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Effect of glass fibre on reinforced concrete beams with metakaoline subjected to cyclic loading. Illustrate your essay with specific examples.

In search of habitat humans have explored even remotest of places on earth due to sudden and rapid expansion of human civilizations. In this process of progressive expansion, man has made cutting edge advancement in technologies of construction and has mastered the art to counter nature's wrath over the years, by learning from his mistakes. The major contributing sources to this space crunch have been globalization, high productivity and growth leading to expansion of civilization and high rise in population. This has also led to building of structures in seismic prone zones and hence it necessitated a set design strategy for developing safe building structures. It has been quite popular belief to construct building structures which are able to survive strongest of earthquakes. But the construction of these structures is not only difficult but is also not considered as a viable economic option. In practicality structures are build on the philosophy that they can withstand moderate ground motions without undergoing any kind of physical damage or under occasional moderate ground shaking they can not only prevent structural damage but also minimize any kind of non-structural damage. It must also be kept in mind that the structure should be able to avoid collapse or serious damage in case of rare major ground shaking.

Inertia forces are generated in form of seismic waves traveling in all directions resulting from ground movements these are also called Earthquake loads. These waves in turn create certain 'demands' or test the structures in terms of their strength, ductility and energy. Their magnitude is highly variable which depends on the seismic activity in the area and the dynamic characteristics of the building. The basic design principle, which any earthquake-resistant structure must satisfy in order that it does not collapse, is that the "Seismic demand" should be greater than the "Computed capacity". Where, 'Seismic demand' is defined as the measure of effect on the structure due to dynamic loads generated by ground movement. The amount of resistance that a structure can offer without failure is called as 'Computed capacity'. For design purposes 'Design Demand' is computed which is the maximum value of seismic demand. In order to balance between cost and safety, it becomes a tough decision for the designer to choose an appropriate design. (Rai, 2000) Many factors such as geographical conditions, availability of raw materials and labor, equipments, political considerations, total cost etc becomes a major factor in consideration.

From the days of usage of ordinary Portland cement for construction we have come a long way in the techniques of construction. Now fabrication with admixtures and fiber reinforcements has paved the way for high strength composite concretes which have enhanced durability and workability than ordinary cement. It has been found that the glass fiber used in concrete degrade due to alkali conditions in the concrete. To counter the alkali effect metakaoline admixture was proved to be useful. It reacts with the free lime produced and thus there is very little free lime available to form crystals. But the total cost of composite concrete increases. It was found that glass fiber reinforced concrete mixed with metakaoline admixture is able to retain its flexural strength and properties even undergoing dynamic changes. The high cost of fiber metakaoline composite necessitates the development of low cost high strength composites.

With the advent of computers and engineering capabilities analyses is becoming increasingly easy but problems are now becoming more complex and ground motions more severe posing challenge to scientific community to invent better techniques and materials of construction so that in future dangers of earthquake can be mitigated. There is lot of research left to be done on properties of metakaoline and a need to develop better cyclic loading models which can imitate real life conditions. Today we face with a serious challenge to undertake counter measures to control the unpredictable hazard to life and property.

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