Passive Vibration Control Synthesis of Power Transmission Tower Using ANSYS: Part II - Control of Seismic Response

Transcription

1 Passive Vibration Control Synthesis of Power Transmission Tower Using ANSYS: Part II - Control of Seismic Response Huang Li-Jeng 1, Lin Yi-Jun 1 Associate Professor, Department of Civil Engineering, National Kaohsiung University of Applied Science, 80778, Taiwan, Republic of China Master Student, Institute of Civil Engineering, National Kaohsiung University of Applied Science, 80778, Taiwan, Republic of China Abstract This paper presents passive vibration control synthesis of power transmission tower subjected to earthquake excitations using ANSYS along with APDL. The self-supporting power transmission tower members are modelled using BEAM-4 elements, while the added-mass, added-damping and added-tendon are modelled using MASS- 1, COMBIN-14, LINK-10, respectively, and the same as using for free vibration suppression test in Part I. APDL of ANSYS is coded for passive control tests for two typical earthquake ground accelerations, 1940 El Centro and 1995 Kobe earthquakes. A typical 345 KV self-supporting transmission tower structure modeled by totally 1179 BEAM- 4 elements along with 495 nodes is taken as numerical example. Results indicate that added damping is the most effective for vibration suppression of power transmission tower due to seismic excitation. Keywords ANSYS, APDL, Power Transmission Tower, Passive Vibration Control, Seismic Responses I. INTRODUCTION Electric power transmission towers are important apparatus in modern cities and towns related to energy supply, industrial manufacture and economic development. However, these towers are sensitive to earthquake shaking and maybe collapse if subjected to tremendous seismic acceleration. Lei and Chien (005 conducted seismic analysis of transmission towers considering both geometric and material nonlinearities [1], Shi et al. (006 conducted shaking table tests of Coupled System of Transmission Lines and Tower []. On the application of numerical analysis to transmission tower systems, Chao and Kin (004 investigated the effects of three different structural models including space truss, space frame and beam-rod structure, on the dynamic behavior of tower frame structures [3]; Zhu et al. (006 employed SAP000 and FEM to study the dynamic responses of power transmission tower under different seismic ground accelerations considering the randomness of earthquakes [4]; Luo et al. (010 employed ANSYS to study the dynamic properties of drum-shape power transmission tower using 3D FEM model and obtain natural frequencies, natural modes as well as acceleration responses due to seismic excitation [5]. Recently, Huang and Lin (014 reported a paper on the free vibration and seismic responses of power transmission tower using ANSYS and SAP000 [6]. Many passive or active control strategies have been employed for vibration control of bridges and buildings [7]. On the application of active control schemes to power transmission-line system, Chen et al. (007 studied the use of magneto-rheological dampers [8], visco-elastic damper [9]. Xu and Chen (008, Chen et al. (010 proposed the use of friction dampers [10-1]. Zhang et al. (013 considered the use of pounding TMD [13]. Recently, Chen et al. (014 presented a state-of-the-art review on the dynamic response and vibration control of the transmission tower-line system [14]. This paper presents passive vibration control synthesis of transmission tower frame subjected to 1940 El Centro and 1995 Kobe earthquake, respectively. Maximal displacements, velocities and accelerations are reported and discussed. 4

