Author : Manouchehr Hakhamaneshi
Publisher :
ISBN 13 : 9781321608755
Total Pages : pages
Book Rating : 4.6/5 (87 download)
Book Synopsis Rocking Foundations for Building Systems - Effect of Footing Shape, Soil Environment, Embedment and Normalized Moment-to-shear Ratio by : Manouchehr Hakhamaneshi
Download or read book Rocking Foundations for Building Systems - Effect of Footing Shape, Soil Environment, Embedment and Normalized Moment-to-shear Ratio written by Manouchehr Hakhamaneshi and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation investigates the effect of footing shape, soil type, footing embedment and normalized moment-to-shear ratio on the cyclic performance of shallow footings subjected to rocking. The test results were used to validate modeling parameters and acceptance criteria of rocking shallow foundations in the new ASCE 41-13 standard. The results presented in this study are based on three series of large-scale centrifuge tests and thirty two small-scale centrifuge tests. The large tests included slow cyclic and dynamic shaking loading, but the small centrifuge tests only applied slow cyclic loading to the footings. Previous centrifuge test results have well characterized the behavior of rectangular rocking footings on sand, but few results are available for clayey ground. Gajan et al. (2005) and Deng et al. (2012) have shown that moment capacity of a rocking footing on sand can be accurately predicted using conventional equations. Tests on clay reported herein verify that the same equations hold for moment capacity of rectangular footings on clayey ground. The results reveal that for similar critical contact area ratio (ρac) and rotation demand, footings on clay settle about 20 to 40% less than those on sand. The standard ASCE 41-13 Seismic Evaluation and Retrofit of Existing Buildings includes new provisions for linear and non-linear modeling parameters and acceptance criteria for rocking shallow foundations. The new modeling parameters and acceptance criteria were largely based on model tests on rectangular rocking footings with a limited range of footing length to width ratio (L/B). New model test results are presented, including a systematic variation of L/B and also non-rectangular (H-shaped, C-shaped, and trapezoidal) footings. A tri-linear backbone curve is introduced to model the hysteretic moment-rotation behavior of rectangular and H-Shaped footings. The standard provides equations for rotational stiffness, K50, based on elasticity theory (Gazetas 1991). A simpler empirical method for obtaining the initial stiffness, K50 = 300M(c-foot), is proposed for rectangular footings, where M(c-foot) is the moment capacity of the footing. For H-shaped footings, it is found that K50 varies from 400M(c-foot) to 700M(c-foot). The new ASCE 41-13 provisions are limited to cases with M/VL > 1, which is considered to be a criteria that will ensure that the footing is rocking dominated (i.e., rocking deformations are more significant than sliding deformations). It is shown in this thesis that footings with 0.7M/VL
