Comparative Analysis of Stresses in a Building Frame

The increase in the price of land in the cities has made it necessary to build high buildings in order to get a large commercial space on a small parcel of land. The type of building generally used is known as the steel skeleton building. In this type of building the live and dead loads, including the weight of the walls, are carried by a system of beams and girders to columns and are carried by the columns to the footings. In high buildings, the horizontal shear due to the wind load is very large; and since it is impracticable to put diagonal braces between the columns, it is customary to make the building frame rigid enough to resist the horizontal shear by virtue of the stiffness of the columns and girders. With the increased use of reinforced concrete and the adoption of welding, the tall building frame, with moment-resisting connections, forms a very rigid frame. The rigid-frame wind bent is a highly indeterminate structure that can only be analyzed correctly by the methods of indeterminate structures. Nevertheless, it is common practice to analyze such frames by simple approximate methods. The purpose of this study is to take a building frame, in the ten to twenty story range, and determine the amount of time required to calculate the stresses due to wind loads using several different methods; also to determine the variation in the stresses by these different methods. From these results, conclusions can be drawn as to whether there is enough variation in the stresses between the approximate and more exact methods to warrant spending the additional time that the more exact methods require