EFFECT OF HAUNCHED BEAMS IN MOMENT RESISTING RC FRAMES

Transcription

1 International Journal of Civil Engineering and Technology (IJCIET) Volume 8, Issue 9, September 217, pp , Article ID: IJCIET_8_9_134 Available online at ISSN Print: and ISSN Online: IAEME Publication Scopus Indexed EFFECT OF HAUNCHED BEAMS IN MOMENT RESISTING RC FRAMES Venna Mythilee Priyanka Department of Civil Engineering, Andhra University, Visakhapatnam, India M. Pavan Kumar Department of Civil Engineering, SVP Engineering College, Visakhapatnam, India Dr. G.V.S. Raj Kumar Department of IT, GITAM University, Visakhapatnam, India Duba Vishalakshi Department of Civil Engineering, Govt Polytechnic, Visakhapatnam, India ABSTRACT The need of experimental studies on the motorized behavior of reinforced concrete (RC) Haunched beams leads to difficulties in statistical and reliability analysis. This study performs the analysis of RC framed structure with Haunched beams. Structures composed of Haunched beams, have been recently adopted for many high-rise buildings. STAAD pro has been used for the analysis of RC framed structure with Haunched beams. This paper is concerned with the effects of stiffness attained by considering Haunched beams on the seismic response of a structure and the main objective is to carry out the linear static (seismic coefficient) and linear dynamic (response spectrum) analysis on RC building frames modelled with and without Haunched beams for ten storeys at all seismic zones in India considering IS 1893 (Part 1): 22 and compare the results of analysis (lateral displacements and natural period). From the results analysis, it was observed that there is an increase in the stiffness of RC frame with Haunched beams than that of the RC frame without Haunched beams. Key words: Haunched beams, Stiffness, RC frames, Lateral displacement, STAAD pro. Cite this Article: Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi. Effect of Haunched Beams in Moment Resisting RC Frames. International Journal of Civil Engineering and Technology, 8(9), 217, pp editor@iaeme.com

2 Effect of Haunched Beams in Moment Resisting RC Frames 1. INTRODUCTION Haunched beam is a beam whose cross section is thicker at the supports than in the middle of the span. Haunched beams are used in buildings for many reasons among them as they favor a more efficient use of materials to clear a given span or to provide a reasonable clear height for the storeys of buildings. Indeed, tapered elements in general and Haunched beams in particular have been traditionally difficult to model in a practical manner. This was the main reason for which most commercial software did not include them in their elements libraries for many years. In fact, it was in 2 s the leading worldwide commercial software for structural analysis such as STAAD pro started to include them in their element libraries. Reinforced concrete (RC) Haunched beams are widely used as bridges or portal frames and precast roof girders, there is a lack of studies in the literature investigating this topic Scarce in experimental studies is the main obstacle to include this topic in details by international building practice codes. As a result of various experimental studies (Nilson, et al. 211), it can be concluded that the behavior and failure of the RC Haunched beams differs as compared to prismatic section RC beams. The researchers (Tena colunga, 212), (Archundia-Aranda, et al. 213) proved that the depth variance along the beam has a clear influence on the shear behaviour as well as shear capacity (Albegmprli, et al. 215). During an earthquake, failure of structure starts at points of weakness. This weakness arises due to discontinuity in mass, stiffness and geometry of structure. The structures having this discontinuity are termed as irregular structures. Irregular structures contribute a large portion of urban infrastructure. Irregularities are one of the major reasons of failures of structures during earthquakes. For example structures with soft storey were the most notable structures which collapsed. So, the effect of irregularities in the seismic performance of structures becomes really important. Height-wise changes in stiffness and mass render the dynamic characteristics of these buildings different from the 'regular' building. According to IS 1893: 22, structure withstand moderate level of earthquake ground motion without structural damage, but possibly with some structural as well as non-structural damage. In present study, the earthquake analysis for ten storeyed buildings was done by both linear static analysis and linear dynamic (Response Spectrum) analysis. 2. METHODOLOGY The plan and elevation of ten storeyed reinforced concrete buildings with and without considering Haunched beams are shown in the fig 1& fig 2. Figure 1 Plan of the RC framed structure (All dimensions in m) editor@iaeme.com

