- Hurricanes are giant, spiraling tropical storms that can pack wind speeds of over 160 miles an hour and unleash more than 2.4 trillion gallons of rain a day. These same tropical storms are known as cyclones in the northern Indian Ocean and Bay of Bengal, and as typhoons in the western Pacific Ocean.
- The Atlantic Ocean’s hurricane season peaks from mid-August to late October and averages five to six hurricanes per year.
- When they come onto land, the heavy rain, strong winds and heavy waves can damage buildings, trees and cars. The heavy waves are called a storm surge.
- Storm surges are very dangerous and a major reason why you MUST stay away from the ocean during a hurricane warning or hurricane.
- Hurricanes rotate in a counter-clockwise direction around the eye. The rotating storm clouds create the "eye wall”, which is the most destructive part of the storm.
- The difference between a tropical storm and a hurricane is wind speed – tropical storms usually bring winds of 36-47 miles per hour, whereas hurricane wind speeds are over 74 miles per hour.
- Hurricanes are classified into five categories, based on their wind speeds and potential to cause damage.
- Hurricanes are named to help us identify and track them as they move across the ocean. For Atlantic Ocean hurricanes, the names may be French, Spanish or English, since these are the major languages bordering the Atlantic Ocean where the storms occur.
- Sometimes names are "retired" if a hurricane has been really big and destructive. It's like when a sports jersey or number is retired after a really great athlete leaves a sport. Retired names include Katrina, Andrew and Mitch.
- The costliest hurricane to hit landfall was Hurricane Katrina, a Category 5 storm that slammed Louisiana in August of 2005. Damages cost an estimated $91 billion.
- The deadliest U.S. hurricane on record was a Category 4 storm that hit the island city of Galveston, Texas, on September 8th, 1900. Some 8,000 people lost their lives when the island was destroyed by 15-foot waves and 130-mile-an-hour winds.
Wednesday, June 12, 2013
Monday, June 3, 2013
Ever think about the bridges you cross on your way to work? So I came across this article today, and I immediately started reminiscing this nursery rhyme... Here is an image for dramatic effect:
On a serious note, how many bridges have fallen? And how many are at the risk of collapsing? Hundreds? I read an article that claims thousands are at the risk of giving in . . .
Thousands of Bridges at Risk of Freak Collapse
By: Mike Baker and Joan Lowy - ASSOCIATED PRESS
The most famous failure of a fracture critical bridge was the collapse of the I-35W bridge in Minneapolis during rush hour on Aug. 1, 2007, killing 13 people and injuring more than 100 others.
The crossings are kept standing by engineering design, not supported with brute strength or redundant protections like their more modern counterparts. Bridge regulators call the more risky spans "fracture critical," meaning that if a single, vital component of the bridge is compromised, it can crumple.
Those vulnerable crossings carry millions of drivers every day. In Boston, a six-lane highway 1A near Logan airport includes a "fracture critical" bridge over Bennington Street. In northern Chicago, an I-90 pass that goes over Ashland Avenue is in the same category. An I-880 bridge over 5th Avenue in Oakland, Calif., also is on the list.
Also in that category is the Interstate 5 bridge over the Skagit River north of Seattle, which collapsed into the water after officials say an oversized truck load clipped the steel truss.
Public officials have focused in recent years on the desperate need for money to repair thousands of bridges deemed structurally deficient, which typically means a major portion of the bridge is in poor condition or worse. But the bridge that collapsed May 23 is not in that deficient category, highlighting another major problem with the nation’s infrastructure: Although it’s rare, some bridges deemed to be fine structurally can still be crippled if they are struck hard enough in the wrong spot.
"It probably is a bit of a fluke in that sense," said Charles Roeder, a professor of civil and environmental engineering at the University of Washington.
While the I-5 truck’s cargo suffered only minimal damage, it left chaos in its wake, with two vehicles catapulting off the edge of the broken bridge into the river below. Three people involved escaped with non-life threatening injuries.
The most famous failure of a fracture critical bridge was the collapse of the I-35W bridge in Minneapolis during rush hour on Aug. 1, 2007, killing 13 people and injuring more than 100 others. The National Transportation Safety Board concluded that the cause of the collapse was an error by the bridge’s designers — a gusset plate, a key component of the bridge, was too thin. The plate was only half of the required one-inch thickness.
Because the bridge’s key structures lacked redundancy, where if one piece fails, there is another piece to prevent the bridge from falling, when the gusset plate broke, much of the bridge collapsed.
Mark Rosenker, who was chairman of the NTSB during the I-35W bridge investigation, said the board looked into whether other fracture critical bridges were collapsing. They found a few cases, but not many, he said.
