カテゴリー Ⅲ 日本建築学会構造系論文集第 82 巻第 741 号, ,2017 年 11 月 J. Struct. Constr. Eng., AIJ, Vol. 82 No. 741, , Nov., 2017 DOI

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1 カテゴリー Ⅲ 日本建築学会構造系論文集第 82 巻第 741 号, ,217 年 11 月 J. Struct. Constr. Eng., AIJ, Vol. 82 No. 741, , Nov., 217 DOI 極大地震動の入力制限をはかる直置き型構造の滑り挙動と最大ベースシア SLIPPING BEHAVIOR OF BASE SHEAR CAPPING BUILDINGS FOR COLLAPSE PREVENTION AND REQUIRED MAXIMUM STRENGTH 濱嶋郁望 *, 倉田真宏 ** ***, 中島正愛 Ikumi HAMASHIMA, Masahiro KURATA and Masayoshi NAKASHIMA This study proposes a seismic retrofit method named base shear capped building, which detaches the superstructure from foundation. The paper verifies the effectiveness of proposed system by shake table test and numerical simulation. The shake table test shows basic properties of sliding behavior. In numerical simulation, the proposed system is simplified to an SDOF system having a sliding base. In pulse type earthquakes having a magnitudes of larger than level 2, the maximum value remains at most 2.5 times of the friction coefficient. If slight ductility is permitted, the maximum base shear can be reduced to twice the friction coefficient. Keywords : Base shear capped buildings, Seismic retrofit, sliding, friction coefficient, Maximum base shear 1. Mostagel 1~2) ~4).8 5) [6] * ** *** 京都大学工学研究科建築学専攻大学院生京都大学防災研究所准教授 Ph.D. 京都大学防災研究所教授 Ph.D. Grad. Student, Graduate School of Eng., Kyoto University Assoc. Prof., DPRI, Kyoto University, Ph.D. Prof., DPRI, Kyoto University, Ph.D. 1769

2 Mortar Base Upper frame Lubber bearing Lower frame Column base Mass plates(1556kg) Beam (H ) Column (H ) Mortar base Upper mass Steel box Lower mass 15 Column base Mortar Bolts Contact element Carbon powder 1 2 3Hz Fig.1 Fig.1(a) 515kg Fig.1(b) 4 8 H Hz H kg 7578kg.7 Table1 3 SF-1SF-2SF-3.91 TTB Specimen Mass ratio(α) Natural frequency (Hz) Basic specimen SF SF SF Frame specimen TTB Fig.1(c)~(d)Fig.1(c) 25 mm 25 mm 75 mm 75 mm MPa MPa Fig.1(d) 12 mm 55 mm 55 mm Fig.1 x 4. Hz 2. Hz1.5 Hz1. Hz.5 Hz ElCentro JMA Kobe NS JMA Kobe EW 55 mm [7] 2.2 (1) ( )g (1) 177

Friction Coefficient - Dynamic fc. SF-1 SF-2 SF-3 TTB - -6-4 -2 2 4 6 Velocity (m/s) 2 4 6 8 1 Test Cases g 8) Fig.2 (a) 2m/s 2 1Hz SF-3.8 m/s Fig.2(a) 11 2m 11 Fig.2(b).16.1.4.6 5 2m.16 2.

3 Friction Coefficient - Dynamic fc. SF-1 SF-2 SF-3 TTB Velocity (m/s) Test Cases g 8) Fig.2 (a) 2m/s 2 1Hz SF-3.8 m/s Fig.2(a) 11 2m 11 Fig.2(b) m OpenSees 9) Fig.1(a) Zerolength Element 2% Fig.3(a) Elastic Column Beam Element 1 2.7% 1.5% Flat Slider Bearing Fig.3(b).16 Rigid element Elastic column Flat slider element Elastic beam.16 Mass ratio Total weight(kg) Upper mass (kg) Lower Mass (kg) Natural Freq. (Hz) Stiff. ( 1 6 N/m) SF SF SF TTB Table2 2.4 Mostaghel 1~2) (2) = = = (2) 6m/s Hz SF-1.5 Fig.4 Fig Hz 5.1 Hz (2) 5.6 Hz Fig.5(a) 8m/s Hz Fig.5(b) Fig.5(a)

