Behaviour of reinforced concrete frame with in fill walls under seismic loads using etabs
4 likes1,134 views
This document summarizes a study on the behavior of reinforced concrete frames with masonry infill walls under seismic loads. Five models of a 10-story reinforced concrete building were analyzed using ETABS software: a bare frame, a fully infilled frame, and frames with different infill wall configurations. The results show that infill walls increase the lateral stiffness and strength of the frame, reducing displacements and member forces. However, openings in infill walls decrease stiffness. A higher Young's modulus for the infill material further increases stiffness. The analysis provides insights into how the structural response is affected by infill wall properties.
![Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14)
30 – 31, December 2014, Ernakulam, India
187
REFERENCES
[1] Prof.R.Ravi, Prof.Dr.C.Manoharan, Experimental Studies on Characterising of seismic Performance of
Reinforced Concrete Frames, IOSR Journal of Mechanical and Civil Engineering (IOSRJMCE) ISSN: Issue 1
2278-1684 Vol.2, July-August 2012, pp 08-24.
[2] S.Niruba, K.V.Boobalakrishnan, K.M.Gopalakrishnan, Analysis of Masonry Infill In A Multi-Storied Building
International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, Issue 3(March
2014), (Print) 2319-1821 Vol. 3, 2012, pp.26-31.
[3] Kashif Mahmud1*, Md. Rashadul Islam and Md. Al-Amin, Study the Reinforced Concrete Frame with Brick
Masonry Infill due to Lateral Loads, International Journal of Civil & Environmental Engineering IJCEE-IJENS
[4] Haroon Rasheed Tamboli and Umesh.N.Karadi, Seismic Analysis of RC Frame Structure with and without
Masonry Infill Walls. Indian Journal Of Natural Sciences: Vol.3 / Issue 14/, 2012.
[5] IS 1893:2002 Criteria For Earthquake Resistant Design Of Structures, Part 1 General Provision and Buildings.
[6] IS 4326: 1993 Earthquake Resistant Design And Construction Of Buildings, Code Of Practice.
[7] Imran.I and L.Aryanto, Behaviour of reinforced concrete frames in filled with lightweight materials under
seismic loads, Structural Engineering Research Journal, Indonesia, vol.11, Title no.2, 2009, pp 69-77.
[8] Mehmet Baran and Tugrul Tankut, 2011Experimental study on seismic strengthening of reinforced concrete
frames by precast concrete panels under seismic loading, ACI Structural Journal, vol.108, Title no.23, pp 227.
[9] Pankaj Agarwal and Manish Shrikhande, 2010. Earthquake Resistant Design of Structures, Eight Edition, PHI
Learning Private Ltd, New Delhi.
[10] Rehan A.Khan, Seismic Reliability analysis of RCC building frame, International Journal of Earth Sciences and
Engineering ,Title no. 0974, 2006, pp – 13.
[11] Amin Ali Ahfid, Dr. R.K.Pandey, Er C S Mishra and Dr. Ajeet Kumar Rai, “Dynamic and Pushover Analysis of
Three Dimensional Models of Buildings for Rigid Floor Diaphragm Idealization using ETAB”, International
Journal of Civil Engineering & Technology (IJCIET), Volume 5, Issue 3, 2014, pp. 92 - 99, ISSN Print:
0976 – 6308, ISSN Online: 0976 – 6316.](https://image.slidesharecdn.com/behaviourofreinforcedconcreteframewithinfillwallsunderseismicloadsusingetabs-141216075533-conversion-gate02/85/Behaviour-of-reinforced-concrete-frame-with-in-fill-walls-under-seismic-loads-using-etabs-7-320.jpg)
Behaviour of reinforced concrete frame with in fill walls under seismic loads using etabs
- 1. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 181 BEHAVIOUR OF REINFORCED CONCRETE FRAME WITH IN-FILL WALLS UNDER SEISMIC LOADS USING ETABS Shaharban P.S1 , Manju P.M2 1 (M.Tech Computer Aided Structural Engineering, Sree Narayana Gurukulam College of Engineering, Kadayiruppu, Eranakulam, Kerala, India 2 (Asst. Prof, Dept of Civil Engineering, Sree Narayana Gurukulam College of Engineering, Kadayiruppu, Eranakulam, Kerala, India ABSTRACT Reinforced concrete framed buildings with in-fills are usually analyzed as bare frame, without considering the strength and stiffness contributions of the in-fills. However during wind and earthquake these infill walls contribute some response of the structure. Masonry Brick infill walls have been used in Reinforced concrete Frame structures as interior and exterior partition walls. Since they are usually considered as nonstructural elements their interaction with the bonding frame is ignored in the design. Infill substantially alters the behavior of the building subjected to lateral loads such as wind and earth quake forces. However when subjected to a strong lateral loads, infill panels tends to interact with bonding frame and may induce a load resistance mechanism that is not accounted for the design. To study the performance of masonry- in filled R.C frames under Brick infill wall condition, analytical investigations have been conducted. The objective of this study is to investigate the behavior of Brick masonry in-fill R.C Frames under cyclic lateral loading. The Analysis has been done using Etabs software. In this project report five different type of models has been analyzed. A 10 storey building with and without Brick infill was tested under siesmic load for case one. A 10 storey building with 4 different infill conditions are analysed. Keywords: Displacement, Etabs, Infill walls, Siesmic, Stiffness. 