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New Methods and Materials

Use of new materials in developing Countries

A major problem in developing countries is poor construction.  Concrete is primary building material since it is made from common materials from the ground.  However, developing countries rarely use timber or steel.  Steel is often too expensive since it is made in developed countries and shipped where needed.  Also, wood is usually not available because of few forests and it is expensive to ship.  Therefore, the primary building materials are concrete or clay.  Concrete is used in masonry blocks or in cast beams and columns.  Clay is made into bricks.

The problem with concrete and brick is that they are not effective at resisting forces in earthquakes that cause tension and shear.   These forces cause cracking and failure.  Since concrete is heavy, that makes seismic loads worse when earthquakes shake heavy buildings.  Therefore, a building that may stand up day to day could fall in earthquakes.

Two problems need to be solved:  First, what should be done with buildings already built using poor construction?  Second, how can new construction be made that will resist earthquakes but not cost too much money?

Retrofit of existing buildings

What can be done to make building durable?  The same problem can exist with older buildings in the US.  In developed countries, one solution is to glue on carbon fibers that are also used in lightweight airplane wings.  This is much too expensive to consider doing in developing countries.  If they could not afford the steel bars in the construction originally, they can’t afford high-grade airplane parts.geotextile on wall

Mohammad Mansourikia and Dr. Hoback have worked on using less expensive materials.  For example, geotextile is a fabric that is used in other civil engineering applications.  The fabric can be glued onto the sides of buildings in X patterns to add strength.  It is much cheaper than carbon fibers.

Read more:  Retrofit of Unreinforced Masonry Walls Using Geotextile and CFRP, M.T. Mansourikia & A. Hoback, Electronic Journal of Structural Engineering, Issue 8 of Volume 14, 2014.

Constructing new buildings

Steel bars in concrete buildings are the most common method to carry shear and tension forces caused by earthquakes.  Dr. Hoback and a few students are looking at inexpensive building materials that can be used instead of steel bars.

One possible material is bamboo.  Bamboo is a grass that grows across the world.  It is stronger than most wood.  It has high tension strength, but not as high as steel.  Since it grows very quickly, it doesn’t take much forest space to grow it.

There are a few problems with bamboo that need to be resolved.  First, when put into concrete, it absorbs the water and swells, then later it dries it contracts.  This makes it hard to connect with concrete which doesn’t swell.  Our sister university, Santa Clara U is working on this problem.

Second, most engineers have no experience with bamboo.  Therefore, Detroit Mercy is working on evaluating different uses of bamboo in parts of concrete structures.  Also, Detroit Mercy is working on new ways of connecting the bamboo to the concrete.

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