4 Acc. (m/s 2 ) Hz 5.6 Hz -1 Test Numerical kn Fig.5(a) % Fig.5(b) mm 1.4% 4% 2.6 Fig.6 JMAKobeNS 4 SF-1 4%SF-2 18%SF-3 23% (2) TTB TTB 1%.9 TTB Fig.1(a) kg kg kn/m 5% % 2 (2) N/Ng Slippage (mm) N1/Ng N2/Ng mm Max. Base shear coeff. Simplif ied TTB(.9) SF-1 (.5) SF-2 (.6) 1 SF-3 (.8) TTB (.9) PGA (gal) 1 1/1 2 2 SAC ~11) SAC2 Fig.7 SAC2 2 SAC Fig.8(a) % Sa (g) Period (s) 1772

5 Max Base shear Coeff. Max Base shear Coeff PGA (m/s 2 ) La Scale Friction force (kn) 2 Sliding Amplitude Amplitude gfig.8(a) 1 m/s Fig.9(a) Fig.9(b) ()(3) 12~13) () = 1 2 ( ) () = 2 1 (3) ( 2 ) = 2 (3) (4) = ( ) (4) ( ) = 2 (5) = 2 (5) = ( ( )) = 2 g (6) g (7) = 2 (7) SAC2 Fig.8(b) SAC2 Scale Scale Fig.8(b) Scale 1773

6 2 2 la19 Fig.1 Scale1 la19 Fig.1(a) (b)fig.1(a) Fig.1(b) Fig.11 Fig.11(a) Fig.11(b)Fig.11(a) Fig.11(b) 2 2 Fig.8(b) 2 84 Scale1 Scale Scale ) kn/m % SAC2 Scale2 la19 Fig Fig Fig Deformation (m) Deformation (m) C = C = Deformation (m) Deformation (m) C = C = μ(fss) 8 84 th percentile Cy m ω 1774

7 3. 4% % SAC SAC2 2 Francesca Barbagallo Hongsong Hu 7) Barbagallo, F., Hamashima, I., Hu, H., Kurata, M., Nakashima, M.: Base Shear Capping Buildings with Graphite-Lubricated Bases for Collapse Prevention in Extreme Earthquakes, Earthquake Engineering and Structural Dynamics, 216 8) Enokida, R., Nagae, T., McCormick, J., Katsuo, M. and Nakashima, M.: Shaking Table Test on Friction Behavior Between Steel Column Base and Base Mortar, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.73, No.629, pp , 28.7 (in Japanese) pp ) Mazzoni, S., McKenna, F., Scott, M.H., Fenves, G.L. and Jeremic, B.,:OpenSEES Command Language Manual, Pacific Earthquake Engineering Research Center, University of California at Berkeley, USA, 23 1) Scawthorn, C. and Chen, W.: Earthquake Engineering Handbook, CRC Press, 22 11) Someville, P.G., Smith, N., Punyamurthula, S. and Sun, J.: Development of Ground Motion Time Histories for Phase 2 of the FEMA/SAC Steel Project. Report SAC/BD-97/4, SAC joint Venture, ) Chopra, A.K.: Response to Arbitrary, Step and Pulse Excitations, Dynamics Of Structures Theory And Applications To Earthquake Engineering second edition, Prince-Hall India, 26 13) Shibata, A.: Saishintaishinkouzoukaiseki (Dynamic Analysis of Earthquake Resistant Structures), Morikita, 23 (in Japanese) 23 14) Fardis, M.N. and Panagiotakos, T.B.: Seismic Design and Response of Bare and Masonry-Infilled Reinforced Concrete Buildings Part II: infilled structures, Journal of Earthquake Engineering, Vol.1, No.3, pp , ) Mostaghel, N., Hejazi, M. and Tanbakuchi, J.: Response of Sliding Structures to Harmonic Support Motion, Earthquake Engineering and Structural Dynamics, Vol.11, pp , ) Mostaghel, N. and Tanbakuchi, J.:Response of Sliding Structures to Earthquake Support Motion, Earthquake Engineering and Structural Dynamics, Vol.11, pp , ) Pujol, S. and Fick, D.: The Test of a Full-Scale Three Storey RC Structure with Masonry Infill Walls, Earthquake Engineering and Structural Dynamics, Vol.32, pp , ) Dolsek, M. and Fajfar, P.: The Effect of Masonry Infills on the Seismic Response of a Four-Storey Reinforced Concrete Frame- A Deterministic Assessment, Engineering Structures,Vol.3, pp , ) McCormick, J., Nagae, T., Ikenaga, M., Zhang, P., Katsuo, M. and Nakashima, M.: Investigation of the Sliding Behaviour between Steel and Mortar for Seismic Applications in Structures, Earthquake Engineering and Structural Dynamics, Vol.38, pp , ) Enokida, R., Nagae, T., Ikenaga, M., Inami, M. and Nakashima, M.: Application of Graphite Lubrication for Column Base in Free Standing Steel Structure, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.78, No.685, pp , (in Japanese) pp

