Title: Sparse Grid Modeling of Carbon Fiber-Reinforced Polymer- Strengthened Pilotis under Biaxial Load

Author(s): Yail J. Kim, David Micnhimer, and Hong-Gun Park

Publication: Structural Journal

Volume: 118

Issue: 6

Appears on pages(s): 19-32

Keywords: biaxial loading; carbon fiber-reinforced polymer (CFRP); column; retrofit; sparse grids; strengthening

DOI: 10.14359/51728190

Date: 11/1/2021

Abstract:
This paper presents analytical investigations into the performance of a piloti taken from a soft story building that is subjected to biaxial loading as a result of a recent earthquake in Pohang, South Korea. The behavior of the piloti is comparatively studied with and without carbon fiber-reinforced polymer (CFRP) confinement using a stochastic process: sparse grids built upon polynomial chaos expansions (PCEs). The Bresler and the Parme methods are implemented in conjunction with the provisions of published design guidelines. CFRP confinement improves the axial and shear capacities of the column, while the biaxial resistance predicted by the Bresler and the Parme methods varies with the magnitude of eccentricity, particularly for the compression-controlled region. The failure envelopes developed per the Bresler method are larger than those based on the Parme method, accompanied by an abrupt discontinuity when the column’s failure alters from the compression- to tension-controlled modes at the balanced eccentricity. According to a parametric study with variable geometric and material properties, the aspect ratio and concrete strength of the confined column dominate the biaxial capacity; however, the influence of the steel-reinforcement ratio and CFRP modulus is minimal. Design recommendations are proposed for CFRP-confined columns under biaxial loading and assessed against experimental data collected from literature.