カテゴリー Ⅱ 日本建築学会構造系論文集第 83 巻第 744 号, ,2018 年 2 月 J. Struct. Constr. Eng., AIJ, Vol. 83 No. 744, , Feb., 2018 DOI

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1 カテゴリー Ⅱ 日本建築学会構造系論文集第 83 巻第 744 号, ,218 年 2 月 J. Struct. Constr. Eng., AIJ, Vol. 83 No. 744, , Feb., 218 DOI 片面加熱および偏心圧縮を受ける鉄筋コンクリート造壁柱の火災時挙動鉄筋コンクリート造長柱の耐火性能に関する研究その 3 BEHAVIOR OF RC WALL COLUMNS SUBJECTED TO ONE SIDE HEATING AND ECCENTRIC AXIAL LOAD IN FIRE Study on fire resistance of slender RC columns Part 3 加藤雅樹 *1, 道越真太郎 *2, 馬場重彰 *2 *3, 坂田弘安 Masaki KATO, Shintaro MICHIKOSHI, Shigeaki BABA and Hiroyasu SAKATA This study shows fire resistance of RC wall columns subjected to one side heating and decentering axial load. Fire-resistance tests were conducted for the RC wall columns, and we consequently obtained the fire-resistance time, deformation behavior and failure mode. In addition, thermal stress analyses in consideration of geometrical nonlinearity were conducted in order to evaluate the experimental results. Comparing the experimental and analytical results, the proposed analytical method offers a good approximation of behavior of RC wall columns in fire. Keywords : Buckling, Non-uniform heating, Additional moment, Fire resistance test, Thermal stress analysis 1. ( RC ) RC ( ) RC 1) RC 2) RC RC ( RC ) 3) RC 4) RC RC RC RC RC RC 5) RC RC 1/1 RC MACLEAN 6) RC 2 BUCHANAN 7) RC *1 *2 *3 大成建設技術センター修士 ( 工学 ) 大成建設技術センター博士 ( 工学 ) 東京工業大学環境社会理工学院建築学系教授工博 Technology Center, Taisei Corp., M.Eng. Technology Center, Taisei Corp., Dr.Eng. Prof., Dept. of Arch. and Build. Eng., Tokyo Institute of Technology, Dr.Eng. 343

2 RC RC RC RC RC RC RC Table1 Fig. 1 5 mm mm mm ( 4 ) 1 ( 1 ) mm ( ) 25mm 42mm( ) Table2 Table3 Table % RC 8) ( Table1 Specimens Cross Column Axial force Eccentric Heating side Name -section height ratio distance of cross-section size [mm] [mm] N / ( B A) * [mm] H4-3- all circumferences.3 H H1-4-. one side H H * N : Axial force, B : Compressive strength of concrete, A : Cross-section area 75 H4-3-, H1-3-, H1-4- (Eccentric distance : mm) (a) Elevation Unit : [mm] H1-3-25, H1-3-42, (Eccentric distance : 25,42mm) PL-12 PL-12 Main rebar 1-D19(SD49) (pg=1.91%) Inner supplementary tie D1@3(SD295A) Shear reinforcement -D1@1(SD295A) (pw=.32%) (b) Cross-section of columns Shear reinforcement -D1@6(SD295A) (pw=.95%) PL Fig. 1 Reinforcement arrangement Main rebar 2+2-D22(SD39) (pg=1.18%) (c) Cross-section of beams Table2 Mix proportioning of concrete Ordinary portland cement : Slag and Gypsum Binder : B : Silica fume = 7 2 1(Density : 2.99g/cm 3 ) Natural sand from Kimitsu (Density in saturated Fine aggregate : S surface-dry condition : 2.62g/cm 3 ) Crushed stone from Otsuki Coarse (Andesite, Max. size : 2mm, Density in saturated aggregate : G surface-dry condition : 2.62g/cm 3 ) Superplastizicer High-performance water reducing agent : SP (Polycarboxylic acid ethers) Polypropylene fiber Thermoplastic (Diameter :.48mm, Length : 2mm, fiber : PP Density :.91g/cm 3 ) Air Unit quantity W/B SP PP content W B S G [%] [%] [kg/m 3 ] [kg/m 3 ] Table3 Mechanical properties of use material at room temperature (a) Concrete Compressive strength B Young's modulus E c Poisson's ratio [N/mm 2 ] [ 1 4 N/mm 2 ] [ - ] (b) Rebar Yield point Young's Tensile Breaking Reinforcing y modulus E s strength t elongation bars [N/mm 2 ] [ 1 5 N/mm 2 ] [N/mm 2 ] [%] D19(SD49) D22(SD39) D1(SD295A)

