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Investigating the coefficient of behavior of steel bending frames equipped with rotational friction dampers

Number of pages: 174 File Format: word File Code: 31412
Year: 2014 University Degree: Master's degree Category: Civil Engineering
Tags/Keywords: Behavior coefficient of the structure - Bending frames - damper - Friction dampers - Rotational friction dampers - Steel bending frames - structure - Vibrations of the structure
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  • Summary of Investigating the coefficient of behavior of steel bending frames equipped with rotational friction dampers

    Dissertation for Master's Degree

    Civil Engineering Department, Structural Orientation

    Abstract

    Today, in earthquake-prone countries, it is recommended to use a variety of energy-depleting tools to dissipate the energy of earthquakes on the structure. One of these tools is rotational friction dampers. Due to the fact that the current regulations do not provide a value for the coefficient of behavior of frames equipped with these dampers, this thesis tries to evaluate the effect of their use on the coefficient of behavior of steel bending frames. For this purpose, several steel bending frames with medium ductility with different number of floors have been designed according to the criteria of standard 2800 and topic 10 of the national regulations of Iran. Then, using incremental nonlinear dynamic and static analyzes with the help of Sap2000-V15 software, the coefficient of behavior and its parameters for the original frames equipped with dampers were obtained and compared with each other.

    The changes in the coefficients of increased resistance and ductility according to the results of the analysis of frames with and without dampers show that the effect of rotational friction dampers on the coefficient of increased resistance of short structures is greater than their ductility coefficient. is In higher floors, the situation is the opposite, so that the effect of the damper on the ductility coefficient is greater in proportion to the increased strength. In total, the damper increases the coefficient of behavior of steel bending frames by 60.7 and 55.23 percent, respectively, under static and dynamic nonlinear analysis.

    Key words: coefficient of behavior, rotational friction dampers, nonlinear static analysis, incremental nonlinear dynamic analysis, steel bending frames

    Chapter 1

    Introduction

    (research generalities)

     

     

     

     

    Today, the basis for the design of structural tremors is such that the structure has some possibility of plastic deformation (for example, by creating plastic joints in beams and then in columns). This action causes the loss of a large amount of energy input to the structure and finally provides the required safety. Applying this feature to structures, in addition to being uneconomical, increases the amount of damage to structures and non-structures. In order to eliminate and reduce the damage caused to the main members of the structure (beams and columns), special devices have capabilities such as depreciation of the input energy of the structure, plastic deformation and so on. They are installed in certain places. One of these types of devices are friction systems, which due to their high potential in absorbing and dissipating energy on the structure, as well as the low cost of installing and maintaining them, have been used in various applications in civil engineering, especially the structure.

    According to the tendency of designers to analyze and design structures using an equivalent static method due to its ease and low cost, most of the current regulations have made this method the basis of design. Although, in the current regulations, especially Iran's 2800 standard, there is a glimpse of the non-linear design method and they want to guide the users towards the non-linear design. Anyway, the basis of current earthquake design for conventional structures is elastic analysis before nonlinear analysis.

    In elastic design, the linear design force of the building is obtained from a linear spectrum that depends on the natural period of the building and the soil conditions of the building site, and to take into account the nonlinear effect and energy loss due to the hysteretic behavior, damping, and the effect of increasing resistance of the structure, this linear force is converted into the design force by modifying the behavior of the structure (behavior coefficient).

    1-1. Necessity of research

    In the current regulations that are based on linear analysis (such as Iran's standard 2800), the coefficient of behavior is presented for all types of conventional buildings, but there is no mention of the coefficient of behavior of other structural systems, especially the structures that are the subject of this research (structures equipped with rotational friction dampers). Perhaps the reason for this is that the design principles of such structures are different according to their application. For example, friction dampers, by increasing the damping and wasting energy input to the structure, lead to a reduction in the structure's requirement. Also, by increasing its lateral stiffness, they increase the capacity of the structure. For this reason, the design method of structures equipped with these dampers is usually done by the capacity spectrum method and non-linear methods. Of course, with the help of elastic design, by determining the effective stiffness of the damper with a trial and error test, such structures can also be designed.Therefore, it seems that by having a primary criterion such as the coefficient of behavior, it provides the designer with the possibility to make a quick and initial assessment of newly built structures equipped with dampers, to determine their initial stages. Also, in the discussion of retrofitting existing buildings, in order to control the effect of the damper on the capacity of sections, it seems useful to have such a standard.