8 SLIPPING BEHAVIOR OF BASE SHEAR CAPPING BUILDINGS FOR COLLAPSE PREVENTION AND REQUIRED MAXIMUM STRENGTH Ikumi HAMASHIMA *, Masahiro KURATA ** and Masayoshi NAKASHIMA *** * Grad. Student, Graduate School of Eng., Kyoto University ** Assoc. Prof., DPRI, Kyoto University, Ph.D. *** Prof., DPRI, Kyoto University, Ph.D. In regions prone to earthquake-induced ground shaking, buildings with insufficient seismic capacity may suffer severe damage and in the worst case collapse. Collapse of buildings lead to loss of many human lives. Thus, collapse prevention of the buildings is the first priority in realizing earthquake-resilient community in such regions. This study proposes the concept of a base shear capped building for collapse prevention as one of promising seismic retrofits. The structural system detaches the superstructure from the foundation in order to prevent collapse by letting the superstructure slide under huge earthquakes. When small earthquakes occur, the proposed structure does not slide against the foundation and behave like a fixed-base structure. When huge earthquakes occur, the structure starts to slide because the horizontal force which develops between the sliding base and foundation exceeds the maximum static friction force. The friction coefficient is one of key parameters in the sliding system. In this paper, graphite lubricant is used between steel and mortar, materials commonly used in building construction in order to obtain a target friction coefficient,. Previous numerical studies with a SDOF system revealed that the mass ratio, the weight of the superstructure over the total weight, was one of the ruling parameters. The objectives of this study are as follows: (1) Shaking table tests were conducted to evaluate the basic sliding behavior; and (2) The maximum base shear coefficient was estimated by numerical simulation when the proposed structure is subjected by pulse-type ground motions. In the experimental part, two types of specimens were designed: a basic specimen that simulates a SDOF system having a sliding system and a frame specimen that consisted of beams and columns. With those specimens, the stability of friction coefficient and the effects of the mass ratio and the variation of axial forces on the sliding behavior were investigated. Based on the test results, a simplified SDOF model featured with sliding behavior is developed, and the maximum base shear is estimated under pulse-type ground motions. Two types of input motions are used: an impulse motion and a set of SAC2 ground motions. Even if an existing building is brittle, it has some post-yielding ductility before collapse. To reflect this, additional numerical simulation is conducted using inelastic models and estimate the maximum required base shear coefficient when slight ductility, say two in ductility ratio, is permitted. The major findings are as follows: (1) Experimental studies verified the stability of friction coefficient between steel and mortar lubricated with graphite powder throughout all loading cases, and the dynamic friction coefficient is.16. (2) Even when the variation of axial force reached 5%, four column bases displaced equally, indicating that the effect of axial force variation on sliding behavior was minimal. (3) Numerical studies verified that there is an upper limit of the maximum base shear coefficient when the model is subjected to impulse motion, and the value of the upper limit is twice the friction coefficient. (4) For SAC2 ground motions, no obvious upper limit was present. However, even for earthquakes in level 2 (1 percent exceedance for 5 years), the maximum base shear coefficient remains at most 2.5 times the friction coefficient. (5) If slight ductility is permitted, the required maximum base shear coefficient can be reduced about twice the friction coefficient. (217 年 3 月 3 日原稿受理,217 年 8 月 2 日採用決定 ) 1776

JOURNAL OF EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION Vol. 31 No. 5 Oct /35 TU3521 P315.

31 5 2011 10 JOURNAL OF EARTHQUAKE ENGINEERING AND ENGINEERING VIBRATION Vol. 31 No. 5 Oct. 2011 1000-1301 2011 05-0075 - 09 510405 1 /35 TU3521 P315. 8 A Earthquake simulation shaking table test and analysis