3 ) 1 Displacement transducer PL-12 Insulation Burner Specimen Insulation Displacement transducer Stub 255 (a) Heating side of cross-section : all circumferences Eccentric distance Burner PL-12 Insulation Specimen PL-7 Spherical bearing (r=23) 367 (Heating range) (Column height) PL-25 Spherical bearing (r=23) 1 37 (Heating range) (Column height) : Position of strain gauges : Position of displacement transducer (b) Heating side of cross-section : one side (example of eccentric distance : 42mm) A 42 A' Fig. 2 Test setup Non-heating side (Room temperature) Heating side 3 3 Heat insulation A-A' cross-section Unit : [mm] 9) 1) RC RC 1) 1).2 3 D19(SD49) JIS G 567-6,,,, 1 5 JIS G 567 1%.3%/ 7.5%/ RC Fig. 2 Fig. 2(a) 4 Fig. 2(b) 1 7mm ISO834 Table3 Fig. 2(b) 1 42mm ( ) 1 mm mm 1 Fig. 2(b) ce-m ce-s co-s co-m From top, co-,15,,8 (a) Heating side of cross-section : all circumferences From left, ce-,15,,8,125 : concrete : Rebar (Heating side) From left, ce-,15,,8,125, ce-hm ce-hs 125 (Non-heating side) ce-ns ce-nm (b) Heating side of cross-section : one side Unit : [mm] Fig. 3 Position of temperature measurement 345

4 Fig RC ) Fig. 4 Fig ) SD49 Table4 Fig. 5 Fig RC Fig. 6 4 H H1-3- H Fig. 6 1 ( ) H Fig. 7 mm H H H H H (H4-3- H1-3-) 4 (H1-3- H H1-3-42) 4 26mm 1 4mm 1 Fig. 8 mm 1 15 Stress [N/mm 2 ] ([deg C] : failure during temperature rise) Experiment Analysis model 1 Room 12 temperature 1 [deg C] [deg C] 8 6 [deg C] 2 7[deg C] Stress-dependent strain [ ] Free thermal strain [ ] y = -4.62E-1x E-7x E-4x E-1x E+x + 4.9E+1 ( x ) Experiment Analysis model 1 (a) Stress stress-dependent (b) Free thermal strain strain relationships temperature relationship 1 Axial force ratio :.1 Transient strain / Axial force ratio [ /(-)] Axial force ratio :.3 Axial force ratio :.2 K = 2.5 K = 4.9 Analysis model - Free thermal strain [ ] (c) Transient strain / axial force ratio free thermal strain relationships Fig. 4 Result of concrete compressive test in high temperature 8) Stress [N/mm 2 ] Table4 Result of reinforcing bars (SD49) tensile test in high temperature Temperature Yield point * T ensile Breaking strength elongation [deg C] [N/mm 2 ] [N/mm 2 ] [%] *.2% offset yield strength Experiment Analysis model Room temperature [deg C] [deg C] Stress-dependent strain [ ] (a) RT ~ deg C Stress [N/mm 2 ] 3 1 [deg C] [deg C] 1 [deg C] Stress-dependent strain [ ] (b) ~ 1deg C Fig. 5 Stress - strain relationships of reinforcing bar in high temperature 346