"Today, they’re still building fracture critical bridges with the belief that they’re not going break," Rosenker said.
Fracture critical bridges, like the I-5 span in Washington, are the result of Congress trying to cut corners to save money rather than a lack of engineering know-how, said Barry B. LePatner, a New York real estate attorney and author of "Too Big to Fall: America’s Failing Infrastructure and the Way Forward."
Approximately 18,000 fracture critical bridges were built from the mid-1950s through the late 1970s in an effort to complete the nation’s interstate highway system, which was launched under President Dwight Eisenhower, LePatner said in an interview. The fracture critical bridge designs were cheaper than bridges designed with redundancy, he said.
Thousands of those bridges remain in use, according to an AP analysis.
"They have been left hanging with little maintenance for four decades now," he said. "There is little political will and less political leadership to commit the tens of billions of dollars needed" to fix them.
There has been little focus or urgency in specifically replacing the older "fracture critical" crossings, in part because there is a massive backlog of bridge repair work for thousands of bridges deemed to be structurally problematic. Washington state Rep. Judy Clibborn, a Democrat who leads the House transportation committee, has been trying to build support for a tax package to pay for major transportation projects in the state. But her plan wouldn’t have done anything to revamp the bridge that collapsed.
National bridge records say the I-5 crossing over the Skagit River had a sufficiency rating of 57.4 out of 100 — a score designed to gauge the ability of the bridge to remain in service. To qualify for federal replacement funds, a bridge must have a rating of 50 or below. A bridge must have a sufficiency rating of 80 or below to qualify for federal rehabilitation funding.
Hundreds of bridges in Washington state have worse ratings than the one that collapsed, and many around the country have single-digit ratings.
Clibborn said the Skagit River crossing wasn’t even on the radar of lawmakers because state officials have to prioritize by focusing on bridges with serious structural problems that are at higher risk of imminent danger.
Along with being at risk of a fatal impact, the I-5 bridge was deemed to be "functionally obsolete," which essentially means it wasn’t built to today’s standards. Its shoulders were narrow, and it had low clearance.
There are 66,749 structurally deficient bridges and 84,748 functionally obsolete bridges in the United States, including Puerto Rico, according to the Federal Highway Administration. That’s about a quarter of the 607,000 total bridges nationally. States and cities have been whittling down that backlog, but slowly. In 2002, about 30 percent of bridges fell into one of those two categories.
Spending by states and local government on bridge construction adjusted for inflation has more than doubled since 1998, from $12.3 billion to $28.5 billion last year, according to the American Road and Transportation Builders Association. That’s an all-time high.
"The needs are so great that even with the growth we’ve had in the investment level, it’s barely moving the needle in terms of moving bridges off these lists," said Alison Premo Black, the association’s chief economist.
There is wide recognition at all levels of government that the failure to address aging infrastructure will likely undermine safety and hinder economic growth. But there is no consensus on how to pay for improvements. The federal Highway Trust Fund, which provides construction aid to states, is forecast to go broke next year. The fund gets its revenue primarily from federal gas and diesel taxes. But revenues aren’t keeping up because people are driving less and there are more fuel-efficient cars on the road.
Neither Congress nor the White House has shown any willingness to raise federal gas taxes, which haven’t been increased since 1993. Many transportation thinkers believe a shift to taxes based on miles traveled by a vehicle is inevitable, but there are privacy concerns and other difficulties that would preclude widespread use of such a system for at least a decade.
Transportation spending got a temporary boost with the economic stimulus funds approved by Congress after President Barack Obama was elected. Of the $27 billion designated for highway projects under the stimulus program, about $3 billion went to bridge projects, Black said.
States are looking for other means to raise money for highway and bridge improvements, including more road tolls, dedicating a portion of sales taxes to transportation and raising state gas taxes. Clibborn, the Washington state lawmaker, has proposed a 10-cent gas hike to help pay for projects, though the effort has been held up by a dispute over how to rebuild the Columbia River bridge connecting Vancouver, Wash., and Portland, Ore.
"We can’t possibly do it all in the next 10 years, but we’re going to do the first bite of the apple," Clibborn said.
Region: National Edition | StoryID: 20518 | Published On: 6/3/2013
Saturday, March 23, 2013
Following is a list of various types of floors and where you can install them.
- Solid wood floors can be installed above grade (ground level), but not below. The preferred subfloor is 3/4-inch CD grade exterior (CDZ) plywood. You can also use 3/4-inch Oriented Strand Board (OSB) underlayment, 5/8-inch CDX, or tongue-and-groove subflooring.
