Finite element method Essay Example | Topics and Well Written Essays - 750 words

Finite element method - Essay Example The different results may also be as a result of giving a poor aspect ratio for the plate elements. However, under normal circumstances, no matter the software program used, the approximate results should always be similar. It is clear that when using a single 8-node quadrilateral plate element in Ansys, the maximum bending stress that can be attained in the process is exactly similar to and the same as the beam theory and the maximum deflection is below 5.7% of the theoretical deflection. In Strand 7, the real maximum bending stress for a single 8-node quadrilateral element is 45.5% that is less than the theoretical bending stress while the deflection is 24.4% below the theoretical deflection. When 10 plate elements are used, Ansys and Strand 7 will have to match the theoretical stress and the deflection of the same. The other plate elements; that is the 4-node quadrilateral plate elements, 6-node triangle plate elements, and 3 node triangle plate elements often give the same approximate stresses and deflections when the two different software programs are used. This shows consistency in the results that the software programs give for those measures. When working towards the results for the 4 node quadrilaterals, the two software programs will require an approximate number of about 150 elements in order to match the theoretical values. As for the 6 node triangles, only 16 elements are needed for the two software programs. On the other hand, for 3 node triangles plate elements, the maximum bending stress is below 1% of the theoretical bending stress and the deflection stress and the deflection is 4.7% less than the theoretical deflection even when 2000 are fed to the two software programs. Aspect ratio refers to the ratio of the length of the side that is the shortest to the side that is the longest. The best element shape is a square that has an aspect ratio of 1 and the poorest element shape has an aspect ratio of less than

Seismic action and methods od analysis Dissertation

Seismic action and methods od analysis - Dissertation Example Earthquakes trigger one mode of vibration which is the lowest fundamental mode besides higher modes which take place as a result of tremors. 2.1 Development of Seismic Regulations The Building Seismic Safety Council was put up in 1997 as an affiliate of National Institute of Building Sciences. Its main purpose is to promote safety of the public by providing guidelines to construction, designing, planning, utilization and regulation of buildings. It deals with reduction of risks posed on buildings by earthquakes. The main areas which the Building Seismic Safety Council focuses on are structures, kinds of buildings and related facilities. The Building Seismic Safety Council believes that the level of risks vary and therefore has a versatile approach to seismic safety that considers the risk of each region or community separately. It works together with construction industry, governments, non-governmental organizations and public in general to meet its objectives (Housner, 1990). It adv ocates for earthquake risk reduction measures to be adopted by organizations and institutions. The Building Seismic Safety Council main goals are; to catalyse development of seismic safety, promote use of appropriate seismic voluntary standards, assess implementation of recommendations and find out opportunities for improving regulations on seismic safety. 2.2 Design Seimic Actions Earthquake is a great disaster to lives and economy and there is need for design of buildings and structures which are resistant to seismic actions. The effect of an earthquake can be enormous to the extent that a region may not be able to help itself. Collaboration between architect and engineers in the foundational planning will help bring out an expertise to improve safety. There is lack of structural undertakings to curb seismic hazards in the world. The design of new buildings must be able to significantly counter earthquakes. Most current buildings lack resistance and others even have more vulnerabi lity to earthquakes. 2.2.1 Seismic Zones of Seismicity of Greece Greece experience earthquakes regularly although they are mild and therefore do not cause significant damage. It is an active region with small earthquakes annually. This has made builders in Greece to develop structures that are safe during earthquakes. The neighboring Turkey has less-strict building regulations and small earthquakes normally cause them large damages. Greece faces potential earthquakes from active volcanoes such as Nysiros Volcano. Most of Greece islands also have fault lines align in different directions. Most of Greek earthquakes originate from under seas which shake the surrounding islands. In 1999, the Athens Earthquake affected its outskirts and people killed, others displaced and buildings collapsed. Ancient Greece also faced earthquakes majorly caused by volcanoes (NATO ADVANCED RESEARCH WORKSHOP ON EARTHQUAKE MONITORING AND SEISMIC HAZARD MITIGATION IN BALKAN COUNTRIES & HUSEBYE, 2008). This i ncluded the Eruption of Thira and Earthquake of 365. 2.2.2 Ground Seismic Acceleration Seismic waves move in the ground causing vibration of the crust. This energy causing vibration is continually transmitted anything that is attached to the ground including buildings and structures. The structures are damaged since they resist making sudden change because of their inertial forces. The rate of move of speed of seismic waves on the ground is dependent on some factors. These include; the type