DYNAMIC ANALYSIS OF PRESTRESSED CONCRETE BEAMS WITH OPENINGS

There is a growing trend in constructing multistory garages and high-r ise buildings where utility ducts are passed through openings in the f loor beams. Accommodating the utility services in such a manner minimi zes dead space. However, introducing an opening in the web of such bea ms reduces the beam stiffness and leads to a more complicated structur al response. In this paper the dynamic analysis and design of simply s upported and continuous prestressed concrete beams with rectangular op enings are presented. Several design parameters are varied such as ope ning width and depth, horizontal and vertical locations of the opening , type of cross section, and presence of more than one opening. The an alytical results were compared to test results in the literature. Good agreement was shown between the theoretical and the experimental resu lts. An extensive parametric study was performed on prestressed beams with openings to determine the natural frequencies and the associated mode shapes. Simple methods are proposed to predict the dynamic respon se including the beam maximum deflection, deflection of the opening ch ords, and horizontal and vertical stresses at midspan and at the vicin ity of the opening.