Kadir Guler

Estimation of the Fundamental Vibration Period of Existing RC Buildings in Turkey Utilizing Ambient Vibration Records

Earthquake design codes generally provide empirical formulae or various approximations for determining fundamental periods of buildings for the evaluation of statically equivalent seismic forces. It is thus important to use realistic periods for the design and performance assessment of existing buildings. This study deals with the evaluation of fundamental vibration periods of reinforced concrete (RC) buildings having a frame-type structural system, and considers the effects of infill walls. The problem is evaluated by utilizing experimental and analytical approaches. A height-dependent relationship to estimate the fundamental period of vibration of Turkish RC moment-resisting frames is derived for a fully elastic condition. Furthermore, a constant parameter is defined to magnify the empirical relationship in order to attain code-specified periods obtained by considering moderate-intensity earthquakes.

LOCALIZATION AND SIZE-DEPENDENT RESPONSE OF REINFORCED CONCRETE BEAMS

This paper describes an experimental investigation conducted to determine whether the flexural response of reinforced concrete beams is size (length) dependent. 16 normal- and high-strength concrete beams were tested with 4 different constant-moment zone lengths and 2 different reinforcement ratios. Closed-loop control was used to obtain post-peak behavior, which allowed additional information about the failure mechanisms to be obtained. Results indicate that damage localization occurs in the compression zone, and the size of the damage zone is constant between specimens of different size. Evidence of strain-softening behavior could be seen by comparing local and global strains. While moment-carrying capacity of different size beams was relatively constant, the average strain at yield and maximum moment was observed to be slightly dependent on specimen length. The overall ductility of the beams was dependent on the constant-moment zone length, with larger specimens demonstrating a more brittle response.

Dynamic response of a column with foundation uplift

Abstract The effects of transient foundation uplift on the dynamic response of a column with attached masses supported on a Winkler foundation are investigated. The analysis developed here is based on the assumption that the column, having continuously distributed mass and rigidity, is supported on a tensionless elastic foundation through a rigid circular base plate. The method employed includes use of series expansion of the lateral displacement of the column, application of the Galerkin technique and step-wise solution of the governing equations of the problem. Besides the free vibrations of the column, the forced vibrations of the system are investigated for an assumed harmonic ground motion excitation. Additionally, the dynamic response of the system to the El Centro 1940 ground motion is presented.

DYNAMIC RESPONSE OF A RECTANGULAR PLATE-COLUMN SYSTEM ON A TENSIONLESS ELASTIC FOUNDATION

Response of a plate-column system having five-degree-of-freedom supported by an elastic foundation and subjected to static lateral load and earthquake motion is studied. Two Winkler foundation models are assumed: a conventional and a tensionless model. The governing equations of the problem are obtained, solved numerically and the results are presented in figures to demonstrate the behaviour of the system comparatively for the two types of Winkler foundation models.