Interstory drift based scaling of earthquake ground motions

A novel amplitude scaling procedure is proposed in this study where the ground motion scaling factors are defined as the ratio of interstory drift distributions under target spectrum versus under the associated ground motion spectrum. The advantage of employing interstory drift ratio in ground motion scaling, compared to employing spectral intensity directly, is that it provides a strong theoretical link between the target spectrum intensity and the fundamental dynamic characteristics of the structure. Hence, scaling is conditioned on structural response, which is in turn a function of seismic intensity. The interstory drift-based scaling procedure (IDS) is presented herein for planar frames for brevity. Accuracy and efficiency of the IDS procedure is assessed under a set of near fault strong motions from large magnitude events. The results revealed that the proposed procedure is accurate since the resulting bias in estimating linear elastic interstory drifts is negligibly small. Further, it is noticeably more effective as compared to the conventional procedures suggested in recent seismic codes, yet it is simpler

A LINEAR MATHEMATICAL-MODEL FOR THE SEISMIC INPLANE BEHAVIOR OF BRICK MASONRY WALLS .2. DETERMINATION OF MODEL PARAMETERS THROUGH OPTIMIZATION USING EXPERIMENTAL-DATA

WOS: A1984SV07000003

Correlation relation between professional qualifications of physical education teachers and students’ attitudes towards Physical Education classes

Purpose: This empirical study investigated the impact of the professional qualifications of Physical Education (PE) teachers on secondary school students’ attitudes towards their PE classes. Education in general and teaching and learning in particular are multidimensional phenomena and thus it is essential to determine and define these dimensions to sustain quality in education. From the psychological perspective, along with various factors, teachers’ personality and qualifications may affect students’ learning process. In this respect, effective teachers can foster students’ learning process and help develop positive attitudes towards a course. Material: In order to fulfill the research aim, the data were elicited through a questionnaire from five hundred and ninety-two secondary school students from grades 9, 10 and 11in North Cyprus to be analyzed quantitatively. Kolmogorov-Smirnov Test and Shapiro-Wilk Testwere run to test normality. Seeing that the data set was not well-modeled by a normal distribution, a Spearman's rank correlation coefficient was run to measure the association between the variables. Results: A very strong positive correlation was found between the professional qualifications of teachers and the participants’ attitudes towards PE classes. Conclusions: The results indicated that there was a significant relationship between the qualifications of the teachers and the students’ attitudes towards PE classes. More specifically, it was found that the higher the perceptions of students of the professional qualifications of PE teachers, the more positive attitudes they developed towards PE classes

A linear mathematical model for the seismic inplane behaviour of brick masonry walls part 1: Theoretical considerations

In this study two mathematical models are presented for the linear dynamic behaviour of masonry walls. The study is completed in three stages: experimental observations, selection of a mathematical model and the determination of model parameters through optimization analysis. In the present paper (Part 1) the theoretical analysis used in the development of the mathematical models is presented. Part 2 is devoted to the optimization analysis. Evaluation of the experimental data, which is described in detail in Part 2, indicates that the first two modal frequencies of the wall specimen are close to each other. This may be attributed, on physical grounds, to strong interaction between the brick and mortar phases of the wall. Accordingly, a two-phase mathematical model, namely a mixture model (MM), is chosen to describe the wall behaviour because it can differentiate between the two phases of the wall and take into account the interaction between them. The equations of MM are put into a discrete form to simplify the optimization analysis. As a special case, MM contains a simple one-phase model called the effective modulus model (EMM). The equations of EMM are also established. Finally, the theoretical complex frequency response functions (CFRF) predicted by MM and EMM are obtained. CFRF relates the top acceleration of the wall to its base acceleration and is the response quantity chosen to be matched in the optimization analysis. Copyright © 1984 John Wiley & Sons, Lt

A linear mathematical model for the seismic inplane behaviour of brick masonry walls part 2: Determination of model parameters through optimization using experimental data

The parameters appearing in the mixture and effective modulus models proposed in Part 1 are determined through optimization by matching theoretical and experimental responses. The optimization analysis is performed in frequency space. The response quantities chosen to be matched are the complex frequency response functions (experimental and theoretical) relating the Fourier transforms of top and base accelerations of the wall. Computations in optimization analysis are carried out by introducing an object (error) function and minimizing it using the Gauss-Newton method. The results show that the mixture model is capable of predicting accurately the dynamic response of masonry walls up to a frequency which is well above the second modal frequency, whereas the effective modulus model describes the wall behaviour only up to the first modal frequency. Furthermore, it is shown that the mixture model is still valid when micro cracks, which may exist between the mortar and brick constituents, are present. Copyright © 1984 John Wiley & Sons, Lt

Interstory drift based scaling of bi-directional ground motions

The interstory drift-based scaling procedure (IDS) developed recently by the authors for plane frames under single component horizontal ground motions, has been extended to three-dimensional structures possessing torsional coupling under bi-axial ground motions which are represented by their geometric mean spectrum. The ground motion-scaling factor is defined as the ratio of average interstory drift along building height under target spectrum versus that under the associated ground motion spectrum. Hence, scaling is conditioned on structural response, which is in turn a function of seismic intensity. IDS for 3D systems is applied to 20-story and 3-story concrete space frames with mass and stiffness eccentricity, respectively. Accuracy and efficiency of the IDS procedure is assessed under a set of near-fault strong motion pairs from large magnitude events. The results revealed that the proposed procedure is accurate and noticeably more efficient as compared to conventional procedures suggested in seismic codes and in literature. Further, the intensity measure employed in the IDS procedure is proved as a good predictor of fundamental demand measures (maximum interstory drift ratio and maximum plastic rotations) obtained from nonlinear dynamic analyses under individual ground motion pairs. Hence, employing the intensity measure of IDS for ground motion scaling in intensity-based evaluation of structures is proposed for reliable estimation of structural performance under code-prescribed seismic hazard

A LINEAR MATHEMATICAL-MODEL FOR THE SEISMIC INPLANE BEHAVIOR OF BRICK MASONRY WALLS .1. THEORETICAL CONSIDERATIONS

WOS: A1984SV07000002