<title>Auto-adaptive response modification in moment-resisting frame structures</title>

Abstract

The response of the simplified moment resisting frame structure discussed in this paper is characterized by relatively large elastic deflection capacity with reduced residual deflections, auto-adaptive system stiffness modification, and considerable energy dissipation. The suggested structural system is assembled from particular column and beam elements with elastic and elastic/plastic load-deformation characteristics utilizing advanced composite materials and common construction technology without use of mechanical devices. Conventional frame structures, exclusively utilizing steel reinforced concrete members, ultimately form a collapse mechanism upon formation of plastic hinges in the beam and column members. While the flexural strength of the columns in the proposed system exceeds that of the beam as required in seismic design provisions, the relative stiffness of the frame members changes upon formation of plastic hinges in the beam element. This switching mechanism and the resulting modification of frame stiffness are inherent structural properties of the system, which can be adjusted to specific requirements in the design process. Although extensive inelastic rotation occurs in the beam element, plastic hinges at the column base are not required in order to initiate and utilize the energy dissipation potential of the beam element. In this frame configuration, the auto-adaptive stiffness modification is expected to reduce structural demand in terms of base shear forces under dynamic excitations while the formation of a kinemetic mechanism is prevented.