    1-2. Objectives

    As mentioned above, in the current regulations and researches, the behavior coefficient for the discussed structures is not provided. Although the proposed behavior coefficients for common structures are not accurate enough. The important issue in this discussion is to compare it with the values ??of the coefficients obtained for the primary frames after calculating and estimating the values ??of ductility and added strength (as important parameters of the behavior coefficient) as well as the behavior coefficient of structures equipped with rotational friction dampers. In general, it is not possible to consider the same coefficient of increasing resistance and ductility for one type of structure and for all its period ranges. These values ??depend on the type of structure and the characteristics of its frame.

    In structures equipped with energy dissipation devices, due to the fact that dampers with different capacities are used according to their needs in the building, their effect on damping and absorption and energy loss and hysteretic behavior of the structure is also variable, and as a result, the values ??of ductility coefficients and additional resistance are also variable.

    In this research, the behavior coefficient of steel bending frames with medium ductility equipped with Rotational friction dampers with conventional capacity (recommended by regulations) are calculated and compared with the coefficient of behavior of primary structures and the effect of these dampers on the parameters governing the coefficient of behavior is measured. 1-3. Assumptions

    In this research, the investigation of the coefficients of ductility, added strength and overall behavior of the structure was carried out on steel bending frames with medium ductility with and without rotational friction dampers and in two-dimensional space without the effect of twisting. The construction site of the building was considered to be in the area with a high risk level of earthquakes and on type 4 soil. BOX (for columns) and IPE (for beams) standard sections were used for structural members. Circular solid sections are used for braces.

    Modeling in Sap2000 (V-15) software is macro. In this way, beams, columns and damper plates were modeled with the help of linear elements. The nonlinear link available in this software was used to model the torsional stiffness of the damper. Finally, for non-linear static and dynamic analysis, the automatic plastic joints of Sap2000 software have been used to introduce the plastic joints of the members.

    1-4. Research method

    The history of friction dampers and how they work are discussed in the second chapter. Then, the introduction of rotational friction dampers, including their accessories and behavior mechanism, is discussed and finally, the important researches that have been done in this field are mentioned. In the third chapter, the basics of determining the behavior coefficient and the importance of its use in the structure are examined. The parameters affecting this coefficient are introduced, such as force reduction coefficients due to ductility and increased resistance, and at the end of the chapter, similar researches are mentioned regarding the determination of the coefficient of behavior of frames equipped with additional dampers.

    The fourth chapter introduces the studied frames and the design assumptions of the structures in this research. Also, how to model rotational friction dampers, including determining their capacity and moment-angle behavior, has been described in detail. The basics of non-linear static and dynamic analyzes and the final state of the structure's performance are among the other things discussed. The fifth chapter includes how to calculate the behavior coefficient and its parameters (force reduction coefficient due to ductility and increased resistance coefficient) using nonlinear static and dynamic methods in this research. The ductility and increased strength of each of them have been presented and compared with each other. After reviewing the results, in order to compare the behavior coefficients of the primary frames calculated in this research and its stated value in the regulations, the correction coefficient of the numerical model was introduced. With the help of this parameter, the behavior coefficients obtained for the initial frames were modified and compared with the corresponding value of its regulations.

  • Contents & References of Investigating the coefficient of behavior of steel bending frames equipped with rotational friction dampers

    List:

    List of tables D

    List of diagrams G

    List of images and figures. I

    Chapter One: Introduction (general research)

    1-1. Necessity of research. 3

    1-2. Goals. 4

    1-3. Assumptions. 4

    1-4. Research method. 5

    Chapter Two: Introduction to rotational friction dampers

    2-1. Introduction. 8

    2-2. Friction dampers. 9

    2-3. History and types of friction dampers. 10

    2-4. Introduction of rotational friction dampers. 23

    2-4-1. Damping components. 23

    2-4-2. Damping mechanism. 24

    2-4-3. The history of studies conducted on rotational friction dampers. 25

    Chapter three: Theoretical foundations of determining the coefficient of behavior structures