5 Vertical displacement at top of the columns [mm] Experiment Pre-analysis result Heating Time [min.] Heating time [min.] (a) H Heating Time [min.] Experiment Pre-analysis result Heating time [min.] (b) H1-3- Fig. 6 Temperature of cross-section (expansion) Experiment Analysis result H4-3- H1-4- H (contraction) H1-3- H co-s co-m ce-m ce-s From top, co- co-15 co- co-8 From left, ce- ce-15 ce- ce-8 ce-125 ce-nm ce-ns ce-hm ce-hs From left, ce- ce-15 ce- ce-8 ce-125 ce Heating time [min.] Fig. 7 Vertical displacement at top of the columns (Legend) Name (Fire-resistance time) Experiment Analysis H1-3- 3min. 12min 18min. 215min. 214min. H1-4- 3min. 6min. 9min 126min. 123min. H min. 6min. 9min 144min. 122min. H min. 6min. 75min. 93min. 82min. Experiment Starin at compressive strength Analysis result H.S. : Heating side, N-H.S. : Non-heating side Comp. : Compression, Tens. : Tension (H.S.) (N-H.S) displacment [mm] 1 1 (a) H (H.S.) (N-H.S) displacment [mm] - (Comp.) (Tens.) Surface strain on N-H.S [ ] 1 (b) H (H.S.) (N-H.S) displacment [mm] - (Comp.) (Tens.) Surface strain on N-H.S [ ] 1 (c) H (H.S.) (N-H.S) displacment [mm] - (Comp.) (Tens.) Surface strain on N-H.S [ ] 1 (d) H (Comp.) (Tens.) Surface strain on N-H.S [ ] Fig. 8 Distribution of horizontal displacement and surface strain 347

Reaction force Rigid beam (Heating side) Predefined axial force (Non-heating side) Decrease in reaction force Horizontal deflection

in fixed end moment (a) At room (b) Initial heating (c) Failure temperature Fig.

Eccentric distance (Heating side) (Non-heating side) 21 16.9 34 53.

7*3 Centric Eccentric elements) loading loading Unit : [mm] (a) Elevation (b) Cross-section Fig.

6 Reaction force Rigid beam (Heating side) Predefined axial force (Non-heating side) Decrease in reaction force Horizontal deflection Decrease in moment Distribution of moment at room temperature Increase in reaction force Increase in moment Horizontal deflection Change in fixed end moment (a) At room (b) Initial heating (c) Failure temperature Fig. 9 Distribution of moment (example of eccentric loading) Strain gauge lead Z Y X Predefined axial load h= (5*9 elements) Rigid beam Eccentric distance (Heating side) (Non-heating side) Total : 196 elements Concrete : 184 elements Main rebar : 12 elements (17.*2 elements) (17.7*3 Centric Eccentric elements) loading loading Unit : [mm] (a) Elevation (b) Cross-section Fig. 1 Analysis model Photo1 4 H4-3- Photo1 1 H (28.8*2 elements) Y X Heating side (a) H4-3- Nonheating side Heating side Insulation side (b) H Photo1 Specimens after tests Enlargement at bottom of column 5 1 Fig. 9(a) Fig. 9(b) Fig. 9(c) ),2) FEM ABAQUS 2 12) 2) Fig /4 2 mm 9 1 5mm Z 348

7 ( ) ( ) 1) Fig. 2 mm mm 13) Z ),2) 14) kg/m 3 5.% W/(m 2 K) 1 5.8W/(m 2 K) ISO popovics 15) (1) Table5(a) Fig. 4(a) = n T T T n T -1+( / T ) nt (1) T T T T n T T Fig. 4(b) 5 Table5 Temperature-dependent properties (a) Concrete 2 7 and over Compressive strength T [N/mm 2 ] Young's modulus E T [ 1 4 N/mm 2 ] Strain at compressive strength T [ ] Shape-dependent coefficient n T Young's modulus E T [ 1 5 N/mm 2 ] * k (b) Main rebar coefficient defined [N/mm 2 ] by plastic strain * k * Same value in 1 [deg C] or more Anderberg (2) 16) K Fig. 4(c) d tr = K B (-d th ) d tr K B d th 17) (3) 12) Table5(b) Fig. 5 k = e + p = + E T k e p E T T k, k T 3.2 Fig. 1(b) Fig. 1(b) Fig. 6 Fig. 3 mm mm 1mm (2) (3) 349