2 II. DYNAMICS MODEL OF A POWER TRANSMISSION TOWER FRAME A. Problem Description A typical 345 KV self-supporting transmission tower structure is shown in Fig. 1 of Ref. [15]. The vertical tower frame is with 50 m height and rectangular base with width 10. m. B. Basic Assumptions The basic assumptions of structural analysis of the transmission tower frame are the same in Part I of Ref. [15]. C. Finite Element Models In this research we also employ ANSYS to build up the finite element model of the transmission tower structure using BEAM-4 elements [16]. D. Passive Controlled Dynamic Equations of Transmission Tower System Subjected to Ground Acceleration If we add additional inertia, damping or stiffness elements onto the overall power transmission tower, the dynamic system equations can be described as ([ M s ] [ Ma ]{ x( t} [ Ca ]{ x ( t} ([ Ks ] [ Ka ]{ x( t} ([ M s ] [ Ma ]{ ag ( t} (1 Where [ M a ], [ C a ], [ Ka ] denotes mass, damping and stiffness matrices corresponding to additional masses, additional damping and additional tendons for passively vibration control, respectively. These control strategies can be designed separately and the same as in the Part I, Ref. [15]. III. NUMERICAL EXAMPLE AND RESULTS A. Case Description A typical transmission tower frame with totally height 50 m and base width 10. m, made of the Q345 L-shape structural steel members with the same sizes and properties as Ref. [15]. Totally 1184 BEAM4 elements with 495 degrees of freedom (each member has 6 degrees of freedom are employed. B. Passively Control of Seismic Responses of 1940 EL Centro Ground Acceleration The analysis is conducted using ANSYS along with the APDL coded by the authors as shown in Appendix. Numerical results are discussed as follows: 43 (1 Additional Masses: Typical results of effect of added-mass on the acceleration responses of power transmission tower can be observed in Fig.. The results of maximal dynamic responses due to additional masses are summarized in Table II. It can be noticed that maximal acceleration is reduced by the additive masses. ( Additional Damping: Typical results of effect of additional damping on the velocity responses of power transmission tower can be observed in Fig. 3. The results of maximal dynamic responses due to additional dashpot are summarized in Table III. It can be noticed that maximal velocity is reduced by the additive damping along with smaller decaying vibrating amplitudes. (3 Additional Stiffness: Typical results of effect of additional steel tendon on the displacement responses of power transmission tower can be observed in Fig. 4. The results of maximal dynamic responses due to additional tendon are summarized in Table IV. The effect of restoring displaced tower frame is not obvious. C. Passively Control of Seismic Responses of 1995 Kobe Ground Acceleration Similarly, typical results of effect of added-mass, addeddamping and added-tendon on the acceleration, velocity and displacement responses, respectively, of power transmission tower due to 1995 Kobe earthquake can be observed in Fig. 4 to Fig. 6. The results of maximal dynamic responses due to these three control strategies are summarized in Table IV to Table VI. It can also be noticed that maximal acceleration is reduced by the additive masses, maximal velocity is reduced by the additive damping but the effect of restoring displaced tower frame is not obvious. IV. CONCLUSION Passive vibration control synthesis of typical power transmission tower frame subjected to earthquake ground acceleration has been conducted using ANSYS along with APDL. Three control techniques: added-mass, added damping and added stiffness, are studied for two ground accelerations, 1940 El Centro and 1995 Kobe, respectively. The results indicate that among three passive control strategies technique of added damping is the most effective for seismic responses of power transmission tower.

3 REFERENCES [1] Y. H. Lei and Y. L. Chien, 005. Seismic Analysis of Transmission Towers Considering Both Geometric and Material Nonlinearities, Tamkang J. of Sci. and Engng., 8(1, 9-4. [] W. L. Shi, H. N. Li, and L. G. Jia, 006. Shaking Table Test of Coupled System of Transmission Lines and Tower, J. Engng Mech., 3(5, [3] D. S. Chao and S. A. Kin, 004. Effection of Finite Element Models for Dynamic Characteristics Analysis of Transmission Tower Structure, J. Spec. Struct., 1(3. [4] B. L. Zhu, W. T. Hu, and C. X. Li, 006. Estimating seismic responses of transmission towers by finite element method, J. Earth. Engng. and Engng. Vib, 6(5. [5] L. Luo, B. Y. Liu, and Z. H. Niu, 010. Research on the Dynamic Properties of Drum-Type Transmission Tower, J. Indus. Archi., S1. [6] L. J. Huang and Y. J. Lin, 014. Free Vibration and Seismic Responses of Power Transmission Tower Using ANSYS and SAP000, Int.. J. Emerg. Tech. and Advan. Engng, 4(8, [7] H. H. E. Leipholz and M. Abdel-Rohman, Control of Structures, Martinus Nijhoff Publishers. [8] B. Chen, J. Zeng and W. L. Qu, 007. Wind-Induced Vibration Control of Transmission Tower Using Magneto-rheological Dampers, Proc. Int. Con. Heal. Monit. Struct. Mat. and Env, 1, 33-37, Nanjing, China. [9] B.Chen, J. Zheng and W. L. Qu, 007. Practical Method for Wind- Resistant Design of Transmission Tower-Line System y Using Visco-elastic Dampers, Proc. nd Int. Con. Struct. Cond. Assess., Monit. and Impr, , Changsha, China. [10] Y. L. Xu and B. Chen, 008. Integrated Vibration Control and Health Monitoring of Building Structures Using Semi-Active Friction Dampers: Part I-Methodology, Engng. Struct., 30(7, [11] B. Chen and Y. L. Xu, 008. Integrated Vibration Control and Health Monitoring of Building Structures Using Semi-Active Friction Dampers: Part II-Numerical Investigation, Engng. Struct., 30(3, [1] B. Chen J. Zeng and W. L. Qu, 010. Vibration Control and Damage Detection of Transmisssion Tower-Line System Under Earthquake by Using Friction Dampers, Proc. 11 th Int. Symp. Struct. Engng., , Guangzhou, China. [13] P. Zhang, G. B. Song, H. N. Li and Y. X. Lin, 013. Seismic Control of Power Transmission Tower Using Pounding TMD, J. Engng. Mech., 139(10, [14] B. Chen, W. H. Guo, P. Y. Li and W. P. Xie, 014. Dynamic Response and Vibration Control of the Transmission Tower-Line System: A State-of-the-Art Review, The Sci. World J., Article ID [15] L. J. Huang and Y. J. Lin, 014, Passive Vibration Control Synthesis of Power Transmission Tower Using ANSYS, Int.. J. Emerg. Tech. and Advan. Engng, 4(9, (submitted. [16] E. Hinton and D. R. J. Owen, An Introduction to Finite Element Computations, Pineridge Press, U.K. Appendix: APDL for seismic response *SET, NT, 1000 *SET, DT, 0.0 *DIM, AC,, NT /INPUT, ELCENTRO,txt FINISH /SOLU D, 467, ALL,,,,,, D, 47, ALL,,,,,, D, 480, ALL,,,,,, D, 488, ALL,,,,,, ANTYPE, TRANS TRNOPT, FULL NSUBST, 1,,,1 OUTRES, ALL, ALL *DO, I, 1, NT ACEL, 0, 0, AC(I TIME, I*DT SOLVE *ENDDO FINISH /POST6 NSOL,, 40, U, Z, UZ DERIV, 3,, 1,,VZ40,,, DERIV, 4, 3, 1,, ACCZ40,,, /GRID, 1 /AXLAB, X, TIME ( /AXLAB, Y, DISPLACEMENT (m PLVAR, /AXLAB, Y, VELOCITY (m/ PLVAR, 3 /AXLAB, Y, ACCELERATION (m/s^ PLVAR, 4 PRVAR,, 3, 4 44

