Concrete Shear Walls Example

Concrete Shear Walls Example Concrete Shear Walls â€" Assignment Example > Concrete Shear WallsHistory of Shear WallsIn various regions and countries around the globe that experience regular earthquakes, buildings with cast-in-situ reinforced shear walls are common. This building technique has been used since late 1950s and early 1960s in urban areas to construct tall buildings. Prior to the introduction of concrete shear walls, masonry structures were designed using empirical procedures based on the past performance of similar structures. Because shear wall technique was not being used, early concrete structures used to be massive so as to effectively withstand vertical as well as lateral loads. Even though this rational or empirical technique is still being employed on a limited basis, earthquakes and strong winds have shown that a more defined and logical technique is required to design concrete structures that can effectively withstand disastrous forces caused by strong winds and earthquakes. In early 1950s, elastic working stress design techniques w ere introduced to be used to design reinforced concrete structures. Using this new elastic design technique, builders started reinforcing concrete structures with steel so that the steel could withstand tensile forces while concrete took care of compressive forces. By mid 1950s, the Uniform Building Coded included working stress design techniques for masonry which allowed builders to size masonry members by making sure that expected service was not above the permitted design stress (Reitherman, 2012). With this working stress design technique, builders were able to design concrete structures throughout much of the 20th century until concrete shear walls were introduced in late 1950s. From then, the building engineering progressed slowly until early 1980s when the issues regarding energy dissipation and seismic performance became paramount. These issues led to the introduction of reinforced concrete shear walls. A dual system of ductile concrete moment framed coupled with confined concrete shear walls was recognized as the best approach to achieving the required strength to withstand seismic forces. This approach worked perfectly with a perimeter moment frame and an interior shear wall core, or the other way through the use of a perimeter ductile wall and an interior ductile moment frame (Reitherman, 2012). In late 1980s and early 1990s, concrete shear walls coupled with yielding shear links were developed after a successful assessment conducted in 1977. This approach became one of the creative researches that are used to build a less expensive shear wall that can dissipate seismic energy effectively (Reitherman, 2012). During the period between 1950 and 1960, plywood walls were recommended as alternates to diagonally braced wall sections. The basis of preference of plywood for this purpose was their capacity to meet certain requirements outlined by the relevant authorities. However, owing to the advancement in technology and emergence of new building techniq ues, other prefabricated alternatives have made is possible to incorporate shear assemblies into narrow walls that fall at either side of the opening. Examples of new alternatives that have replaced plywood in shear walls are steel-backed and sheet steel shear panels that have been proven to offer stronger seismic resistance than the plywood. Benefits of concrete shear wallsThe benefits of concrete shear walls in the structural design of highrise buildings have long been acknowledged. According to Harne (2014), concrete shear walls are very beneficial because they make buildings strong and resistant to seismic forces caused by earthquakes and strong winds. In most of the tall buildings located in regions prone to earthquakes, concrete shear walls serve as the major lateral load-resisting element. This is why Buildings with reinforced concrete shear walls are widespread in many Earthquake-prone countries and regions, such as Canada, Chile, Romania, Turkey, Colombia, and other areas . According to Harne (2014), shear walls are efficient, both in terms of construction cost and of effectiveness in minimizing earthquake damage in structural and non-structural elements like glass windows and building contents. Properly designed and detailed buildings with shear walls have shown very good performance in past earthquakes. Research found in the past 30 years of the record service history of tall building which containing shear wall element, none of them has collapsed during strong winds and earthquakes (Harne, 2014). According to Marzban, Banazadeh, and Azarbakht (2012), shear walls are the main vertical structural elements with a role of resisting both the gravity and lateral loads such as wind load and earthquake load. It provide sufficient strength and stiffness to buildings in the direction of their orientation, which significantly reduces lateral sway of the building and thereby reduces damage to structure and its contents (Marzban, Banazadeh, Azarbakht, 2012). In other words, the shear walls act as cantilevers in withstanding lateral loads because they are usually subjected to axial forces and moments. These shear walls either can be closed section, open sections or planar typically located around elevator and stair cores or located at the ends of the building.