8 Axial force ratio H1-4- (Experiment) Legend (analysis) Heating side of cross-section all circumferences Eccentric distance [mm] one side H1-3- (Experiment).2 H H H4-3- (Experiment) (Experiment) (Experiment) Fire-resistance time [min.] Fig. 11 Axial force ratio Fire-resistance time relationships Fig. 6 H4-3- ce-,ce-15 1 H1-3- ce-,ce Fig. 7 Fig. 8 (H H1-3-42) Fig. 1(b) Fig. 8 (3334 ) Fig ) (Fig. 11 ) 4 1 (Fig. 11 ) RC 12N/mm 2 mm mm RC RC 1),2) RC RC 1) Masaki Kato, Shintaro Michikoshi, Shigeaki Baba, Kazumasa Imai and Satoshi Watanabe: Buckling Strength of Slender RC Columns Subjected to Centric Axial Load in Fire Study on fire resistance of slender RC columns Part 1, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.8, No.78, pp , (in Japanese),,,, :,, 78, pp , ) Masaki Kato, Shintaro Michikoshi, Shigeaki Baba and Hiroyasu Sakata: Behavior of Slender RC Columns with Initial Deformation in Fire Study on fire resistance of slender RC columns Part 2, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.82, No.736, pp , (in Japanese),,, :,, 736, pp , ) Tsubasa Tani, Ryota Maseki, Hiroshi Hibino and Izuru Takewaki: Durability of Laminated Rubber as Rotary Bearing Development of vibration controlled high-rise RC building with low stiffness at lower stories using shear-wall and oil-dampers part 1, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.82, No.733, pp.395-3, (in Japanese),,, : RC 1, 733, pp.395-3, ) Keijiro Yamakawa, Tomoaki Sugiyama, Yasuhiro Nishikawa, Hiroyuki Narihara and Shoji Katsuta: Structural performance of reinforced concrete eccentric beam-column joints Part1 Outline of the test and failure mode, Summaries of technical papers of Annual Meeting, Architectural Institute of Japan, C-2, pp , 21.7 (in Japanese),,,, : RC 1,, C-2, pp , ) Takeshi Morita, Masuhiro Beppu and Makoto Suzuki: An Experimental Study on Structural Fire Behavior of Reinforced Concrete Wall after 35

9 High Velocity Impact of Hard Projectile, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.8, No.78, pp , (in Japanese),, :,, 78, pp , ) JAMIE MACLEAN, VADIMS GOREMIKINS, LUKE BISBY and TIM STRATFORD: Effects of Localised or Non-Uniform Heating on Reinforced Concrete Columns, 9th International Conference on Structures in Fire, USA, pp.12-19, ) ANDREW H. BUCHANAN, V. RAO MUNUKUTLA: Fire Resistance of Load-Bearing Reinforced Concrete Walls, Proceedings of the 3 rd International Symposium on Fire Safety Science, pp , ) Masaki Kato, Shintaro Michikoshi, Shigeaki Baba and Hiroyasu Sakata: Compressive Tests of 11N/mm 2 Class High Strength Concrete in High Temperature, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Fire Safety, pp , (in Japanese),,, : 11N/mm 2,,, pp , ) Masatosi Tokoyoda and Heisuke Hirashima: Compression Tests of Concrete Heated up to 7 with Restraining Force in High Temperature and Room Temperature Condition, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, A-2, pp.5-6, (in Japanese), 7,, A-2, pp.5-6, 6.9 1) Masaki Kato, Shintaro Michikoshi, Shigeaki Baba, Shusuke Kuroiwa and Hiroshi Jinnai: Compressive Tests of 1N/mm 2 High Strength Concrete in High Temperature and after Heating Conditions, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, A-2, pp.13-14, (in Japanese),,,, : 1N/mm 2,, A-2, pp.13-14, ) Heisuke Yamashita, Toru Yoshida, Daiki Shishikura, Masatoshi Tokoyoda and Takeo Hirashima: Influence of Curing Condition and Water Cement Ratio on Load-Induced Thermal Strain of Concrete Influence of water content on properties of concrete in high temperatures Part2, Journal of Structural and Construction Engineering (Transactions of AIJ), Vol.81, No.727, pp , (in Japanese),,,, : ( ),, 727, pp , ) Hideki Uesugi and Hiroshi Koike: Thermal Stress of Steel Structures of Tall Buildings in Fire Part1 Computer analysis method of tall structures exposed to compartment fire, Journal of Structural and Construction Engineering (Transactions of AIJ), No.381, pp.73-8, (in Japanese), : ( 1),, 381, pp.73-8, ) Masaki Kato, Shintaro Michikoshi and Shigeaki Baba: Fundamental Study on Buckling of Slender RC Columns with Heated and Non-Heated Areas in Fire, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, Fire Safety, pp.63-64, (in Japanese),, : RC,,, pp.63-64, ) Shintaro Michikoshi and Yutaka Kobayashi: Mechanical Properties of High Strength Concrete at High Temperatures, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, A-2, pp.79-8, (in Japanese), :,, A-2, pp.79-8, ) Sandor Popovics: A Numerical Approach to the Complete Stress - Strain Curve of Concrete, CEMENT and CONCRETE RESEARCH, Vol.3, pp , ) Yngve Anderberg and Sven Thelandersson: Stress and Deformation Characteristics of Concrete at High Temperature, Lund Institute of Technology, Bulletin No.54, Lund, Sweden ) Kakuhiro Nagao, Hiroaki Eto, Hironori Niwa and Hideki Uesugi: The Results of Elevated Temperature Tensile Tests of Reinforcing Bars, Summaries of Technical Papers of Annual Meeting, Architectural Institute of Japan, A-2, pp.75-76, 21.9 (in Japanese),,, :, A-2, pp ,

