Limit Design for Direct Control on Serviceability

Abstract

Any theory of design for reinforced concrete structures implies a minimum structural cost for which all failure modes, or limit states, are covered in the design for specified loading and geometric configuration of the structure. The critical limit states are safeguarded by adequate performance at ultimate and service design load levels through adopting a certain philosophy of design. The present paper proposes a limit‐state design method based on a design philosophy whereby direct design control is exercised on the service behavior of the structure by prespecifying the yield‐moment and rotation capacities of each of the critical sections of the structure. Both strength and deformability criteria are simultaneously satisfied in the design at the specified service and ultimate load levels. An optimal limit design formulation for the design problems is obtained. Suitable algorithms and related computer codes are used to solve the design problem having a nonlinear cost function and explicit nonlinear constraints. An example continuous beam is completely designed by the proposed method. A practical‐sized building frame example is also presented to demonstrate an application of the method to moderately complex framed structures.