1. INTRODUCTION Reinforced concrete (RC) frame buildings with masonry infill walls have been widely constructed for commercial, industrial and multi storey residential uses in seismic regions. Masonry infill typically consists of bricks or concrete blocks constructed between beams and columns of a reinforced concrete frame. The masonry infill panels are generally not considered in the design process and treated as architectural (non-structural) components. Nevertheless, the presence of masonry infill walls has a significant impact on the seismic response of a reinforced concrete frame building, increasing structural strength and stiffness (relative to a bare frame). Properly designed infill can increase the overall strength, lateral resistance and energy dissipation of the structure. An infill wall reduces the lateral deflections and bending moments in the frame, thereby decreasing the probability of collapse. Hence, accounting for the infill in the analysis and design leads to slender frame members, reducing the overall cost of the structural system. The total base shear experienced by a building during an earthquake is dependent on its time period. The seismic force distribution is dependent on the stiffness and mass of the building along the height. The structural contribution of infill wall results into stiffer structure thereby reducing the storey drifts (lateral INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 5, Issue 12, December (2014), pp. 181-187 © IAEME: www.iaeme.com/Ijciet.asp Journal Impact Factor (2014): 7.9290 (Calculated by GISI) www.jifactor.com IJCIET ©IAEME
- 2. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 182 displacement at floor level). This improved performance makes the structural design more realistic to consider infill walls as a structural element in the earthquake resistant design of structures. A panel constructed from masonry, usually built in between the columns and beams of the structural frame of a building. Infill walls are used in framed building construction to create the building facade or envelope (external infill walls) and to sub-divide the internal space of the building (internal infill walls). Traditionally external infill walls have been of masonry construction and internal infill walls have been of either masonry or timber stud with plasterboard. More recently light steel sections have also been used to form both internal and external infill walls. Infill walls do not need to use the same structural material as the primary building frame. For example, light steel infill walls may be used in a concrete framed building. Using lighter weight infill walls has the obvious advantage of reducing the load on the structure. Masonry is the building of structures from which individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, travertine, limestone, cast stone, concrete block, glass block, stucco, and tile. Masonry is generally a highly durable form of construction. Various advantages have been acquired on analyzing the structures with infill, they are, 1. The use of materials such as bricks and stones can increase the thermal mass of a building. 2. Most types of masonry typically will not require painting and so can provide a structure with reduced life-cycle costs. 3. Masonry is very heat resistant and thus provides good fire protection. 4. Masonry walls are more resistant to projectiles, such as debris from hurricanes or tornados. Here also arise some of the disadvantages like, 1. Extreme weather causes degradation of masonry wall surfaces due to frost damage. This type of damage is common with certain types of brick, though rare with concrete blocks. 2. Masonry tends to be heavy and must be built upon a strong foundation, such as reinforced concrete, to avoid setting and cracking. 3. Save for concrete, masonry construction does not lend itself well to mechanization, and requires more skilled labour than stick-framing. In Euro code 6, six types of masonry units are defined: clay units, calcium silicate units, aggregate concrete units, autoclaved aerated concrete units, manufactured stone units and dimensioned natural stone units complied with the relevant European standards EN 771-1 to 6. However, brickwork can be combined from many of the following components: adobe, ashlars, blocks, bricks, bitumen, chalk, cement, lime and mortar. Depending on which materials are used, and how they are located, reinforced masonry (RM) walls can be divided into the following classes: confined masonry, reinforced cavity masonry, reinforced solid masonry, reinforced hollow unit masonry, reinforced grouted masonry and reinforced pocket type walls. Effect of Infill 1. The stresses, in the infill wall, however, were found to increase with the increase in Young’s Modulus of elasticity due to the increase in stiffness of the system, attracting more forces to the infill. 2. The infill wall enhances the lateral stiffness of the framed structures; however, the presence of openings within the infill wall would reduce the lateral stiffness. 3. The fundamental period only slightly increases as the infill wall thickness increases, since the increase in thickness only increases the mass of the structure rather than its stiffness. 4. The infill was assumed to crack once the stress in the infill exceeded the ultimate compressive stress of the infill material. 5. The strength if infill in terms of its Young’s modulus (Ei) has a significant influence on the global performance of the structure. The structural responses such as roof displacements, inter-storey drift ratios and the stresses in the infill wall decrease with increase in (Ei) values due to increase in stiffness of the model. 6. The opening size of the infill has a significant influence on the fundamental period, inter-storey drift ratios, infill stresses and the structural member forces. Generally, they increase as the opening size increases, indicating that the decrease in stiffness is more significant than the decrease in mass. 7. The specific weight of reinforced masonry is smaller, the thermal and somniferous conductivity of the masonry is worse and it also has better resistance against fire and chemicals. 8. The wall can be loaded right after finishing the construction.