10 BEHAVIOR OF RC WALL COLUMNS SUBJECTED TO ONE SIDE HEATING AND ECCENTRIC AXIAL LOAD IN FIRE Study on fire resistance of slender RC columns Part 3 Masaki KATO *1, Shintaro MICHIKOSHI *2, Shigeaki BABA *2 and Hiroyasu SAKATA *3 *1 Technology Center, Taisei Corp., M.Eng. *2 Technology Center, Taisei Corp., Dr.Eng. *3 Prof., Dept. of Arch. and Build. Eng., Tokyo Institute of Technology, Dr.Eng. Reinforced concrete columns formed with high-strength concrete have been developed with a smaller cross section than conventional short columns as axial load carrying members. Known as slender columns, they can enlarge building space and provide good visibility in architectural space. RC wall columns whose shape of cross-section are flat and the smallest diameter are small on an equality with slender RC columns are used as earthquake resisting elements for enhancing horizontal stiffness of structural frame. They have been also developed as quake-absorbing system and vibration control system known as damage-controlled system. These RC wall columns belong in the slender RC columns defined by authors in case the ratio of column height to cross sectional smallest diameter is large. RC wall columns are possibly heated with one side when RC walls are used as outer wall. In these one side heating situations, RC wall columns are displaced toward a horizontal direction due to non-uniform thermal degradation of the cross-section. And furthermore, axial load generates additional moment. Bending stiffness decreases considerably due to thermal degradation of the heated surface in fire. It is anticipated that RC wall columns subjected to one side heating would fail earlier than ones subjected to all circumferences heating because of this additional moment. Moreover, it is similarly anticipated that additional moment generated by an eccentric joint of beams would lower the fire-resistance performance of RC wall columns. This paper presents the results from an experimental and analytical studies of RC wall columns subjected to one side heating and decentering axial load in fire and leads to a discussion of fire performance which includes deformation behavior, failure mode and fire resistance time. All specimens consist of concrete with a compressive strength of approximately 12N/mm 2 and have rectangular cross-section with sides mm and mm in length and mm in height. Comparing the experimental and analytical results, the analysis method using a fiber model based on the mechanical properties of the materials in high temperature offers a good approximation of deformation behavior, failure mode and fire resistance time. In addition, the results confirm that the centrally loaded specimens subjected to one side heating fail earlier than ones subjected to all circumferences heating under conditions that axial load ratio is about.3 or over. (217 年 9 月 1 日原稿受理,217 年 1 月 3 日採用決定 ) 352

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