    3-1. Introduction. 50

    3-2. History of behavior factor 51

    3-3. Methods of calculating behavior coefficient 53

    3-3-1. Calculation of behavior coefficient by the method of Young's plasticity coefficient. 53

    3-3-2. General plasticity coefficient of the structure. 59

    3-3-3. Reduction factor due to plasticity. 60

    3-3-4. More resistance. 63

    3-4. Studies conducted on the coefficient of behavior of frames equipped with various types of dampers. 66

    Chapter Four: Software modeling of bending steel frames equipped with rotational friction dampers

    4-1. Introduction. 71

    4-2. Introduction of studied models. 71

    4-3. Loading and designing sections. 73

    4-3-1. Gravitational loading. 74

    4-3-2. Earthquake loading. 74

    4-4. Analysis and design of models 75

    1-4-4. Control of sections in terms of local buckling for bending. 75

    4-4-2. Determining the cutting coefficient of the design base. 77

    3-4-4. Design criteria control. 77

    4-4-4. Control of relative lateral displacement of floors. 79

    4-5. The method of software modeling of rotational friction dampers and its verification. 84

    1-5-4. Steps to determine the behavior of the moment-damper angle. 86

    4-5-2. Validation of software modeling of a structure equipped with a damper. 89

    4-6. Determining the capacity of dampers for modeling. 94

    4-7. Nonlinear static analysis of structures 98

    4-8. Incremental nonlinear dynamic analysis of structures 99

    4-9. Final status and submission of software analysis. 102

    4-9-1. Definition of the final state of the structure behavior according to the 2800 standard guidelines. 103

    4-9-2. The final state of the structure according to the FEMA356 guidelines. 105

    4-9-3. Definition of the surrender status of the structure. 112

    Chapter Five: Determining the coefficient of behavior of steel bending frames with and without rotational friction dampers

    5-1. Introduction. 114

    5-2. Reduction factor due to ductility. 115

    5-2-1. Calculation of force reduction factor due to plasticity. 116

    5-3. Calculation of additional resistance coefficient of the structure 118

    Sixth chapter: results and suggestions

    6-1. Introduction. 127

    6-2. General review of the obtained results 127

    6-2-1. Nonlinear static analysis results. 128

    6-2-2. Results of incremental nonlinear dynamic analysis. 130

    6-3. The effect of the height of the structure on the coefficient of behavior 133

    4-6. The effect of the damper on the coefficient of behavior of the structure 133

    6-5. Overall result. 134

    6-6. Numerical model correction factor. 136

    6-7. Suggestion for future research 139

    List of references

    Appendix A: Matlab code to calculate the behavior of rotational friction damper. 1

    Appendix B: Matlab code for idealization of increasing curves and calculation of behavior factor of structures 5

     

    Source:

    [1]-Chopra, A. K., ed. 2012. Dynamics of Structures. Theory and Applications to Earthquake Engineering.

    [1]- Vice President of Planning and Strategic Supervision, 2019 "Guide to the methods and methods of improving the earthquakes of existing buildings and implementation details". Tehran, publication number 524. [1] Soong, T. T., Constantinou, M. C., ed. 1994. Passive and Active Structural Vibration Control in Civil Engineering, Cism Courses and Lectures, Springer, New York.

    [1]-Soong, T. T., Dargush, G. F., 1997. Passive Energy Dissipation Systems in Structural Engineering, Wiley, New York.

    [1]-Keightley, W., 1977. Building Damping by Coulomb Friction. 6th Wcee, New Delhi, India, 3043-3048.

    [1]-Keightley, W., 1979. Prestressed Walls for Damping Earthquake Motions in Buildings. Montana State University, Dept. Of Civil Engineering and Mechanics.

    [1]-Pall, A., Marsh, C.Fazio, P., 1980. Friction Joints for Seismic Control of Large Panel Structures. PCI Journal, 25 (6), 38-61.

    [1]-Pall, A., Marsh, C., 1982. Seismic Response of Friction Damped Braced Frames. JSDEAG, 108(6), 1313-1323.

    [1]-Filiatrault, A., Cherry, S., 1987. Performance Evaluation of Friction Damped Braced Steel Frames Under Simulated Earthquake Loads. EERI, 3(1), 57-78.

