Friday, March 25, 2011

How to Earthquake Proof Buildings


When designing earthquake safe structures the first consideration is to make the highest bit, the roof, as light as possible. This is best done with profiled steel cladding on light gauge steel Zed purlins. This can also have double skin with spacers and insulation. It can have a roof slope between 3 and 15 degrees. If it is required to have a 'flat' roof, this could be made with a galvanised steel decking and solid insulation boards, and topped with a special membrane. Even a 'flat' roof should have a slope of about 2 degrees. If it is required to have a 'flat' concrete roof, then the best solution is to have steel joists at about 2m, 6", centres, and over these to have composite style roof decking. Then an RC slab can be poured over the roof, with no propping; the slab will only be say 110mm, 4 1/2", and will weigh only about 180 kg/sqm. Such a slab will be completely bonded to the frame and will not be able to slip off, or collapse.
If the building or structure is a normal single storey, then any normal portal frame or other steel framed building, if the design and construction is competently done, will be resistant to Earthquake loads. If it is to have 2 or more stories, more needs to be done to ensure its survival in an earthquake. As with the roof, the floors should be made as light as possible. The first way to do this is to use traditional timber joists and timber or chipboard or plywood flooring. If this is done it is vital that the timber joists are firmly through bolted on the frames to avoid them slipping or being torn off. The frame needs them for stability and the floor must never fall down. A better alternative is to substitute light gauge steel Zeds for the timber joists. These can span further and are easier to bolt firmly to the framework. Then, floor-boards or tongue-and-groove chipboard can easily be screwed to the Zeds. However in Hotels, Apartment buildings, Offices and the like, concrete floors may be needed. In such cases we should reduce the spans to the spanning capacity of composite decking flooring, and pour reinforced concrete slabs onto our decking. The decking is fixed to the joists, the joists into the main beams, the main beams into the columns and the concrete is poured around all the columns. There is simply no way that such floors can fall off the frame.
Proof building diagram
Once the floors are robustly fitted to the frames, the frames themselves must be correctly designed. Please look at the diagram above.
Start at the bottom. The frame should not be built on simple pinned feet at ground level. Outside earthquake zones it is normal to build a 'nominally pinned footing' under each column. This actually gives some fixity to the base as well as horizontal and vertical support. But in an earthquake, this footing may be moving and rotating, so rather than provide a bit of fixity, it can push to left or right, or up and down, and rotate the column base, helping the building to collapse prematurely. Any pinned footing may actually be moving differently from other footings on the same building, and so not even be giving horizontal or vertical support, but actually helping to tear the building apart. So to earthquake proof the building REIDsteel would start with steel ground beams joining the feet together, and these should have moment resistance to prevent the bottoms of the columns from rotating. These ground beams may well go outside the line of the building, thus effectively reducing the height-to-width ratio as well, helping to reduce total over-turning. This ground beam may be built on pads or piles or rafts as appropriate. On loose soils, the bearing pressure should be very conservatively chosen, to minimise effect of liquefaction.
By applying earthquake engineering techniques, REIDsteel would then fit the columns to these ground beams with strong moment connections. Either the connections should be strong in both directions, or some columns designed to resist loads in one direction and others in the other direction. The columns should not be the item that fails first: the ground beam should be able to rotate and form plastic hinges before either the connection or the column fails. The reason is that a column failing could instigate a collapse; the connection failing could instigate the column failure. In comparison, the plastic hinging of the ground beam takes time, absorbs energy, and changes the resonant frequency of the frame while leaving the frame nearly full strength.
Next, REIDsteel would fix the main beams to the outer columns with full capacity joints. This will almost always mean haunched connections. Great care would be taken to consider the shear within the column at these connections. The connections should be equally strong in both up or down directions, and the bolt arrangement should never fail before the beam or the column. In extreme earthquake sway, the beams should always be able to form hinges somewhere, in one or two places, without the column with its axial load failing elastically. In this way the frame can deflect, the plastic hinges can absorb energy; the resonant frequency of the structure is altered, all without collapse or major loss of strength. All this takes a little time until the tremor passes. The inner columns do not give a lot of sway resistance, but even so, should have connections which do not fail before the beam or the column. Then, the floors are fitted, Light-weight or conventional cladding is fitted to the frames, light-weight or thin concrete roofs are fitted as described above. You have a building that will behave very well in an earthquake with significant resistance to damage.
Nothing can be guaranteed to be fully resistant to any possible earthquake, but buildings and structures like the ones proposed here by REIDsteel would have the best possible chance of survival; and would save many lives and livelihoods, providing greater safety from an earthquake.

