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    A Method for Determination of Moment Contribution Ratio under Foundation Rotation in Shear Wall-Frame Systems
    (Mdpi, 2024) Bozdogan, Kanat Burak; Keskin, Erdinc
    In shear wall-frame systems, the foundation rotation that may occur under the shear walls changes the displacements and interstory drift ratios and changes the internal force distribution. This study investigates the effect of foundation rotations under shear walls on internal force distribution in shear-frame systems. The originality of the study lies in considering parabolic loads and dynamic analysis (first mode), in addition to static uniform or triangular distributed loads, when determining the shear wall moment contribution ratio under the influence of foundation rotation. The shear wall contribution ratio, a key parameter in many earthquake codes, is defined as the ratio of the sum of bending moments taken by the shear walls at the base to the overturning moment. It plays a crucial role in determining the building's behavior. Depending on this ratio, the load-reduction coefficient is changed. This study investigates the effect of foundation rotation on the moment distribution at the base for three different static load cases and the first mode in the dynamic analysis. The multi-story building is modeled as an equivalent sandwich beam. The moment contribution ratio (MCR) was calculated with the help of analytical solutions of the differential equations written for three different load cases in static conditions, and graphs were created for practical use directly calculating the MCR. In the methodology of the study, the initial step involves the calculation of the equivalent sandwich beam stiffness parameters and the foundational rotational spring. Subsequent to these calculations, the MCR values can be directly obtained with the help of graphs. This approach facilitates the rapid and practical determination of the MCR and can be used in the preliminary sizing phase to eliminate possible errors in the data entry of software that performs detailed analysis. In addition, in the presented study, it has been shown that taking a single mode into account is sufficient when calculating MCR values in dynamic analysis.
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    Öğe
    A Method for Determining the Fundamental Site Period and the Average Shear Wave Velocity
    (World Scientific Publ Co Pte Ltd, 2024) Bozdogan, Kanat Burak; Keskin, Erdinc
    The soil-structure interaction plays a crucial role in determining the displacement and internal forces of multi-story buildings subjected to strong ground motion. One of the critical dynamic characteristics influencing soil-structure interaction is the fundamental site period and the average shear wave velocity associated with it. This study introduces an original equation to determine these parameters. In addition, for the first time in the literature, the version of the Rayleigh method used for finding the fundamental periods of buildings is used to find the fundamental site period. The soil is modeled as an equivalent shear beam to obtain the proposed equation. The peak displacement is obtained by acting the soil mass as an external load on the equivalent shear beam. For single-layer soil, the fundamental site period is proportional to the square root of the peak displacement of the equivalent shear beam. The least squares method generalizes the proposed relation for single-layer soils to multi-layer soil profiles. Modified Finite element Transfer matrix method is used for calibration in the least squares method. The equations used in the literature and earthquake codes for determining the fundamental site period and average shear velocity are tested on various examples, and it is shown that the method proposed in this study, along with the Rayleigh method, gives better results than these equations. The performances of these two methods and the five commonly used equations are tested and compared on different soil profiles. Transfer functions, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are used for verification. For all soil profiles, the results obtained from the transfer function, Finite Element Method (SAP200) and Modified Finite Element Transfer Matrix Method are found to be in agreement. The true percent relative error found in the results obtained with the proposed method is 4.47%.
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    Öğe
    A Practical Method for Determining Dynamic Characteristics of Buildings Under the Effect of Foundation Rotations
    (World Scientific Publ Co Pte Ltd, 2024) Bozdogan, Kanat Burak; Keskin, Erdinc; Ozturk, Duygu
    In multi-storey buildings, unforeseen foundation rotations can change the building's behavior. Therefore, these effects should be taken into account in the analysis. In the studies conducted in the literature, the impact of the rotation of the foundation on the building behavior under static loads has been investigated. In this study, an approach is proposed to determine the dynamic behavior of buildings under the effect of foundation rotation, regardless of the type of bearing system. The multi-storey building was modeled as an equivalent flexural-shear beam in the study. In the study, the axial displacements of the columns, which are neglected in the flexural-shear beam model, are also considered, which is different from the literature. The equation of motion representing the dynamic analysis of the equivalent flexural-shear beam was solved with the help of the Differential Transform Method. The period coefficients, effective mass ratio and peak displacement coefficient for five cases were determined and plotted. A code was prepared using Matlab for the analysis with the Differential Transform Method. As a result of the study, the dynamic characteristics obtained depending on the dimensionless building behavior coefficient have been graphed. Using the given graphs, the dynamic characteristics of the buildings under the effect of foundation rotation can be determined quickly and practically. The method presented in this study can be used for Response spectrum analysis of all systems with pure shear beam, pure bending beam and bending-shear beam behavior. In addition, an approach has been proposed to consider P - Delta effects within the scope of the study. The results obtained in the study were interpreted, and the impact of rotation on dynamic characteristics was discussed. At the end of the study, for the convenience of the presented method, two examples, one for wall-frame and the other for frame systems, were solved with the proposed method, and the results were compared with the SAP2000 program.
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    Öğe
    Free Vibration Analysis of Frame Systems with Soil Structure Interaction
    (Gazi Univ, 2020) Kara, Dondu; Bozdogan, Kanat Burak; Keskin, Erdinc
    In this study, the change of periods of planar frames by considering the soil-structure interaction is examined. For this aim, 5 different soil classes which representing in Turkey seismic code are considered. In this study, the suitability of using simplified methods for free vibration analysis of structure-soil interaction was investigated. Free vibration analysis of a typical frame system was carried out with four different approaches for five different soil classes and the results were compared. In the first model, the soil was modeled with shell elements using SAP2000 software. In the second model, SAP2000 was used again, but the soil was represented by equivalent columns. In the third model, the frame and shell are modeled with the equivalent shear beam approach. Lateral stiffness matrices and mass matrices of this model were created by the help of SCILAB software and periods were obtained. The fourth model is based on the assumption that the structure and soil are uniform throughout the building height and soil layers.In the fourth model, a practical equation in the literature was applied to the sample and the natural vibration periods were obtained for five different soil classes. At the end of the study, the results were evaluated.