- Parquet floors can be installed above grade, but not below. The preferred subfloors are 3/4-inch CDX plywood or 3/4-inch OSB. You can also apply parquet over 5/8-inch CDX or existing solid wood flooring.
- Engineered wood can be installed above or below grade. Recommendations on use in bathrooms varies by manufacturer. This cannot be installed on moist or damp floors. If it is applied over a crawlspace, there must be at least 24 inches between the bottom of the joists and the ground.
- Laminate floors can be installed above or below grade and over radiant heat. Recommendations on use in bathrooms varies by manufacturer. Laminate can go over almost any subfloor, including concrete slabs, ceramic tile, stone, vinyl sheet and tile, chipboard, particleboard, and terrazzo. If installed over a crawlspace, there must be at least 24 inches between the bottom of the joists and the ground.
- Sheet vinyl can be installed above or below grade over existing sheet vinyl, linoleum, tile, new plywood, concrete, ceramic tile, or marble. Do not apply over lauan. Some plywoods are made especially to be used as underlayments for vinyl.
- Vinyl tile is not recommended below grade. Install over smooth, single-layer vinyl floors that are firmly attached, dry concrete, and wood floors with a plywood overlay. Do not apply over lauan.
- Ceramic and stone can be installed above or below grade and over radiant heat. Suitable subfloors include cement backerboard, or concrete. They cannot be installed over moist or damp floors.
- Carpeting can go over almost any subfloor. If planning to use it below grade, make sure the carpet you have in mind is suitable.
Monday, March 18, 2013
... in Steel Frame
- The raw materials for steel are iron ore, coal, limestone, air, and water. The ore, coal, and limestone are minerals whose mining and quarrying cause disruption of land and loss of wildlife habitat, often coupled with pollution of streams and rivers. Coal, limestone, and low-grade iron ore are plentiful, but high-grade iron ore has been depleted in many areas of the earth.
- Supplies of some alloying metals, such as manganese, chromium, and nickel, are becoming depleted.
- The manufacture of a ton of steel from iron ore by the basic oxygen process consumes 3170 pounds of ore, 300 pounds of limestone, 900 pounds of coke (made from coal), 80 pounds of oxygen, and 2575 pounds of air. In the process, 4550 pounds of gaseous emissions are given off, and 600 pounds of slag and 50 pounds of dust are generated. Further emissions emanate from the process of converting coal to coke.
- The steel industry has worked hard to reduce pollution of air, water, and soil, but much work remains to be done.
- The embodied energy of steel produced from ore is about 19,200 BTU/pound.
- Most structural steel in North America is made from recycled scrap; its embodied energy is only about 39 percent of that of steel made from ore.
- Sixty-six percent of all steel in eventually recycled, which is a very high rate. In a recent 10-year period, 1.2 trillion tons of steel were recycled worldwide.
- Steel fabrication and erection are relatively clean, efficient processes, although the paints and oils used on steel members can cause air pollution.
- Steel frames are light in weight as compared to concrete and masonry frames that would do the same job. This means that a steel building generally has smaller foundations and requires less excavation work.
- Some spray-on fireproofing materials can pollute the air with stray fibers.
- Steel framing, if protected from water and fire, will last for many generations with little or no maintenance.
- Steel exposed to weather needs to be repainted periodically unless it is galvanized or given a long-lasting polymer coating.
- Steel framing members in building walls and roofs should be thermally broken or insulated in such a way that they do not conduct heat between indoors and outdoors.
- When a steel building frame is demolished, its material is almost always recycled.
- Steel seldom causes indoor air quality problems, although surface oils and protective coating sometimes outgas and cause occupant discomfort.
Tuesday, January 29, 2013
After researching the history of clay brick, it has been told that the first brick probably was made in the Middle East, between the Tigris and Euphrates rivers, in what is now Iraq. Early builders here relied on the abundant natural materials to make their sun-baked bricks. However, these were of limited use because they lacked durability and couldn’t be used outdoors. Exposure to the elements caused them to disintegrate. The Babylonians, who later dominated Mesopotamia, were the first to fire bricks, from which many of their tower-temples were constructed.
From the Middle East the art of brickmaking spread west to what is now Egypt and east to Persia and India. Although the Greeks, having a plentiful supply of stone, did not use much brick, evidence of brick kilns and structures remains throughout the Roman Empire. However, with the decline and fall of Rome, brickmaking in Europe soon diminished. It did not resume until the 1200s, when the Dutch made bricks that they seem to have exported to England. In the Americas, people began to use brick during the sixteenth century. It was the Dutch, however, who were considered expert craftsmen.
