STUDY AND APPLICATION OF METALLIC YIELDING ENERGY DISSIPATION DEVICES IN BUILDINGS

Transcription

1 10NCEE Tenth U.S. National Conference on Earthquake Engineering Frontiers of Earthquake Engineering July 21-25, 2014 Anchorage, Alaska STUDY AND APPLICATION OF METALLIC YIELDING ENERGY DISSIPATION DEVICES IN BUILDINGS Hong-Nan Li 1, Gang Li 2 and Su-Yan Wang 3 ABSTRACT Three types of metallic yielding energy dissipation devices, named as round-hole metallic damper, double X-shaped metallic damper and metallic yielding-friction damper are presented. Quasi-static tests with scale models of the metallic dampers specimens were carried out, respectively. The test results clearly reveal that these dampers not only have certain stiffness and but also good capacity of energy dissipating. The simplified design procedure for the structure with these energy dissipation devices was summarized. Above three types of metallic dampers were designed based on the procedure and applied in actual structures to improve initial stiffness of original structural under normal use or frequency earthquake and to dissipate inputting energy during great earthquake. In addition, numerical models were established using finite element software and dynamic response comparison of the structures with and without these metallic yielding energy dissipation devices were conducted. 1 Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian, Liaoning Province China. hnli@dlut.edu.cn 2 Associate Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Institute of Earthquake Engineering, Dalian, Liaoning Province China. gli@dlut.edu.cn 3 Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian, Liaoning Province China. suyanw@dlut.edu.cn

2 STUDY AND APPLICATION OF METALLIC YIELDING ENERGY DISSIPATION DEVICES IN BUILDINGS Hong-Nan Li 1, Gang Li 2 and Su-Yan Wang 3 ABSTRACT Three types of metallic yielding energy dissipation devices, named as round-hole metallic damper, double X-shaped metallic damper and metallic yielding-friction damper are presented. Quasi-static tests with scale models of the metallic dampers specimens were carried out, respectively. The test results clearly reveal that these dampers not only have certain stiffness and but also good capacity of energy dissipating. The simplified design procedure for the structure with these energy dissipation devices was summarized. Above three types of metallic dampers were designed based on the procedure and applied in actual structures to improve initial stiffness of original structural under normal use or frequency earthquake and to dissipate inputting energy during great earthquake. In addition, numerical models were established using finite element software and dynamic response comparison of the structures with and without these metallic yielding energy dissipation devices were conducted. Introduction The traditional approach to seismic design has been based upon providing a combination of strength and ductility to resist the imposed loads. Thus, the level of the structural security cannot be achieved, because the disadvantage of the designing method is lack of adjusting capability subjected to an uncertain earthquake. However, the appearance of passive energy dissipation provides a new way to solve above problem and is now widely used in many parts of the world. The structural response can be reduced when subjected to wind and earthquake by mounting passive energy dissipation devices into the buildings, thereby reduces energy-dissipating demand on primary structural members and minimizes possible structural damage. Contrary to semiactive and active systems, there is no need for an external supply of power. Since the devices does not require an external power and are inexpensive, significant effort has gone towards developing them with the large ductility and high energy dissipation capability by utilizing different mechanisms. In addition, theoretical researches have made a great progress, such as the passive energy dissipation devices distributions and parameters optimum problems [1-8]. The inelastic deformation of metallic is an effective mechanism for input earthquake energy dissipation. In addition, metallic is also a popular and inexpensive choice for an energy 1 Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian, Liaoning Province China. hnli@dlut.edu.cn 2 Associate Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Institute of Earthquake Engineering, Dalian, Liaoning Province China. gli@dlut.edu.cn 3 Professor, Faculty of Infrastructure Engineering, Dalian University of Technology, Dalian, Liaoning Province China. suyanw@dlut.edu.cn

3 dissipation device because of its relatively high elastic stiffness, good ductility and high potential for dissipating energy in the post-yield region. Thus, the metallic yielding energy dissipation device (also named metallic yielding dampers, MYDs), as a well-known passive energy dissipation device, its effectiveness and low cost are now well recognized and extensively tested in the past in civil engineering. The idea of utilizing separate metallic dampers in the structures to absorb a large portion of the seismic energy began with the conceptual and experimental work by Kelly [9]. Then, numerous of various types of energy-absorbed metallic devices have been proposed, i.e. X-shaped and triangular plate metallic dampers [10,11]. During their service period, they provide the initial stiffness without the energy dissipation until yielding, it also means that the energy dissipation does not occur until the yield force exceeded. Ordinary metallic damper is dependent on its out-of-plane bending deformation so that provide additional damping for structures, even to reduce dynamic response of structure subjected to environmental loadings. The advantage of this deformation mechanics is uniform distribution along the full height of the steel plate. However, inelastic deformation of conventional metallic damper probably occurs when it is subjected to a relatively small disturbance (wind or earthquake), since its out-of-plane stiffness is relatively low. As a result, it has to be replaced after the disturbance. Certainly, the PEDDs also have shortcomings, such as the added stiffness reduces displacement while increasing base shear and acceleration prior to yielding. After a series of theoretical and experimental researches, more and more interests and attentions are turned on the application of metallic dampers in actual projects [12-16]. In this paper, three types of metallic yielding energy dissipation devices were presented. Tests for scale and full-scale models of these metallic dampers were conducted, the experimental results validate the metallic dampers have good energy dissipation capacity. They were applied in actual buildings and numerical analysis results show the effectiveness of these metallic dampers. Experimental Study on Metallic Yielding Energy Dissipation Devices Metallic yielding dampers take advantage of the inelastic deformation of metallic materials under the time-dependent cyclic loading for dissipating the input earthquake energy. They can broadly be classified into two categories: (1) the shear type metallic yielding damper with a number of openings is subjected to in-plane shear deformations and energy is dissipated through the shear plastic yielding of metallic yielding plates, such as the honeycomb damper, slit damper and single round hole damper; (2) the bending type metallic damper utilizes flexural deformation of metallic plates under the out-of-plane bending, such as the ADAS, triangular metallic damper. Round-Hole Metallic Damper (RHMD) The photograph of single round-hole metallic damper is shown in Fig.1 (a). Typical hysteretic curve of the test is shown in Fig.1 (b). The experimental results indicated the single round-hole damper not only has good energy-dissipated capability, but also is of high initial stiffness. It is suitable to be as an effective energy dissipating device.