3 Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi Figure 2 Elevation of 1 storeyed RC Framed Structure 2.1. Geometrical Configuration Ten storeyed reinforced concrete buildings which are modelled without Haunched beams and with Haunched beams are considered. Figure shows the plan of the three buildings. Storey height of each building is assumed as 3.m. Fig 3 shows the column positions of the RC building. Fig 4 and Fig 5 shows the 3D rendered view of RC frames without Haunched beams and RC frames with Haunched beams. Beam cross sections for ten storeyed RC model at seismic zone II, III, IV and V 23 mm x 63 mm. Column cross sections for ten storeyed RC model at seismic zone II, III, IV and V 38 mm x 75 mm. Beam Cross section for Haunched beam1: The width of the Haunched beam is constant that is 23 mm and the depth of the beam is varies from 4 mm to 63 mm.beam Cross section for Haunched beam2: The width of the Haunched beam is constant that is 23 mm and the depth of the beam is varies from 63 mm to 83 mm D views of the RC Framed Structures used for Analysis Figure 3 3D view of the RC frame structure without Haunched beams editor@iaeme.com

4 Effect of Haunched Beams in Moment Resisting RC Frames Figure 4 3D view of the RC frame structure with Haunched beam1 Figure 5 3D view of the RC frame structure with Haunched beam Structural Analysis and Design The steps required to analyse and design a structure using STAAD Pro V8i are represented by a flow chart as shown below: Figure 6 Flow chart showing Methodology of the Present Study editor@iaeme.com

5 Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi 3. RESULTS & DISCUSSIONS The results for linear static and linear dynamic analysis are calculated. The results are given for Mode number & natural period, lateral displacements and base shear of the RC frames with and without Haunched beams for ten storeys RC framed structure for seismic zones II, III, IV & V respectively Linear Static Analysis The analysis for load combinations is carried out for positive and negative X & Z directions after defining the seismic definition. The corresponding lateral displacements at each and every storey height from the ground level for the three models (RF, RFHB1 & RFHB2) with and without Haunched beams for the seismic zones II, III, IV & V are compared below. Case (i) Regular Frame (RF) Storey Height (m) Table 1 Lateral displacements of RF Lateral Displacement (mm) ZONE-II ZONE-III ZONE-IV ZONE-V Case (ii) Regular Frame with Haunched Beam1 (RFHB1) Storey Height (m) Table 2 Lateral displacements of RFHB1 Lateral Displacement (mm) ZONE-II ZONE-III ZONE-IV ZONE-V editor@iaeme.com

6 Lateral Displacement (mm) Lateral Displacement (mm) Effect of Haunched Beams in Moment Resisting RC Frames Case (iii) Regular Frame with Haunched Beam2 (RFHB2) Table 3 Lateral displacements of RFHB2 Storey Height (m) Lateral Displacement (mm) ZONE-II ZONE-III ZONE-IV ZONE-V Comparison of Lateral Displacement for RF, RFHB1 & RFHB RF RFHB1 RFHB Figure 7 Comparison of Lateral Displacement of RC frame with and without Haunched Beams (RFHB1, RFHB2) at seismic Zone-II obtained by Linear Static Analysis Figure 8 Comparison of Lateral Displacement of RC frame with and without Haunched beams (RFHB1, RFHB2) at seismic Zone-III obtained by Linear Static Analysis editor@iaeme.com

7 Lateral Displacement (mm) Lateral Displacement (mm) Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi Figure 9 Comparison of Lateral Displacement of RC frame with and without Haunched Beams (RFHB1, RFHB2) at seismic Zone-IV obtained by Linear Static Analysis Figure 1 Comparison of Lateral Displacement of RC frame with and without Haunched Beams (RFHB1, RFHB2) at seismic Zone-V obtained by Linear Static Analysis. From the above figures 7, 8, 9 and 1, it is observed that there was a decrease in lateral displacement of RC frame with Haunched beams (RFHB1& RFHB2) when compared to the RC frame without Haunched beams. The percentage of decrease in the lateral displacements of the RC frames with Haunched beams for RFHB1 & RFHB2 at seismic zone II & III are 12% and 47, seismic zone IV & V are 15% and 48% respectively when compared with regular frame without Haunched beams Linear Dynamic Analysis The analysis for load combinations is carried out for positive X & Z directions after defining the Response Spectrum load case. The corresponding lateral displacements and base shear at each and every storey height from the ground level and the natural period with respect to modes for the three models (RF, RFHB1& RFHB2) with and without Haunched beams for the seismic zones II, III, IV & V are compared below editor@iaeme.com