- 3. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 183 Fig 1: ‘Equivalent Diagonal Strut’ model for infill panel Fig 2: Masonry infill panels in framed structures To study the performance of masonry- in filled R.C frames under Brick infill wall condition, analytical investigations have been conducted. The aim of this study is to investigate the behavior of Brick masonry in-fill R.C Frames under lateral loading. The Analysis has been done using ETABS software. In this project report five different type of modals has been analyzed. 2. ANALYSIS Following data is used in the analysis of the RC frame building models 1. Type of frame: Special RC moment resisting frame fixed at the base 2. Seismic zone: III 3. Number of storey: G+9 4. Floor height: 3.5 m 5. Depth of Slab: 150 mm 6. Size of beam: (230 × 450) mm
- 4. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 184 7. Size of column: (230 × 600) mm 8. Spacing between frames: 5 m along both directions 9. Live load on floor: 3 KN/m2 10. Floor finish: 0.6 KN/m2 11. Materials: M 20 concrete, Fe 415 steel and Brick infill 12. Thickness of infill wall: 230 mm 13. Density of concrete: 25 KN/m3 14. Density of infill: 20 KN/m3 15. Type of soil: Medium 16. Response spectra: As per IS 1893(Part-1):2002 17. Damping of structure: 5 percent Model Specifications Grade of concrete : M20 Grade of Steel : Fe415 Beam Size : 0.23 x 0.45 m (for 3D modal) Column Size : 0.230 x 0.60 m Beam c/c Distance : 5 m (for all 3D modal) Column c/c Distance : 5 m (for all 3D modal) In-fill wall Material : Brick Material Properties Steel Reinforcement Type of Material - Isotropic Mass per Volume (ρ) - 7850kg/m3 Weight per Volume (W) - 78.50kN/m3 Modulus of Elasticity (E) - 2x105 N/mm2 Poisson’s ratio (µ) - 0.30 Co-efficient of Thermal Expansion-1.1x10-5 Yield Strength- 415N/mm2 Brick Masonry Infill Type of Material - Isotropic Mass per Volume (ρ) - 1800kg/m3 Weight per Volume (W) - 18kN/m3 Modulus of Elasticity (E) - 13500N/mm2 Poisson’s ratio (µ) - 0.16 Compressive strength of clay brick - 3.5N/mm2 Co-efficient of Thermal Expansion-5.5x10-6 Concrete Type of Material - Isotropic Mass per Volume (ρ) - 2500kg/m3 Weight per Volume (W) - 25kN/m3 Modulus of Elasticity (E) - 22000 N/mm2 Poisson’s ratio (µ) - 0.17 Co-efficient of Thermal Expansion-9.90x10-6 Characteristic compressive strength -25N/mm2 Models Case 1 - 3D 10 storey with in-fill wall. Case 2 - 3D 10 storey without in-fill wall. Case 3 - 3D 10 storey with brick in-fill cross walls Case 4 - 3D 10 storey with infill walls at lift portions Case 5 – 3D 10 storey with soft storey. 3. RESULTS AND DISCUSSIONS In this study, five different models of an eight storey building symmetrical in the plan are considered. Usually in a building 40% to 60% presence of Masonry infill (MI) are effective as the remaining portion of the Masonry Infill (MI) are meant for functional purpose such as doors and windows openings (Pauley and Priestley, 1992). In this study the buildings are modeled using 40 % Masonry Infill (MI) but arranging them in different manner as shown in the Figure 1 Following five different models are investigated in the study.
