The “Building Code Requirements for Structural Concrete” (“Code”) covers the materials, design, and construction of structural concrete used in buildings and where applicable in nonbuilding structures. The Code also covers the strength evaluation of existing concrete structures. Among the subjects covered are: contract documents; inspection; materials; durability requirements; concrete quality, mixing, and placing; formwork; embedded pipes; construction joints; reinforcement details; analysis and design; strength and serviceability; flexural and axial loads; shear and torsion; development and splices of reinforcement; slab systems; walls; footings; precast concrete; composite flexural members; prestressed concrete; shells and folded plate members; strength evaluation of existing structures; provisions for seismic design; structural plain concrete; strut-and-tie modeling in Appendix A; alternative design provisions in Appendix B; alternative load and strength reduction factors in Appendix C; and anchoring to concrete in Appendix D. The quality and testing of materials used in construction are covered by reference to the appropriate ASTM standard specifications. Welding of reinforcement is covered by reference to the appropriate American Welding Society (AWS) standard. Uses of the Code include adoption by reference in general building codes, and earlier editions have been widely used in this manner. The Code is written in a format that allows such reference without change to its language. Therefore, background details or suggestions for carrying out the requirements or intent of the Code portion cannot be included. The Commentary is provided for this purpose. Some of the considerations of the committee in developing the Code portion are discussed within the Commentary, with emphasis given to the explanation of new or revised provisions. Much of the research data referenced in preparing the Code is cited for the user desiring to study individual questions in greater detail. Other documents that provide suggestions for carrying out the requirements of the Code are also cited.

"building code requirements for structural concrete (aci 318-11) and commentary"

Developed herein is an improved pushover analysis procedure based on structural dynamics theory, which retains the conceptual simplicity and computational attractiveness of current procedures with invariant force distribution. In this modal pushover analysis (MPA), the seismic demand due to individual terms in the modal expansion of the effective earthquake forces is determined by a pushover analysis using the inertia force distribution for each mode. Combining these ‘modal’ demands due to the first two or three terms of the expansion provides an estimate of the total seismic demand on inelastic systems. When applied to elastic systems, the MPA procedure is shown to be equivalent to standard response spectrum analysis (RSA). When the peak inelastic response of a 9-storey steel building determined by the approximate MPA procedure is compared with rigorous non-linear response history analysis, it is demonstrated that MPA estimates the response of buildings responding well into the inelastic range to a similar degree of accuracy as RSA in estimating peak response of elastic systems. Thus, the MPA procedure is accurate enough for practical application in building evaluation and design. Copyright © 2001 John Wiley & Sons, Ltd.

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A modal pushover analysis procedure for estimating seismic demands for buildings

A relatively simple nonlinear method for the seismic analysis of structures (the N2 method) is presented. It combines the pushover analysis of a multi‐degree‐of‐freedom (MDOF) model with the response spectrum analysis of an equivalent single‐degree‐of‐freedom (SDOF) system. The method is formulated in the acceleration‐displacement format, which enables the visual interpretation of the procedure and of the relations between the basic quantities controlling the seismic response. Inelastic spectra, rather than elastic spectra with equivalent damping and period, are applied. This feature represents the major difference with respect to the capacity spectrum method. Moreover, demand quantities can be obtained without iteration. Generally, the results of the N2 method are reasonably accurate, provided that the structure oscillates predominantly in the first mode. Some additional limitations apply. In the paper, the method is described and discussed, and it basic derivations are given. The similarities a...

A Nonlinear Analysis Method for Performance‐Based Seismic Design

Pros and cons of a pushover analysis of seismic performance evaluation

PART 1 DEALS WITH THE DYNAMIC ASPECTS OF THE SUBJECT: MATHEMATICAL ANALYSIS OF SYSTEMS SUBJECTED TO INDEPENDENT VIBRATIONS BY MEANS OF MATHEMATICAL MODELS. THE ANALYTICAL SYSTEMS USED ARE NON-LINEAR SYSTEMS, HYDRODYNAMICS AND NUMERICAL METHODS. PART 2 EXAMINES SEISMIC MOVEMENTS, THE DYNAMIC BEHAVIOUR OF STRUCTURES AND THE BASIC CONCEPTS OF THE SEISMIC DESIGN OF STRUCTURES.

Fundamentals of earthquake engineering

A method is proposed to determine design forces for earthquake-resistant design of reinforced concrete structures. The method uses a modified linear model of the structure and recognizes the effect of energy dissipation in the nonlinear range of response. Thus, the designer is provided with a procedure, at the level of linear spectral response analysis, with explicit options about the levels of inelastic response in different elements of a multistory reinforced concrete structure. The paper contains analytical tests of two-story to 10-story frames designed according to the proposed method.

Substitute-structure method for seismic design in r/c

Inelastic Responses of Reinforced ConcreteStructure to Earthquake Motions

A simple analytical model is developed for the calculation of the seismic displacement history response of reinforced concrete frame and frame-wall structures. The computer cost for the model is approximately three precent of that for a MDOF system. A structure is idealized as a single-degree system consisting of a mass mounted on a rigid bar connected to the ground by a hinge and a nonlinear rotational spring. The primary force-deformation relationship for the spring is obtained by a static analysis of the multistory structure. To account for stiffness changes during an earthquake, a simple hysteresis model comprising only four rules is developed. The model is examined for eight small-scale ten-story reinforced concrete test structures, and the analytical results are compared with the measured response histories. The model is shown to be successful in most instances.

Simple nonlinear seismic analysis of r/c structures

This paper presents a simplified method of ranking reinforced concrete, low-rise, monolithic buildings according to their vulnerability to seismic damage. The ranking process requires only the dimensions of the structure. The process is tested using a group of buildings that suffered various level of damage during the Erzincan earthquake of 1992. The ranking procedure reflected the observed damage satisfactorily. - buildings; earthquake resistant structures; earthquakes; evaluation; failure; inspection; reinforced concrete; school buildings.

Seismic Vulnerability Assessment of Low-Rise Buildings in Regions with Infrequent Earthquakes

Two basic characteristics of reinforced concrete structures play an important role in determining response to strong ground motions. They are the changes in stiffness and energy dissipation capacity. Both can be related to the maximum displacement. Results of dynamic tests of reinforced concrete frames are used to illustrate the effects on dynamic response of changes in stiffness and energy dissipation capacity. It is shown that maximum inelastic response can be interpreted in terms of linearly elastic analysis by reference to a fictitious linear structure whose stiffness and damping characteristics are determined as a function of the assumed or known maximum displacement. This leads to a simplified method for estimating the design base shear taking account of inelastic response. The object of this paper is to describe basic phenomena of energy dissipation in reinforced concrete structures subjected to strong ground motion, and to present a simplified method for estimating the design base shear corresponding to inelastic response.

Mete A. Sozen

Papers

Substitute-structure method for seismic design in r/c

Inelastic Responses of Reinforced ConcreteStructure to Earthquake Motions

Simple nonlinear seismic analysis of r/c structures

Seismic Vulnerability Assessment of Low-Rise Buildings in Regions with Infrequent Earthquakes

Inelastic responses of reinforced concrete structures to earthquake motions