8 Effect of Haunched Beams in Moment Resisting RC Frames Case (i) :Regular Frame Lateral isplacements Table 4 Lateral displacements of Regular Frame Storey Height (m) Lateral Displacement (mm) Zone-II Zone-III Zone-IV Zone-V Case(ii): Regular Frame with Haunched Beam1 Table 5 Lateral displacements of RFHB1 Storey Height (m) Lateral Displacement (mm) Zone-II Zone-III Zone-IV Zone-V Case (iii): Regular Frame with Haunched Beam2 Table 6 Lateral displacements of RFHB2 Storey Height (m) Lateral Displacement (mm) Zone-II Zone-III Zone-IV Zone-V editor@iaeme.com

9 Lateral Displacement(mm) Lateral Displacement(mm) Lateral Displacement(mm) Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi Comparison of Lateral Displacement for RF, RFHB1 & RFHB Figure 11 Comparison of Lateral Displacement of RC frame with and without Haunched beams (RFHB1, RFHB2) at seismic Zone-II obtained by Linear Dynamic Analysis Figure 12 Comparison of Lateral Displacement of RC frame with and without Haunched beams (RFHB1, RFHB2) at seismic Zone-III obtained by Linear Dynamic Analysis Figure 13 Comparison of Lateral Displacement of RC frame with and without Haunched beams (RFHB1, RFHB2) at seismic Zone-IV obtained by Linear Dynamic Analysis editor@iaeme.com

10 PERIOD (Sec) Lateral Displacement(mm) Effect of Haunched Beams in Moment Resisting RC Frames Figure 14 Comparison of Lateral Displacement of RC frame with and without Haunched beams (RFHB1, RFHB2) at seismic Zone-V obtained by Linear Dynamic Analysis. From the Figures 11, 12, 13 and 14, it is observed that there was a decrease in lateral displacement of RC frame with Haunched beams (RFHB1&RFHB2) when compared to the RC frame without Haunched beams. The percentage of decrease in the lateral displacements of the RC frames with Haunched beams for RFHB1 & RFHB2 at seismic zone II are 15% and 47%, seismic zone III & IV are 16% and 47%, seismic Zone-V are 17% and 47% respectively when compared regular frame without Haunched beams Natural Period and Frequency The Natural period and frequency for a Regular Frame(RF), Regular frame with Haunched beam1(rfhb1) and Regular frame with Haunched beam2(rfhb2) at each mode are given below. Table 7 Frequency and time period for mode shapes Mode RF RFHB1 RFHB2 Frequency Period Frequency Period Frequency Period Hz seconds Hz seconds Hz seconds Comparison of natural period of RC frame with and without Haunched beams MODE RF RFHB1 RFHB2 Figure 15 Comparison of natural period of RC frame with and without Haunched beams (RFHB1, RFHB2) editor@iaeme.com

11 Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi The percentage of decrease in the natural period of the RC frameswith Haunched beams1 for the Mode numbers 1, 2, 3, 4, 5 & 6 are 17%, 18%, 17%, 34%, 39% & 4% respectively when compared regular frame. The percentage of decrease in the natural period of the RC frames with Haunched beam2 for the Mode numbers 1, 2, 3, 4, 5 & 6 are32%, 35%, 35%, 34%, 39% & 4% respectively when compared regular frame Base Shear The base shear of a Regular frame with Haunched beam1 at each and every storey height from the ground level with respect to all zones are given below Table 8 Base Shear of Regular frame HEIGHT BASE SHEAR (KN) Zone-II Zone-III Zone-IV Zone-V Table 9 Base Shear of RFHB1 HEIGHT BASE SHEAR (KN) Zone-II Zone-III Zone-IV Zone-V Table 1 Base Shear of RFHB2 HEIGHT BASE SHEAR (KN) Zone-II Zone-III Zone-IV Zone-V editor@iaeme.com

