INTERACTION OF RC FRAMES AND INFILL MASONRY WALLS UNDER SEISMIC LOADS

Transcription

1 Hazard Mitigation Of Civil Infrastructure INTERACTION OF RC FRAMES AND INFILL MASONRY WALLS UNDER SEISMIC LOADS Luis Omar Rubio The University of Texas at Arlington

2 Earthquakes Hazard

3 Hazard Mitigation Use & understand the interaction between Reinforced Concrete (RC) frames and masonry infill walls Masonry walls may change the stiffness and consequently, the period of the structure It is necessary to take into account their effect to correctly design the structure Obtain the interaction through Pushover Analysis

4 Background: RC Frames Many countries, like Spain, use abundant of masonry infill walls in their buildings RC frame building with masonry walls are generally taken as an aesthetic component only due to calculation complications Many studies have shown that masonry infill walls help with increasing the structure s stiffness, but also Complications when it is partially filled or with different size openings: soft story, short column Further research is needed to fully understand the interaction between RC frames and infill walls

5 Introduction Dr. Pallarés Rubio is currently researching the interaction between RC frames and infill masonry walls Both theoretical and experimental models are being used to analyze the ultimate capacity and possible failure modes o Theoretical: Non-linear Static Pushover Analysis through SAP2000 o Experimental: 5mX3m frames subjected to a constant horizontal load

6 Introduction My Part in the Project o Working only with theoretical models o Creating and running frame models on SAP2000 o Data Analysis

7

8 My Objectives Model concrete frame Define sections Find stiffness of the different types of frames o Without equivalent strut o With equivalent strut Compare results

9 Background: Pushover Analysis An analysis in which assesses seismic vulnerability of existing structures A static non-linear analysis under permanent vertical loads and gradually increasing lateral loads until a certain displacement or failure A method to observe the successive damage states of a building A plot of total base shear versus top displacement in a structure is obtained (would indicate any premature failure or weakness)

10 2-D Concrete Frame Model 3 different types of beams 2 different types of columns Pinned end connections

11 Cross- Sections Beam Type 1 Type 2 Type 3 Column Type 1 Type 2

12 SAP2000 & Challenges A civil engineering based software which analyzes buildings or any other structural system Defining the materials o Strut to be equal as masonry infill properties Modeling the frame and members o Strut to act as a masonry infill wall The analysis o Having to go find the results

13 The Procedure

14 The Procedure

15 Analysis Model information Software plots the base shear vs displacement Modal analysis is obtained: T (period) Show weakest/failure point through T (period) and data tables of capacity spectrum Concrete Frame-Stiffness with and without Masonry Infill Wall Hinges Analysis Beam Column Modal Control Displacement Load Case Relative Distance Load Case Relative Distance For node 15 (m) 1.1 DEAD PUSH RUN DEAD PUSH RUN 0.3

16 Analysis Force Deformation Curve Method for Equivalent Strut Stiffness

17 Equivalent Strut for modeling Masonry Infill Estimating the width of the strut using Paulay & Priestley formula approach Estimating the relative stiffness of the masonry infill wall using Benjamin formula approach Estimating shear modulus of the masonry infill wall

18 Equivalent Strut for modeling Masonry Infill Assumptions and Parameters of Masonry Infill o Cross-section area of gantry, A c : 0.09 m 2 o Modulus of Elasticity of concrete, E c : MPA o Moment of Inertia of column, I c : x 10-4 in 4 o Poisson ratio of masonry infill, v: 0.25 o Young s Modulus of Elasticity of masonry infill, Em: 2500 Mpa o Shear Modulus of masonry infill, G m : 1000 Mpa o Thickness of masonry infill wall, t: 0.1 m Width of Strut and Stiffness of Masonry Infill Wall o w = m o K = KN/m

19

20 Results 2-D RC Model Frame without Masonry Infill Wall

21 Results 2-D RC Model Frame with Masonry Infill Wall

22 Base Reaction Force, KN Results Resultant Base Shear vs Monitored Displacement : Without Masonry Infill Wall 1.2: With Masonry Infill Wall Displacement, m *The stiffness is the slope of the linear part of the curve starting at zero

23 Comparison Without Masonry Infill wall T = seconds K = KN/m With Masonry Infill Wall T = seconds K = KN/m

24 Conclusion Including the masonry infill wall dramatically increased the stiffness of the structure Further research is still needed to fully understand the interaction of RC frames with masonry infill walls Special thanks to Dr. Pallarés Rubio and the rest of the UPV staff for everything they have done for me and for making this internship such a wonderful experience

25 References Pradhan, Prachand Man. "Equivalent Strut Width for Partial Infilled Frames." JCE Journal of Civil Engineering Research 2.5 (2012): Web.., Mohammad H. Jinya, and V. R. Patel. "Analysis Of RC Frame With And Without Masonry Infill Wall With Different Stiffness With Outer Central Opening." International Journal of Research in Engineering and Technology IJRET (2014): Web. "Structural Software for Analysis and Design SAP2000." Computers and Structures, Inc. N.p., n.d. Web. 13 July < ComputersNstructures. "SAP Static Pushover Analysis: Watch & Learn." YouTube. YouTube, 12 Aug Web. 13 July < CARLOSCORDOVA1. "ANALISIS ESTATICO NO LINEAL "PUSHOVER" POR EL M.Sc. ING. CARLOS CORDOVA." YouTube. YouTube, 03 Jan Web. 13 July < UVO14&list=PL8q8YdTZlrVHNBKWEl_vIgLe7wEB_anu3>. Revert, Andres Belda.. Estudio Experimental de la Influencia del Relleno de Mamposteria Sobre Porticos de Hormigon Armado Frente a Acciones Horizontales. Universitaria Politecnica de Valencia(July 2014). Freeman, Sigmund A. Review of the Development of the Capacity Spectrum Methodd. ISET Journal of Earthquake Technology, Paper No. 438, Vol. 41, No. 1, March 2004, pp Bharali, Ritukesh., Deka, Bhargob., & Pathak, Jayanta. Retrofitting Open Ground Storey Building with Masonry Walls in Guwahati City. Indian Institute of Technology, Roorkee (2014). Leslie, Rahul. The Pushover Analysis, Explained in its Simplicity. Proceedings of 2 nd National Conference RACE 13 at SAINTGITS College of Engineering, Kottayam (Unknown). Abdelkareem, K. H., Sayed, F. K. Abdel., Ahmed, M. H., & AL-Mekhlafy, N. Equivalent Strut Width for Modeling R.C. Infilled Frames. Civil Engineering Department, Faculty of Engineering, Assiut University (2013). Unknown. Non-linear Static Push-over Analysis. n.p., n.d., Unknown. 7. Masonry. n.p, n.d., <

26 Questions???

27 THANK YOU!