Design of Reinforced Concrete Buildings for Seismic Performance

Practical Deterministic and Probabilistic Approaches

Mark Aschheim, Enrique Hernández-Montes, Dimitrios Vamvatsikos

• Publisher: CRC Press
• Year: 2019
• ISBN:
  9781315354811
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

The costs of inadequate earthquake engineering are huge, especially for reinforced concrete buildings. This book presents the principles of earthquake-resistant structural engineering, and uses the latest tools and techniques to give practical design guidance to address single or multiple seismic performance levels.

It presents an elegant, simple and theoretically coherent design framework. Required strength is determined on the basis of an estimated yield displacement and desired limits of system ductility and drift demands. A simple deterministic approach is presented along with its elaboration into a probabilistic treatment that allows for design to limit annual probabilities of failure. The design method allows the seismic force resisting system to be designed on the basis of elastic analysis results, while nonlinear analysis is used for performance verification. Detailing requirements of ACI 318 and Eurocode 8 are presented. Students will benefit from the coverage of seismology, structural dynamics, reinforced concrete, and capacity design approaches, which allows the book to be used as a foundation text in earthquake engineering.

Appendix 1

Design charts for rectangular and barbell section walls

A1.1 INTRODUCTION

Design charts (Figures A1.1–A1.13) were developed to provide accurate estimates of nominal flexural strength and yield curvature, for materials having actual strengths equal to the nominal values identified. The basis used to derive the charts is described in Section A1.2, while the application of the charts for use with expected material properties is described in Section A1.3.

A1.2 ASSUMPTIONS USED IN DEVELOPING DESIGN CHARTS

Concrete and steel strengths were taken equal to their nominal values (${f^{\prime }}_{\text{c}}=4,5,\text{and}6\text{ksi}$, and f_y = 60 ksi), respectively. Concrete was assumed to have zero tensile capacity; reinforcing steel was modeled as elastic-plastic. Section analyses follow ACI 318 requirements; constitutive relationships, strain compatibility, and equilibrium were satisfied, assuming plane sections remain plane. Nominal flexural strength, M_n, was determined per ACI 318 at an extreme fiber strain of 0.003.

In most of the cases considered, the curvature corresponding to first yield, ${{\varphi }^{\prime }}_{\text{y}}$ was taken equal to the curvature at the instant in the plane sections analysis that the extreme tension reinforcement reached a strain of ε_y (= f_y/E_s). At this curvature the extreme concrete fiber stress was less than ${f^{\prime }}_{\text{c}}$. In some cases with relatively high levels of axial load and/or high reinforcement ratios, the steel would remain elastic while the concrete reached its strength. In these cases, the “yield” curvature was defined as that corresponding to the extreme concrete fiber reaching a stress of ${f^{\prime }}_{\text{c}}$. Thus, the curvature at first yield was defined by the first event to occur: the extreme tensile reinforcement reaching f_y or the extreme concrete fiber reaching ${f^{\prime }}_{\text{c}}$. The corresponding moment was termed the yield moment ${M^{\prime }}_{\text{y}}$.

The effective yield curvature, ϕ_y, for the cross section was determined by extrapolating the first yield value to the point where the moment reaches the nominal strength level:

${{\varphi }^{\prime }}_{\text{y}}=\frac{M_{\text{n}}}{{M^{\prime }}_{\text{y}}}{{\varphi }^{\prime }}_{\text{y}}(A1.1)$

where M_n = moment resistance corresponding to a concrete strain of 0.003 at the extreme compression fiber and ${M^{\prime }}_{\text{y}}$ = moment resistance when longitudinal boundary reinforcement strain reaches ${\epsilon }_{\text{y}}$(or where the extreme concrete fiber reaches ${f^{\prime }}_{\text{c}}$).

The effective yield curvatures plotted below are consistent with the observations of Paulay (2002), who suggested effective yield curvatures of 1.8ε_y/l_w and 2.0ε_y/l_w for rectangular section walls with and without longitudinal boundary (end) reinforcement, respectively. These two values correspond to 0.0037/l_w and 0.0041/l_w, respectively, for Grade 60 reinforcement. Paulay also suggested effective yield curvatures for other cross sections: 2.0ε_y/l_w for I- and C-shaped sections, and 1.4ε_y/l_w for T-shaped sections in which the flange is in compression and 1.8ε_y/l_w for T-shaped sections in which the flange in tension.

The parametric analyses are based on lumping the longitudinal boundary reinforcement A_s = ρ(2dʹt_w) at a distance dʹ from the edge of a rectangular section, and A_s = ρ(t_ft_w) at the ce...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication Page
• Table of Contents
• Acknowledgments
• Authors
• Section I Introduction
• Section II Seismic Demands
• Section III Essential Concepts of Earthquake-Resistant Design
• Section IV Reinforced Concrete Systems
• Section V Design methods and examples
• Appendix 1
• Appendix 2
• Appendix 3
• Index