Evaluation of the stiffening of structural components in two-way joist concrete slab floors for vibration control under human walking

Abstract

The stiffening of structural components in waffle slabs systems as remedial measure to control acceleration under human walking is evaluated. The stiffened structural components were: slab, beams, joists, domes at the edges and domes at the centre of the span. The stiffening of the slab was achieved with the increment of modulus of elasticity of concrete and with the increment of the depth of the structural components, using normal or lightweight concrete. The increment of the stiffness of the beams and joists was achieved with the increment of their depths, consequently, the second moment of area was increased. The evaluation of the stiffening of these structural components to control vibration was carried out in finite element models of a two-way joist concrete slab panel. The modelling of the panel was detailed, the concrete slab and solid heads were meshed with shell finite elements, beams, joists and columns with frame finite elements. The numerical models were calibrated and validated with the natural frequency obtained with experimental ambient vibration tests. The concrete slab lies in two-way joists, which are also supported on three principal beams and on a wall at the panel edges. Three principal beams are supported at the corners of the panel on solid heads over square section columns, but one beam is supported on a wall. As a result of the evaluation of the stiffening of structural components in the numerical models of the waffle slab system, the remedial measures to reduce the acceleration induced by human activities are: increment of the concrete modulus of elasticity, increment of the slab thickness, increment of joists depth, increment of only pairs of central joist depth, increment of the depth of structural components of waffle slabs with lightweight concrete, and filling up the domes with normal or light weight concrete which are along the perimeter edges and at the centre of the span. On the contrary, increment of the principal beam’s depth is not a remedial measure to control accelerations.