Prior to the mid-1800s, people made bricks in small batches, relying on relatively inefficient firing methods. One of the most widely used was an open clamp, in which bricks were placed on a fire beneath a layer of dirt and used bricks. As the fire died down over the course of several weeks, the bricks fired. Such methods gradually became obsolete after 1865, when the Hoffmann kiln was invented in Germany. Better suited to the manufacture of large numbers of bricks, this kiln contained a series of compartments through which stacked bricks were transferred for pre-heating, burning, and cooling.
Brickmaking improvements have continued into the twentieth century. Improvements include rendering brick shape absolutely uniform, lessening weight, and speeding up the firing process. For example, modern bricks are seldom solid. Some are pressed into shape, which leaves a depression, on their top surface. Others are extruded with holes that will later expedite the firing process by exposing a larger amount of surface area to heat. Both techniques lessen weight without reducing strength.
However, while the production process has definitely improved, the market for brick has not. Brick does have the largest share of the opaque materials market for commercial building, and it continues to be used as a siding material in the housing industry. However, other siding materials such as wood, stucco, aluminum, plaster, and vinyl are strong competitors because they cost up to 50 percent less, and some (notably stucco and plaster) offer built-in insulation.
To produce brick, the raw materials are first crushed and ground in a jaw crusher. Next, the ingredients are formed using one of several methods. In extrusion, the pulverized ingredients are mixed together with water, passed into a de-airing chamber (to prevent cracking), compacted, and extruded out of a die of the desired shape.
|The ancient Jetavanaramaya stupa in Anuradhapura, Sri Lanka is one of the largest brick structures in the world.|
|The world's highest brick tower of St. Martin's Church is in Landshut, Germany, completed in 1500.|
|The historic brick street lays in Natchitoches, Louisiana.|
|The Roman Basilica Aula Palatina in Trier, Germany, was built with fired bricks in the 4th century, as an audience hall for Constantine I.|
|Malbork Castle is the biggest brick castle in the world.|
|The brickwork of Shebeli Tower in Iran displays 12th century craftsmanship.|
According to the U.S. Industrial Outlook, the use of brick as a siding material for single-family homes dropped from 26 percent in 1984 to 17 percent in 1989. Currently, the use of brick has remained steady, at around seven to nine billion a year, down from the 15 billion used annually during the early 1900s. In an effort to increase demand, the brick industry continues to explore alternative markets and to improve quality and productivity. Fuel efficiency has also improved, and by the year 2025 brick manufacturers may even be firing their brick with solar energy. However, such changes in technology will occur only if there is still a demand for brick.
Even if this demand continues, the brick industry both here and abroad faces another challenge: it will soon be forced to comply with environmental regulations, especially in the area of fluorine emissions. Fluorine, a byproduct of the brickmaking process, is a highly reactive element that is dangerous to humans. Long-term exposure can cause kidney and liver damage, digestive problems, and changes in teeth and bones, and the Environmental Protection Agency (EPA) has consequently established maximum exposure limits. To lessen the dangers posed by fluorine emissions, brickworks can install scrubbers, but they are expensive. While some plants have already installed such systems, the U.S. brick industry is trying to play a more important role in developing less expensive emissions testing methods and establishing emission limits. If the brick industry cannot persuade federal regulators to lower their requirements, it is quite possible that the industry could shrink in size, as some companies cannot afford to comply and will go out of business.
Tuesday, January 8, 2013
... in Brick Masonry Construction
- Clay and shale, the raw materials for bricks, are plentiful. They are usually obtained from open pits, with the attendant disruption of drainage, vegetation, and wildlife habitat.
- Because of the energy used in its firing, brick is a relatively energy-extensive product. The energy embodied in an average brick is 14,300 BTU. The usual energy sources for brick kilns are oil, gas, or coal. Air pollution can result from improperly regulated kilns.
- Clay and shale are found almost everywhere. The majority of bricks come from regional plants, which reduces the energy needed to ship them.
- Bricks last a very long time and usually an be recycled when a building is demolished.
- Brick masonry is not associated with indoor air quality problems.
- The thermal mass effect of brick masonry can be a useful component of fuel-saving natural heating and cooling strategies such as solar heating and nighttime cooling.
- Mortar is made of minerals that are generally abundant in the earth. Portland cement and lime are energy-intensive products.
- Relatively small amounts of waste are generated on a construction site during the construction of a brick building, including partial bricks, unsatisfactory bricks, and unused mortar. These wastes generally go into landfills or are buried on the site.
- When a brick building is demolished, the bricks may be cleaned of mortar and reused. However, the more usual practice is to dump the bricks and mortar in a landfill or to use them as fill on a construction site.
What is sustainability?