- 5. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 185 1. Model I : Bare frame 2. Model II : Masonry infill are arranged in outer periphery 3. Model III: Masonry infill are arranged in outer periphery with soft storey 4. Model IV: Masonry infill are arranged as inner core 5. Model V : Masonry infill are arranged as lift core TABLE 1: Parameters From ETAB And SAP Analysis PARAMETERS ETABS MODEL SAP MODEL Tx(Sec) 2.728 2.641 Ty(Sec) 2.0068 1.965 Wx(Hz) 2.303 2.379 Wy(Hz) 3.130 3.197 VBX(KN) 2108.31 2156.2 VBY(KN) 2650.44 2706.01 Fig 3: Graph showing displacements of Fig 4: Graph showing displacements of various stories(case 1) various stories(case 2) Fig 5: Graph showing displacements of Fig 6: Graph showing displacements of various stories(case 3) various stories(case 4)
- 6. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 186 Fig 7: Graph showing displacements of various stories(case 5) 4. DISCUSSIONS In this paper ten storey RC frame building models are studied that includes bare frame, infill frame and open first storey frame. The parameters which are studied are time period, natural frequency, base shear and storey drift. Fig 8: Graph showing comparison of displacement for all the cases in X direction 5. CONCLUSIONS In this paper seismic analysis of RC frame models has been studied that includes bare frame, infill frame, open first storey frame, cross shaped infill frame and infill at lift core frame. From the seismic analysis of RC frames following conclusions are drawn, 1) The seismic analysis of RC frames was conducted by considering the infill walls in the analysis. 2) Infill frames should be preferred in seismic regions than the open first storey frame, because the storey drift of first storey of open first storey frame is very large than the upper storey, this may probably cause the collapse of structure. 3) The presence of infill wall can affect the seismic behavior of frame structure to large extent, and the infill wall increases the strength and stiffness of the structure. 4) The seismic analysis of RC (Bare frame) structure leads to under estimation of base shear. Therefore other response quantities such as time period, natural frequency, and storey drift are not significant. The underestimation of base shear may lead to the collapse of structure during earthquake shaking. Therefore it is important to consider the infill walls in the seismic analysis of structure. 5) In case of an open first storey frame structure, the storey drift is very large than the upper storey, which may cause the collapse of structure during strong earthquake shaking. Therefore the infill frame structures will be the better option to prefer in the seismic regions. 6) While comparing periphery infill frame with cross shaped infill frame, both having same base shear but time period, natural frequency, displacements are varying. That means position of infill frames also having significance. If we are taking infill also in design account we can effectively use infill walls. 7) In case of cross shaped infill frames with infill at lift core frame, cross shape gives better result, that means it is having less displacement.
- 7. Proceedings of the International Conference on Emerging Trends in Engineering and Management (ICETEM14) 30 – 31, December 2014, Ernakulam, India 187 REFERENCES [1] Prof.R.Ravi, Prof.Dr.C.Manoharan, Experimental Studies on Characterising of seismic Performance of Reinforced Concrete Frames, IOSR Journal of Mechanical and Civil Engineering (IOSRJMCE) ISSN: Issue 1 2278-1684 Vol.2, July-August 2012, pp 08-24. [2] S.Niruba, K.V.Boobalakrishnan, K.M.Gopalakrishnan, Analysis of Masonry Infill In A Multi-Storied Building International Refereed Journal of Engineering and Science (IRJES) ISSN (Online) 2319-183X, Issue 3(March 2014), (Print) 2319-1821 Vol. 3, 2012, pp.26-31. [3] Kashif Mahmud1*, Md. Rashadul Islam and Md. Al-Amin, Study the Reinforced Concrete Frame with Brick Masonry Infill due to Lateral Loads, International Journal of Civil & Environmental Engineering IJCEE-IJENS [4] Haroon Rasheed Tamboli and Umesh.N.Karadi, Seismic Analysis of RC Frame Structure with and without Masonry Infill Walls. Indian Journal Of Natural Sciences: Vol.3 / Issue 14/, 2012. [5] IS 1893:2002 Criteria For Earthquake Resistant Design Of Structures, Part 1 General Provision and Buildings. [6] IS 4326: 1993 Earthquake Resistant Design And Construction Of Buildings, Code Of Practice. [7] Imran.I and L.Aryanto, Behaviour of reinforced concrete frames in filled with lightweight materials under seismic loads, Structural Engineering Research Journal, Indonesia, vol.11, Title no.2, 2009, pp 69-77. [8] Mehmet Baran and Tugrul Tankut, 2011Experimental study on seismic strengthening of reinforced concrete frames by precast concrete panels under seismic loading, ACI Structural Journal, vol.108, Title no.23, pp 227. [9] Pankaj Agarwal and Manish Shrikhande, 2010. Earthquake Resistant Design of Structures, Eight Edition, PHI Learning Private Ltd, New Delhi. [10] Rehan A.Khan, Seismic Reliability analysis of RCC building frame, International Journal of Earth Sciences and Engineering ,Title no. 0974, 2006, pp – 13. [11] Amin Ali Ahfid, Dr. R.K.Pandey, Er C S Mishra and Dr. Ajeet Kumar Rai, “Dynamic and Pushover Analysis of Three Dimensional Models of Buildings for Rigid Floor Diaphragm Idealization using ETAB”, International Journal of Civil Engineering & Technology (IJCIET), Volume 5, Issue 3, 2014, pp. 92 - 99, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.