4 Fig.1 (a) Photograph of RHMD Fig.1 (b) Hysteretic curve of RHMD Double X-Shaped Metallic Damper (DXMD) A photograph of the DXMD and it hysteretic curve are illustrated in Fig. 2(a) and Fig. 2(b). Hysteretic loop curve shows that the DXMD has both large initial stiffness and energy dissipating capability. Fig. 2(a) The photograph of DXMD Fig. 2(b) Hysteretic curve of the DXMD Metallic Yielding-Friction Damper (MYFD) The construction of the MYFD turns the phased seismic design into reality easily. The seismic design philosophy for the MYFD here is that inputting energy is dissipated through friction behaviors under the small earthquake, and inputting energy is dissipated by overall MYFD inelastic behaviors under the large earthquake. It can be observed from the MYFD construction that the length of sliding way is the best dividing for these two phases. Figure 3(a) and Figure 3(b) shows the photograph of model and deformed MYFD. Fig. 3(a) The photograph of MYFD Fig. 3(b) The photograph of deformed MYFD

5 Fig.4(a) Hysteretic loops of friction behavior. Fig. 4(b) Hysteretic loops of whole process Design Principles For Structures With MYDs In order to make the design of the structures with MYDs standardized and rationalized, it is necessary to formulate design guidelines and procedures. Refering to the design considerations presented by Soong et al. [17], the procedure was established as follows: (1) Design structures without MYDs in considering the corresponding loading actions. (2) Compute the lateral stiffness and yielding displacement of each floor. (3) Select a suitable ratio of the inter-story stiffness to MYDs stiffness, which can be expressed by K = ( SR) K (1) in which Kd represents the stiffness of the MYD; K f is the stiffness of inter-story. The yielding displacement of MYDs gives d Δ = αδ f y yf (2) The value of parameter α is less than 2/3 obtained in China Seismic Code [18]. (4) Perform dynamic analysis of the structure with the MYDs to earthquake ground motions. Steel Framed Structure Application in Actual Buildings A steel framed structure with eight stories shown in Fig. 5(a) is located in China. Overall finite element model of the structure is shown in Fig. 5(b). The DXMDs are installed on the each floor of the steel structure due to overall weak stiffness of this structure in Y direction. The seismic protection intensity of the steel structure is degree Ⅶ, and the site soil belongs to the type Ⅱ (medium hard soil) based on the China Seismic Code [18]. The La - Baldwin Hills record (Northridge earthquake, 17/1/1994), which peak are adjusted to 220 cm/s 2 are inputted in two dimensions of the steel structure, i.e. X and Y directions.

6 Fig.5(a). The steel building with DFMDs Fig.5(b) Overall finite element model The dynamic analyses of this building with and without DXMDs are carried out individually. Figure 6(a) and Figure 6(b) shows the displacement responses of the structure. The results indicate that the DXMDs are effective dissipation devices. Fig.6(a) Displacement response of base floor Fig.6(b) Displacement response of top floor Reinforced Concrete Framed Structure #1 A reinforced concrete (RC) framed building shown in Fig.7 is located on the campus of Dalian University of Technology in China. The base floor of this building contains the laboratory of hydraulic dynamics to simulate ocean waves, which generates inter-story drift when functioning. In order to reduce the seismic response of inter-story drift, the RHMD and DXMDs were applied. The seismic protection intensity on this building site is Ⅵ degree, and the site soil belongs to the type Ⅱ. Fig.7. RC framed building

7 The DFMDs are fixed on the nodes between beams and braces. In the installing process, the upper side of the DFMDs is welded on the level steel plate embedded in beams, and the lower end of the DFMDs are welded on another level steel plate, which is attached to the braces. The installed DFMDs are shown in Fig.8. Fig.8 (a). Photograph of RHMD Fig.8 (b). Photograph of DXMD The dynamic responses of the building subjected to the earthquake excitations shown in Fig.19 are analyzed using ANSYS program. The results given in Fig. 9 show the displacement responses of the structure with and without the dampers under the Taft record. It can also be seen from these figures that the peak displacements at the base of the building without the DFMDs are approximately 52 mm in X direction which is approximately 8 times the peak displacement of the building with the dampers. Fig.9(c). Displacement in X direction Fig.9(d). Displacement in Y direction Reinforced Concrete Framed Structure #2 A RC framed building with six stories shown in Fig. 10(a) is located in the Sichuan province of China. The MYFD are installed in the building, as shown in Fig. 10(b). Three matched earthquake acceleration records are selected according to the site where the structure is located.

