Seismic Performance of Seismic Performance of Reinforced Concrete - PowerPoint PPT Presentation

Seismic Performance of Seismic Performance of Reinforced Concrete Columns Reinforced Concrete Columns Under Biaxial Excitation Under Biaxial Excitation Tiffany McCarthy Dept. of Civil & Environmental Engineering University of Houston NSF REU Program August 2007

Contents Contents  Introduction Introduction  Objectives and Scope Objectives and Scope  Experiment Experiment  Results Results  Analysis Analysis  Applications Applications  Closing Statement Closing Statement  Questions? Questions?

Introduction Introduction  Seismic = Earthquake - Related Seismic = Earthquake - Related  Reinforced = Strengthened/Supported Reinforced = Strengthened/Supported  Biaxial = 2 Axes Biaxial = 2 Axes  Excitation = Acceleration Excitation = Acceleration  1999 Taiwan Earthquake 1999 Taiwan Earthquake

1999 Taiwan Earthquake 1999 Taiwan Earthquake

Tungtow Bridge Tungtow Bridge

Tungtow Close-Up Tungtow Close-Up

Taichung Building Taichung Building

Changhwa Building Changhwa Building

Objectives and Scope Objectives and Scope  Subject to biaxial loads Subject to biaxial loads – Test using more realistic conditions Test using more realistic conditions  Determine Determine – Effect of orientation Effect of orientation – Effect of shear reinforcement ratio Effect of shear reinforcement ratio

Experimental Program Experimental Program

Steel Reinforcement Steel Reinforcement

Formwork Formwork

Concrete Column Concrete Column

Shake Table Shake Table

Results Results  Cracking and Yielding Cracking and Yielding  Failure Modes Failure Modes  Ultimate Forces Ultimate Forces  Steel Yielding Steel Yielding  Energy Dissipation Energy Dissipation  Hysteretic Response Hysteretic Response

SH1 and SH4 SH1 and SH4

SH2 and SH5 SH2 and SH5

SH3 and SH6 SH3 and SH6

Force v. Displacement Force v. Displacement (SH1 [left] and SH5 [right]) (SH1 [left] and SH5 [right]) SH1 @ 1200gal SH5 @ 1600 gal 2.50E+05 2.50E+05 2.00E+05 2.00E+05 1.50E+05 1.50E+05 1.00E+05 1.00E+05 5.00E+04 Force 5.00E+04 Force 0.00E+00 0.00E+00 -3.00E+0 -2.00E+0 -1.00E+0 -5.00E+04 0.00E+00 1.00E+01 2.00E+01 3.00E+01 -2.00E -1.50E -1.00E -5.00E 0.00E+ 5.00E+ 1.00E+ 1.50E+ 2.00E+ -5.00E+04 1 1 -1.00E+05 1 +01 +01 +01 +00 00 00 01 01 01 -1.00E+05 -1.50E+05 -1.50E+05 -2.00E+05 -2.00E+05 -2.50E+05 Displacement Displacement

Experimental Analysis Experimental Analysis  Symmetry significant to Symmetry significant to – Stiffness Stiffness – Strength Strength – Deformation Deformation  Lower Energy Dissipation Than Uniaxial Lower Energy Dissipation Than Uniaxial  Cracking and Yielding Cracking and Yielding   Stiffness decr. Stiffness decr.  Stirrup Spacing affects energy dissipation Stirrup Spacing affects energy dissipation at high excitation at high excitation

Applications Applications  More Reinforcements=More Resistant More Reinforcements=More Resistant  Orientation to Force is Key Orientation to Force is Key  Symmetry Matters Symmetry Matters  Reduce Spalling Reduce Spalling

Statement Closing Statement Closing  Reinforcement and Biaxial Loads are Reinforcement and Biaxial Loads are significant topics to consider when significant topics to consider when developing better guidelines for concrete developing better guidelines for concrete structures. structures.

Questions? Questions?