Science Daily (Mar. 9, 2009) Researchers at the University of Michigan simulated an off-the-charts earthquake in a laboratory to test their new technique for bracing high-rise concrete buildings. Their technique passed the test, withstanding more movement than an earthquake would typically demand.
The engineers used steel fiber-reinforced concrete to develop a better kind of coupling beam that requires less reinforcement and is easier to construct. Coupling beams connect the walls of high rises around openings such as those for doorways, windows, and elevator shafts. These necessary openings can weaken walls.
"We simulated an earthquake that is beyond the range of the maximum credible earthquake and our test was very successful. Our fiber-reinforced concrete beams behaved as well as we expected they would, which is better than the beams in use today," said James Wight, the Frank E. Richart Jr. Collegiate Professor in the U-M Department of Civil and Environmental Engineering.
Working with Wight on this project are Gustavo Parra-Montesinos, an associate professor in the Department of Civil and Environmental Engineering, and Remy Lequesne, a doctoral student in the same department.
Today, coupling beams are difficult to install and require intricate reinforcing bar skeletons. The U-M engineers created a simpler version made of a highly flowable, steel fiber-reinforced concrete.
"We took quite a bit of the cumbersome reinforcement out of the design and replaced it with steel fibers that can be added to the concrete while it's being mixed," Parra-Montesinos said. "Builders could use this fiber-reinforced concrete to build coupling beams that don't require as much reinforcement."
The engineers envision that their brand of beam would be cast off the construction site and then delivered. Nowadays, builders construct the beams, steel skeletons and all, bit by bit as they're building skyscrapers.
Their fiber-reinforced concrete has other benefit s as well.
"The cracks that do occur are narrower because the fibers hold them together," Parra-Montesinos said.
The fibers are about one inch long and about the width of a needle.
The engineers performed their test in December on a 40-percent replica of a 4-story building wall that they built in the Structures Laboratory. They applied a peak load of 300,000 pounds against the building, pushing and pulling it with hydraulic actuator s.
To quantify the results, they measured the building's drift, which is the motion at the top of the building compared with the motion at the base. In a large earthquake, a building might sustain a drift of 1 to 2 percent. The U-M structure easily withstood a drift of 3 percent.
The new beams could provide an easier, cheaper, stronger way to brace buildings in earthquake-prone areas.
The researchers are now working with a structural design firm to install the beams in several high rises soon to be under construction on the west coast.
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This research is funded by the National Science Foundation under the Network for Earthquake Engineering Simulation Program. (3100 )
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6. .
1. We know sandstones to consist of grains of quartz held together by cement or matrix.
2. Mortar is known to be a matrix.
3. Building materials to be used for bearing structures are timber, artificial stone and metals.
4. Cement is supposed to be the most important component of concrete.
5. We suppose high alumina cement to be very resistant to chemical attack.
6. Sandstone is considered to be excellent material for road construction.
7. The scientists consider all metals to be divided into ferrous and non-ferrous metals.
8. The builders decided to use brick for the wall construction.
9. Silica brick to be prepared under great pressure is largely used.
10. We suppose standardized factory-made elements to be widely used.
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1. The regulations now state that no gas can be used in blocks of flats that have more than12 storeys.
2. Ukrainian town-building experience has shown that it is not economical to build comprehensive service centers.
3. Providing the material is homogenous, that is of uniform consistency, the stress is independent of the material used.
4. It is necessary that a means should be provided to protect walls from being penetrated by water.
5. It is necessary to mention that a new polyvinyl plastic has been introduced.
6. A method of construction that speeds up building houses is one using large prefabricated sections.
7. The Iron Age brought tools that led to the development of carpentry.
8. One should know that a good plan is the one that forecasts the future development.
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9. Mortars should be proportioned so that the mix has good plastic quality in its wet state.
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1. I would not build on that if I were you.
2. He is not built that same way.
3. They have built in their garden with the wall just recently.
4. We need more place and I would like to build a wing on to our house.
5. Much work has built up over the past years.
6. Carpenter builds or dismantles wood or metal framework.
7. Bricklayer is a tradesman who builds and repairs brick work.
8. Walls are built to enclose areas and carry the weight of floors and roofs.
9. Modem flat is impossible without built in furniture.
10. This monument was built up by a famous architect.
9. , .
1. Decorative asbestos fabrics are used in the house where the public assembles.
2. The building materials, which are produced at this factory, are widely used on the city construction sites.
3. One of the most important requirements when we use timber is to see that it is properly dried.
4. This property determines the ways in which they are used.
5. What do you do to cut the labour expenses that are connected with the erecting of a house at the construction site?
6. In a space heated by radiators, where there is no fan, the air, which comes into contact with the radiators, is heated and made lighter.
7. The fact that the lime can be slaked was discovered by the Romans.
8. Egyptian pyramids are huge structures that are almost 4,600 years old.
9. The fact that cement is used widely as a binding material is quite reasonable.
10. Nowadays plastics, which are artificial materials, can be applied to almost every branch of building.
10. .
Customer: I would like to order a countryside house. Here is the project.
Foreman: Let`s see. A two-storey house with a garage. Ten rooms and two staircases. What will the foundation be made of? Concrete?
C.: Yes, ferroconcrete.
F.: And what about the walls?
C.: I want red brick walls. The windows are large. By the way, the panes should be airtight. I want them to be double-glazing.
F.: We`ll make them hermetic with putty. We put it in the grooves, and then fix the panes.
C.: Excellent. The hinges and handles should be bronze.
F.: Ok. What type of roof would you like?
C.: I want the roof to be flat, with a small garden.
F.: Do you have an interior-designer?
C.: Yes, but the drafts aren`t ready.
F.: What idea does he have?
C.: There will be a mantelpiece in the hall and the walls will be decorated with panels.
F.: Plastic panels?
C.: Oh, no. Panels must be made of wood.
F.: What wood do you prefer?
C.: I think oak is the best.
F.: How do you pay the construction?
C.: I`ve got mortgage fir 25 years from the bank.
F.: So, we`ll make oak panels then.
