Integrated parametric modelling and structural design for precast concrete stairs

Abstract

Precast concrete elements such as beams, columns, stairs and shear walls are widely used in building construction. This thesis proposes an integrated parametric model for precast concrete stairs (PCS) which supports design exploration as well as circulation, structural and material performance analysis. First, a process model for PCS design is defined. This model is used to develop requirements for a computational PCS design environment. Expressions and equations regarding structural performance of the staircase are introduced. A parametric model for PCS is described. The model addresses half turn, open-Z PCS which are chosen because they are commonly used in construction practice. A top-down PCS generation process starting with the definition of independent stairwell parameters is adopted. Stair parameters are defined next. Finally, material characteristics and structural parameters such as reinforced concrete specific weight and rebar diameters are specified. Circulation, structural and material quantity performance indicators are specified and would be evaluated automatically as required data become available. A prototype of the parametric model is implemented in the Grasshopper/Rhino parametric modelling environment. This environment has been chosen because it provides considerable support for rapid application development and intuitive user interfaces. A case study is presented which illustrates how the prototype may support integrated PCS design and limitations of the prototype and possible future extensions that address the needs of the PCS industry are discussed.