Wednesday, March 23, 2011

Blizzards Safety

 BEFORE SEVERE WEATHER ARRIVES 

Timely preparation, including structural and non-structural mitigation measures to avoid the impacts of severe winter weather, can avert heavy personal, business and government expenditures. Experts agree that the following measures can be effective in dealing with the challenges of severe winter weather:
  • Store drinking water, first aid kit, canned/no-cook food, non-electric can opener, radio, flashlight and extra batteries where you can get them easily, even in the dark.
  • Keep cars and other vehicles fueled and in good repair, with a winter emergency kit in each.
  • Get a NOAA Weather Radio to monitor severe weather.
  • Know how the public is warned (siren, radio, TV, etc.) and the warning terms for each kind of disaster in your community; e.g.:

    • "winter storm watch" --- Be alert, a storm is likely
    • "winter storm warning" --- Take action, the storm is in or entering the area
    • "blizzard warning" --- Snow and strong winds combined will produce blinding snow, near zero visibility, deep drifts, and life-threatening wind chill--seek refuge immediately!
    • "winter weather advisory" --- Winter weather conditions are expected to cause significant inconveniences and may be hazardous, especially to motorists
    • "frost/freeze warning" --- Below freezing temperatures are expected and may cause damage to plants, crops, or fruit trees
    • "flash flood or flood watch" --- Be alert to signs of flash flooding and be ready to evacuate on a moment's notice
    • "flash flood warning" --- A flash flood is imminent--act quickly to save yourself because you may have only seconds
    • "flood warning" --- Flooding has been reported or is imminent--take necessary precautions at once
  • Know safe routes from home, work and school to high ground.
  • Know how to contact other household members through a common out-of-state contact in the event you and have to evacuate and become separated.
  • Know how to turn off gas, electric power and water before evacuating.
  • Know ahead of time what you should do to help elderly or disabled friends, neighbors or employees.
  • Keep plywood, plastic sheeting, lumber, sandbags and hand tools on hand and accessible.
  • Winterize your house, barn, shed or any other structure that may provide shelter for your family, neighbors, livestock or equipment. Install storm shutters, doors and windows; clear rain gutters; repair roof leaks; and check the structural ability of the roof to sustain unusually heavy weight from the accumulation of snow--or water, if drains on flat roofs do not work.
  • If you think you might want to volunteer in case of a disaster, now is the time to let voluntary organizations or the emergency services office know--beforehand.
DURING ANY STORM OR EMERGENCY
  • Monitor your NOAA Weather Radio or keep a local radio and/or TV station on for information and emergency instructions.
  • Have your emergency survival kit ready to go if told to evacuate.
  • If you go outside for any reason, dress for the season and expected conditions:
    For cold weather, wear several layers of loose-fitting, lightweight, warm clothing rather than one layer of heavy clothing. Outer garments should be tightly woven and water-repellent. Mittens are warmer than gloves. Wear a hat. Cover your mouth with a scarf to protect your lungs from extremely cold air. Wear sturdy, waterproof boots in snow or flooding conditions.
  • If advised to evacuate, tell others where you are going, turn off utilities if told to, then leave immediately, following routes designated by local officials.
DURING A WINTER STORM
  • Conserve fuel, if necessary, by keeping your house cooler than normal. Temporarily shut off heat to less-used rooms.
  • If using kerosene heaters, maintain ventilation to avoid build-up of toxic fumes. Keep heaters at least three feet from flammable objects. Refuel kerosene heaters outside.
  • Avoid travel if possible. If you must travel, do so during daylight. Don't travel alone. Stay on main roads, and keep others informed of your schedule.
IF A BLIZZARD TRAPS YOU IN YOUR CAR
  • Pull off the road, set hazard lights to flashing, and hang a distress flag from the radio aerial or window. Remain in your vehicle; rescuers are most likely to find you there.
  • Conserve fuel, but run the engine and heater about ten minutes each hour to keep warm, cracking a downwind window slightly to prevent carbon monoxide poisoning. Exercise to maintain body heat but don't overexert. Huddle with other passengers and use your coat for a blanket.
  • In extreme cold use road maps, seat covers, floor mats, newspapers or extra clothing for covering--anything to provide additional insulation and warmth.
  • Turn on the inside dome light so rescue teams can see you at night, but be careful not to run the battery down. In remote areas, spread a large cloth over the snow to attract the attention of rescue planes.
  • Do not set out on foot unless you see a building close by where you know you can take shelter.
  • Once the blizzard is over, you may need to leave the car and proceed on foot. Follow the road if possible. If you need to walk across open country, use distant points as landmarks to help maintain your sense of direction.
AFTER THE STORM
  • Report downed power lines and broken gas lines immediately.
  • After blizzards, heavy snows or extreme cold, check to see that no physical damage has occurred and that water pipes are functioning. If there are no other problems, wait for streets and roads to be opened before you attempt to drive anywhere.
  • Check on neighbors, especially any who might need help.
  • Beware of overexertion and exhaustion. Shoveling snow in extreme cold causes many heart attacks. Set your priorities and pace yourself after any disaster that leaves you with a mess to clean up. The natural tendency is to do too much too soon.

Tips for avalanche survival


Tips for avalanche survival

Before crossing a slope where there is any possibility of an avalanche, fasten all your clothing securely to keep out snow. Loosen your pack so that you can slip out of it with ease and remove your ski pole straps. Make sure that your avalanche beacon is on and switched to "transmit" rather than "receive." Cross the slope one at a time to minimize danger.

