Physical and geometrical non-linear behavior of precast beams on elastomeric supports

Abstract

ResumoThe stability of long and slender precast beams has been associated with structural collapse during the transitory phase of construction. The inevitable deviations regarding the execution between the support cross-section and midspan aggravate the instability problem, thus causing the beams to become even more susceptible to its effects. The focal point of this study is the numerical and behavioral evaluation of concrete beams that present geometric imperfections on elastomeric supports and analyze the influence exerted by the variables of: strength characteristics of concrete, physical non-linearity of the concrete and the compression stiffness of the bearing pad. The numerical analyses were developed on a computer program based on the finite element method (FEM). Among the principle conclusions drawn from the study, one finds that the increase in the characteristic strength of the concrete provides the beam with a higher degree of stability, and the consideration of the physical non-linear behavior of the material did not allow the equilibrium point on the numerical model to be found in some of the cases that were evaluated. The rotational stiffness of the pad decreases as the skew angle increases. Therefore, one needs to remember that in very critical situations, it may not be possible to find the point of equilibrium, thus leading to collapse.

Enlarged brick blocks as an alternative to masonry

“…When using the face tier method, the blocks are made directly at the erected building or at the factory sites using tools, equipment and devices used for ordinary piece bricklaying [9]. Here, as well as during the construction of walls made of separate bricks, the process is divided into separate operations entrusted to masons of various qualifications, but due to the unification of products, the stationarity of workplaces, the absence of the need for supply and placement of materials on the scaffolds, their labour productivity is much higher.…”

Numerical analysis of the effective stiffness of elastomeric bearing pads under precast beams for the limit load of lateral instability

“…Despite the high risk to worker safety and losses caused by this type of collapse, there in fact exist few experimental studies developed on the subject (CONSOLAZIO; HAMILTON; BEERY [3],HURFF; KAHN [4]). Consequently, few numerical studies have been performed to represent the behavior of long beams under rollover failure, when only supported on neoprene bearing pads (KRAHL; CARRAZEDO; EL DEBS [5]; LEE [6]; CARDOSO; LIMA [7]). However, this field of research requires greater investigation in the field of experiment, as well as numerical, in order that recommendations can be established.…”

Wind load effect on the lateral instability of precast beams on elastomeric bearing supports

“…In Bairán and Cladera [4], the elastomeric support device does not offer sufficient stiffness in terms of the toppling of the beam due to the incorrect design of the pad, or that the pad was correctly designed, but positioned in an incorrect manner. The researchers Burgoyne and Stratford [5] along with Plaut and Moen [6], and Cardoso and Lima [7] deal with the lateral instability of beams from precast concrete on deformable supports. The authors show that the stiffness of the support significantly influences the equilibrium and stability of the beam, mainly when faced with wind loads.…”