% of water is seawater o 2.0% is ice o .5% is freshwater o this .0001% produces 100% of our water for drinking and irrigation water use per person is rising two times faster than population growth abundance of water is not the issue o where it is and when it is needed is the problem by 2020, more than 33% of all human beings will live her o there is not enough fresh water o 25% already do 1/5 people on planet are living on less water a day than the flush of a toilet o video: water is imperative, lack of it causes poverty and sickness by 2020, water use in U.S will exceed supply by 13% o this projection has 3 assumptions 1. assumes stable population (no growth) 2. assumes stable climate (no global warming) 3. assumes average rainfall (no drought) Water “rules” water is always recycled water is always in motion surface and subsurface waters are tightly linked Water budget 1. storage (reserves) surface (lakes) subsurface (groundwater) 2. inputs (deposits) surface (rainfall) subsurface (groundwater) 3. outputs (withdraws) surface (drawdown, siphon off) subsurface (pump out) evaporation/transportation Where does our water come from 50% of U.S population relies on groundwater as its primary source for drinking water GA’s freshwater getting further from freshwater; water supply is going down Oceanic Saltwater Intrusion when you run out of freshwater from ocean CA drought People couldn’t water their grass anymore Video: fun animated video about water use Video 2: water war: china vs. Vietnam over use of water from Mekong GA vs. AL vs. FL ACF river basin o Appalochia, Chattahoochee, Flint river o Usage based on population GA: 87% AL 8% FL 5% o If it was based on land area of drainage basin GA: 51% AL: 38% FL: 11% Video: chemicals seeping in water in West Virginia Video 2: flint Michigan Mississippi River Drainage Basin 40,000 square miles herbicides, pesticides, fungicides, fertilizer huge dead zone here, Gulf of Mexico Dead Zone sucks up oxygen, nothing can live here also present in Nile, Amazon, Mekong, Ganges, Colorado agal blooms in Lake Erie Florida bad news for their water Sustainable Water use, balance budget 1. increase reserves 2. reduce withdraws a. conservation b. recycle c. landscape architecture 3. more offchannel reservoirs 4. change price of water a. desalination is 15.50 a pint an ancient reservoir Mesa Verde distribution of water on earth changed significantly 4/14/16 In our attempts to control water, we are making things worse Ex: Mississippi Flood o Video: Brent Blackwelder said flood was manmade o U.S army engineers said it was rain o Either way, dams make things worse Flash floods are super dangerous Seasonal Photosynthesis of Corals in Florida Keys 19921993 measured amount of oxygen in them, when warmer there were higher amounts of o2 when you put coral bleaching in, photosynthesis goes down because of lack of algae on September 10 , 1993, coral photosynthesis stopped but restoration did not Mississippi River Flood caused the cease on September 10 th o Because herbicides stop photosynthesis, but not respiration o Atrazine powerful herbicide From farms, fields, factories, flood washed the herbicides to the Gulf of Mexico Coral reefs more than 1,000 miles away were effected LAW: WE ALL LIVE DOWNSTREAM Stream invertebrates used to determine health of U.S rivers Colorado River Delta; all water is used before ocean Aquifers When you pump them dry…. o Land subsidence occurs o Ex: Winter Park, FL o Kentucky with fancy cars Environmental mismanagement causes this Forests Last of the Mohicans forest filmed at is destroyed for movie Environmental Decision making Location of power Extent of political influence Fallacy of “jobs versus environment” What to do o 1998 Forest Summit (Pacific Northwest, Atlantic Southeast) Forest Loss in Haiti logging and rubber plantations leads to deforestation political instability reduced tourism which lead to poverty by 1990 most of Haiti was deforested Values of Forests forests contain 75% of world biodiversity ecosystem services o flood prevention o carbon storage o air and water quality wood products: o 3.4 billion cubic meters of wood per year o proportions vary by region o 53% for fuel forests also produce: o rubber o syrup o medicine Deforestation 2% of forests disappear every year pace quickening causes: o agricultural expansion o cleaning forests Solutions Haiti is past conservation, must restore forests Communitybased initiative shows promise As of 2011, 8 million trees planted by 650 farmers