4 Table I maximal seismic responses of transmission tower without and with added-masses under 1940 el centro ground acceleration Ma (kg u max ( m 0 (uncontrolled Table II maximal seismic responses of transmission tower without and with added-dampings under 1940 el centro ground acceleration Ca ( N s / m u max ( m 0 (uncontrolled Table III maximal seismic responses of transmission tower without and with added-tendon under 1940 el centro ground acceleration (m u max ( m A sa 0 (uncontrolled Table IV maximal seismic responses of transmission tower without and with added-masses under 1995 kobe ground acceleration Ma (kg u max ( m 0 (uncontrolled Table V maximal seismic responses of transmission tower without and with added-dampings under 1995 kobe ground acceleration Ca ( N s / m u max ( m 0 (uncontrolled Table VI maximal seismic responses of transmission tower without and with added-tendon under 1995 kobe ground acceleration (m u max ( m A sa 0 (uncontrolled

5 (a Uncontrolled (Ma = 0 kg (b Added-mass Ma = 375 kg (c Added-mass Ma = 936 kg (d Added-mass Ma = 187 kg Figure 1 Effect of added-mass on the acceleration responses of power transmission tower subjected to 1940 El Centro ground acceleration 46

6 (a Uncontrolled (Ca = 0 N s / m (b Added-damping (Ca = N s / m (c Added-damping (Ca = N s / m (d Added-damping (Ca = N s / m Figure Effect of added-damping on the velocity responses of power transmission tower subjected to 1940 El Centro ground acceleration 47

7 (a Uncontrolled (Asa = 0 m (b Added-tendon (Asa = m (c Added-tendon (Asa = m (d Added-tendon (Asa = m Figure 3 Effect of added-tendon on the displacement responses of power transmission tower subjected to 1940 El Centro ground acceleration 48

8 (a Uncontrolled (Ma = 0 kg (b Added-mass Ma = 375 kg (c Added-mass Ma = 936 kg (d Added-mass Ma = 187 kg Figure 4 Effect of added-mass on the acceleration responses of power transmission tower subjected to 1995 Kobe ground acceleration 49

9 (a Uncontrolled (Ca = 0 N s / m (b Added-damping (Ca = N s / m (c Added-damping (Ca = N s / m (d Added-damping (Ca = N s / m Figure 5 Effect of added-damping on the velocity responses of power transmission tower subjected to 1995 Kobe ground acceleration 50

10 (a Uncontrolled (Asa = 0 m (b Added-tendon (Asa = m (c Added-tendon (Asa = m (d Added-tendon (Asa = m Figure 6 Effect of added-tendon on the displacement responses of power transmission tower subjected to 1995 Kobe ground acceleration 51