8 Fig.10(a). Photograph of the building Fig.10(b) The photograph of MYFD Displacement responses of structure with and without the MYFDs under the earthquakes were obtained and are summarized in Tables 1. Results show that the displacement responses have obvious reduction and the reason is that the MYFDs contribute to the additional stiffness and damping ratio. Table 1. Response of the building with and without MYFDs under earthquakes (Unit: mm) Floor Number of earthquake records Average reduction rate /20.8/27.6% 53.3/34.7/34.9% 22.1/12.0/45.5% 36.0% /39.3/26.8% 95.1/58.6/38.4% 35.8/20.4/43.0% 36.0% /56.1/23.8% 134.8/77.3/42.6% 42.4/25.4/40.0% 35.5% /66.9/25.1% 159.6/93.0/41.7% 53.2/33.1/37.7% 34.8% /71.2/26.3% 169.5/99.7/41.2% 58.9/38.4/34.8% 34.1% /72.8/26.9% 173.5/102.6/40.8% 61.3/40.8/33.4% 33.7% Note: Num1/Num2/Numb3. Num1 and Num2 represent the displacements without and with MYFDs; Num3 means reduction rate. Conclusions The inelastic feature of metallic plate is utilized to design and develop three types metallic yielding energy dissipation devices. The quasi-static test was carried out to verify the design idea presented in this study. Finally, these metallic damper were applied in an actual building to reduce the displacement response effectively. Acknowledgments Funding for authors was provided by the Science Fund for Creative Research Groups of the National Natural Science Foundation of China (Grant No ). References 1. Martinez-Romero E. Experiences on the use of supplementary energy dissipators on building structures. Earthquake Spectra 1993; 9 (3): Singh MP, Moreschi LM. Optimal placement of dampers for passive response control. Earthquake engineering & structural dynamics 2002; 31 (4): Moreschi L, Singh M. Design of yielding metallic and friction dampers for optimal seismic performance. Earthquake engineering & structural dynamics 2003; 32 (8):

9 4. Curadelli RO, Riera JD. Reliability based assessment of the effectiveness of metallic dampers in buildings under seismic excitations. Engineering structures 2004; 26 (13): Dargush G, Sant R. Evolutionary aseismic design and retrofit of structures with passive energy dissipation. Earthquake engineering & structural dynamics 2005; 34 (13): Bagheria S, Hadidi A, Alilou A. Heightwise distribution of stiffness ratio for optimum seismic design of steel frames with metallic-yielding dampers. Procedia Engineering 2011; 14: Aguirre J, Almazán J, Paul C. Optimal control of linear and nonlinear asymmetric structures by means of passive energy dampers. Earthquake Engineering & Structural Dynamics 2013; 42 (3): Guo JWW, Christopoulos C. Performance spectra based method for the seismic design of structures equipped with passive supplemental damping systems. Earthquake Engineering & Structural Dynamics 2013; 42 (6): Kelly JM, Skinner R, Heine A. Mechanisms of energy absorption in special devices for use in earthquake resistant structures. Bulletin of New Zealand National Society for Earthquake Engineering 1972; 5 (3): Whittaker AS, Bertero VV, Thompson CL, Alonso LJ. Seismic testing of steel plate energy dissipation devices. Earthquake Spectra 1991; 7 (4): Tsai KC, Chen HW, Hong CP, Su YF. Design of steel triangular plate energy absorbers for seismic-resistant construction. Earthquake Spectra 1993; 9 (3): Skinner R, Tyler R, Heine A, Robinson W. Hysteretic dampers for the protection of structures from earthquakes. Bulletin of New Zealand National Society for Earthquake Engineering 1980; 13 (1): Bartera F, Giacchetti R. Steel dissipating braces for upgrading existing building frames. Journal of Constructional Steel Research 2004; 60 (3): Mualla IH, Belev B. Performance of steel frames with a new friction damper device under earthquake excitation. Engineering Structures 2002; 24 (3): Min KW, Kim J, Lee SH. Vibration tests of 5-storey steel frame with viscoelastic dampers. Engineering Structures 2004; 26 (6): Phocas M, Pocanschi A. Steel frames with bracing mechanism and hysteretic dampers. Earthquake engineering & structural dynamics 2003; 32 (5): Soong TT, Dargush GF. Passive energy dissipation systems in structural engineering. Wiley: New York, Seismic Design Code for Buildings (GB ). China Architectural Industry Press, Beijing, 2010.