If you are caught in an avalanche

Yell and let go of ski poles and get out of your pack to make yourself lighter. Use "swimming" motions, thrusting upward to try to stay near the surface of the snow. When avalanches come to a stop and debris begins to pile up, the snow can set as hard as cement. Unless you are on the surface and your hands are free, it is almost impossible to dig yourself out. If you are fortunate enough to end up near the surface (or at least know which direction it is), try to stick out an arm or a leg so that rescuers can find you quickly.
If you are in over your head (not near the surface), try to maintain an air pocket in front of your face using your hands and arms, punching into the snow. When an avalanche finally stops, you may have only a few seconds before the snow sets up and hardens. Many avalanche deaths are caused by suffocation, so creating an air space is one of the most critical things you can do. Also, take a deep breath to expand your chest and hold it; otherwise, you may not be able to breathe after the snow sets. To preserve air space, yell or make noise only when rescuers are near you. Snow is such a good insulator they probably will not hear you until they are practically on top of you.
Above all, do not panic. Keeping your breathing steady will help preserve your air space and extend your survival chances. If you remain calm, your body will be better able to conserve energy.

Rescuing a victim

Try to watch the victim as they are carried down the slope, paying particular attention to the point you last saw them. After the avalanche appears to have finished and settled, wait a minute or two and observe the slope carefully to make sure there is no further avalanche danger. If some danger does still exist, post one member of your party in a safe location away from the avalanche path to alert you if another avalanche falls.
When traveling with a large party, you may want to send someone for help immediately while the rest of you search. If you are the only survivor, do a quick visual search. If you don't see any visual clues, and you don't have transceivers, then go for help.
Begin looking for clues on the surface (a hand or foot, piece of clothing, ski pole, etc.), beginning with the point where they were last seen. As you move down the slope, kick over any large chunks of snow that may reveal clues. Since equipment and items of clothing may be pulled away from a victim during an avalanche, they may not indicate their exact location, but can help determine the direction the avalanche carried them. Mark these spots as you come across them. Be sure that all rescuers leave their packs, extra clothing, etc., away from the search area so as not to clutter or confuse search efforts.
Once the victim is found, it is critical to unbury them as quickly as possible. Survival chances decrease rapidly depending on how long a victim remains buried. Treat them for any injuries, shock, or hypothermia if necessary.
If you lost sight of the victim early during the avalanche, or if there are no visible clues on the surface, mark where the victim was last seen. Look at the path of the snow and try to imagine where they might have ended up. For those wearing avalanche transceivers, switch them to "receive" and try to locate a signal.
For those using probes, begin at the point the victim was last seen at. Or if you have a good idea of where they were buried, begin in that area. Stand in a straight line across the slope, standing shoulder to shoulder. Repeatedly insert the probes as you move down slope in a line. Pay particular attention to shallow depressions in the slope and the uphill sides of rocks and trees, since these are terrain traps where they may have been buried.
It may be necessary to probe certain areas more than once if you don't locate the victim the first time around, but this takes more time and decreases the victim's chances for survival. Similar to using transceivers, this method of rescue is much more effective if those involved have experience or have practiced finding buried victims using probes.
After searching for clues, or using transceivers and/or probes, still does not reveal the location of the victim, it may be time to rely on outside help. Nearby ski resorts will be staffed with personnel experienced to handle these situations. They will have equipment to locate the victims and dig them out (if your party did not bring shovels or probes), and they may also have avalanche dogs that can help find victims. Ski area patrollers will also have first aid equipment, but unfortunately, by the time they can usually reach out-of-bounds avalanche accidents, too much time has elapsed to save the victim.

Monday, March 21, 2011

Natural disaster


A natural disaster is the effect of a natural hazard (e.g., flood, tornado, hurricane, volcanic eruption, earthquake, or landslide). It leads to financial, environmental or human losses. The resulting loss depends on the vulnerability of the affected population to resist the hazard, also called their resilience. This understanding is concentrated in the formulation: "disasters occur when hazards meet vulnerability." A natural hazard will hence never result in a natural disaster in areas without vulnerability, e.g. strong earthquakes in uninhabited areas. The termnatural has consequently been disputed because the events simply are not hazards or disasters without human involvement. A concrete example of the division between a natural hazard and a natural disaster is that the 1906 San Francisco earthquake was a disaster, whereas earthquakes are a hazard. This article gives an introduction to notable natural disasters.


Lists of natural disasters

·                  Avalanches
·                  Blizzards
·                  Contractible diseases
·                  Cyclones
·                  Earthquakes
·                  Famines
·                  Floods and landslides
·                  Heat waves
·                  Limnic eruptions
·                  Meteorites
·                  Storms (non-cyclone)
·                  Tornadoes
·                  Tsunami
·                  Volcanic eruptions
·                  Wildfires and bushfires