    [1]-Aiken, I., Kelly, J., Pall, A., 1988. Seismic Response of A Nine-Story Steel Frame with Friction Damped Cross-Bracing. Rep. No. Ucb/Eerc-88/17, University of California, Berkeley, Ca.

    [1]-Aiken, I. D., Kelly, J. M., 1990. Earthquake Simulator Testing and Analytical Studies of Two Energy-Absorbing Systems for Multistory Structures. Rep. No. Ucb/Eerc-90/03, University of California, Berkeley, Ca.

    [1]-Fitzgerald, T. F., Anagnos, T., Goodson, M., Zsutty, T., 1989. Slotted Bolted Connections in Aseismic Design for Concentrically Braced Connections. EERI, 5 (2), 383-391.

    [1]-Grigorian, C. E., Popov, E. P., 1993. Slotted Bolted Connections for Energy Dissipation. Proc., Atc-17-1 Seminar on Seismic Isolation, Passive Energy Dissipation and Active

    [1]-Constantinou, M., Reinhorn, A., Mokha, A., Watson, R., 1991. Displacement Control Device for Base Isolated Bridges. EERI, 7 (2), 179-200.

    [1]-Constantinou, M. C., Kartoum, A., Reinhorn, A. M., Bradford, P., 1991. Experimental and Theoretical Study of a Sliding Isolation System for Bridges. Rep. No. Nceer 91-0027, National.

    [1]-Pall, A., Pall, R. T., 2004. Performance-Based Design Using Pall Friction Dampers - an Economical Design Solution. Proc. 13th World Conference on Earthquake Engineering, Vancouver, B. C., Canada.

    [1]-Nishitani, A., Nitta, Y., Ishibashi, Y., Itoh, A., 1999. Semi-Active Structural Control with Variable Friction Dampers. Proc., American Control Conference, Aacc, Dayton, Oh, 1017-1021.

    [1]-Mualla, I. H., 2000a. Experimental Evaluation of a New Friction Damper Device", 12th World Conference on Earthquake Engineering, Auckland, New Zealand.

    [1]- Mualla, I. H., 2000b. Parameters Influencing the Behavior of a New Friction Damper Device. Spie's 7th International Symposium on Smart Structures & Materials, SS2000, Ca, USA, 2000.

    [1]-Nielsen, L. Mualla, I., 2002. A Friction Damping System Low Order Behavior and Design. Report Byg·Dtu,R-0302002, ISSN 1601-2917, ISBN 87-7877-090-4

    [1]-Mualla, I., Belev, B., 2002. Performance of Steel Frames With a New Friction Damper Device under Earthquake Excitation. JCSR, 24, 365-371

    [1]-Mualla, I., Nielsen, L. O., Belev, B., Liao, W. I., Loh, C. H., Agrawal, A., 2002. Performance of Friction-Damped Frame Structure: Shaking Table Testing and Numerical Simulations. 7th US. National Conference on Earthquake Engineering, Boston, USA.

    [1]-Mualla, I., Nielsen, L. O., Belev, B., Liao, W. I., Loh, C. H., Agrawal, A., 2002. Numerical Predictions of Shaking Table Tests on a Full Scale Friction-Damped Structure. 12th European Conference on Earthquake Engineering .Paper Reference 190.

    [1]-Mualla, I., Nielsen, L. O., Chouw, N. Belev, B., Liao, W. I., Loh, C. H., 2002. Enhanced Response through Supplementary Friction Damper Devices.

    [1]-Liao, W. I., Mualla, I. Loh, C. H., 2004. Shaking-Table Test of a Friction-Damped Frame Structure the Structural Design of Tall and Special Buildings. Wiley Interscience [Online]. 13, 45–54, (June 9, 2004). http://www.interscience.wiley.com/10.1002/Tal.232

    [1]-Mualla, I., Nielsen, L. O., Viviani, L. Briseghella.Dynamic Response of RC Frame with a New Friction Damper Device.

    [1]-Vaseghi Amiri, J., Naghipoor, M., Jalali, S. G., 2008. Performance of Rotational Friction. Damper (RFD) in Steel Frames. The 14th World Conference on Earthquake Engineering. October 12-17, Beijing, China.

    [1]-Filiatrault, A., Cherry, S., 1989

Investigating the coefficient of behavior of steel bending frames equipped with rotational friction dampers
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