12 Effect of Haunched Beams in Moment Resisting RC Frames From the above, it was observed that there was an increase in Base Shear of RC frame with Haunched beams (RFHB1&RFHB2) when compared to the RC frame without Haunched beams. The percentage of increase in the Base Shear of the RC frames with Haunched beams for RFHB1& RFHB2 at all seismic Zones are 17% and 25% respectively when compared with regular frame without Haunched beams. 4. CONCLUSIONS The analysis of RC frames with and without Haunched beams has been carried out for ten storeyed model at all seismic zones in India as per code IS: 1893:22 by using linear static analysis and linear dynamic analysis. Based on the analysis of results and discussions thereon the following conclusions are shown For ten storeyed regular RC frames, it was observed that there was an increase in lateral displacement of RC frame at seismic Zones III, IV & V are 37%, 58% and 72% respectively by linear static analysis and 37%, 58% and 72% respectively by linear dynamic analysis with respect to seismic Zone II. For ten storeyed regular RC frame with Haunched beam1, it was observed that there was an increase in lateral displacement of RC frame at seismic Zones III; IV & V are 36%, 57% and 71% respectively by linear static analysis and 36%, 58% and 71% respectively by linear dynamic analysis with respect to Zone II. For ten storeyed regular RC frame with Haunched beam2, it was observed that there was an increase in lateral displacement of RC frame at seismic Zones III, IV & V are are 37%, 58% and 71% respectively by linear static analysis and 37%, 58% and 72% respectively by linear dynamic analysis with respect to Zone II. For RC frame with Haunched beam1, it was observed that there was a decrease in lateral displacement when compared to the regular RC frame are 12%, 14%, 15% and 15% respectively by linear static analysis and 15%, 16%,16 % and 17% respectively by linear dynamic analysis with respect to seismic Zones II, III, IV & V. For RC frame with Haunched beam2, it was observed that there was a decrease in lateral displacement when compared to the regular RC frame are 47%, 47%,48% and 48% respectively by linear static analysis and 47%, 47%,47 % and 47% respectively by linear dynamic analysis with respect to seismic Zones II, III, IV & V. From the results of a ten storeyed RC frame with Haunched beam1, it was observed that there is a decrease in the natural period of the frame with Haunched beams when compared to the frame without Haunched beams are 17%, 18%, 17%, 34%, 39% & 4% for the mode numbers 1, 2, 3, 4, 5 & 6 respectively. From the results of a ten storeyed RC frame with Haunched beam2, it was observed that there is a decrease in the natural period of the frame with Haunched beams when compared to the frame without Haunched beams are 32%, 35%, 35%, 34%, 39% & 4% for the mode numbers 1, 2, 3, 4, 5 & 6 respectively. From the results, it was observed that there was an increase in Base shear of RC frame with Haunched beams (RFHB1&RFHB2) when compared to the RC frame without Haunched beams. The percentage of an increase in the Base shear of the RC frames with Haunched beams for RFHB1& RFHB2 are 17% and 25% respectively. In view of the above observations, clearly there was an increase in the stiffness for RC frame with Haunched beam1 compared with the regular RC frame and there was an increase in the stiffness for RC frame with Haunched beam2 compared with the RC frame with Haunched beam1. Thus, by considering Haunched beams, effective stiffness models can be generated editor@iaeme.com

13 Venna Mythilee Priyanka, M. Pavan Kumar, Dr. G.V.S. Raj Kumar, Duba Vishalakshi REFERENCES [1] Albegmprli, H.M., Çevik, A., Gülsan, M.E. and Kurtoglu,A.E. (215) Reliability analysis of reinforced concrete haunched beams shear capacity based on stochastic nonlinear FE analysis, Computers and Concrete journal Vol. 15, No. 2, pp [2] Archundia-Aranda, H.I. Tena-Colunga, A. and Grande-Vega, A (213) Behavior of reinforced concrete Haunched beams subjected to cyclic shear loading, Engineering Structures journal, Volume 49,pp [3] Abd el-rahman megahid, Rashwan M. M. and Ahmed mohamed sayed ( 21) Static Behaviour of Reinforced High Strength Concrete haunched beams strenghened by using Epoxy bonded external steel plates, Journal of Engineering Sciences, Assiut University, Vol. 38, No. 6, pp [4] Arturo Tena-Colunga,, Hans I. Archundia-Aranda and Oscar M. Gonz alez-cuevas (28) Behavior of reinforced concrete Haunched beams subjected to static shear loading, Science direct journal, Engineering Structures 3, pp [5] A.K. Sinha and Sharad Singh, Seismic Protection of RC Frames Using Friction Dampers. International Journal of Civil Engineering and Technology, 8(2), 217, pp [6] Hans I. Archundia-Aranda and Arturo Tena-Colunga (28) Cyclic behavior of reinforced concrete Haunched beams failing in shear, 14 th World Conference on Earthquake Engineering, October 12-17, Beijing, China. [7] Hasan M. Albegmprli1, Abdulkadir C evik, M. Eren Gülşan and Ahmet Emin Kurtoglu (215) Reliability analysis of reinforced concrete Haunched beams shear capacity based on stochastic nonlinear FE analysis, Computers and Concrete, Vol. 15, No. 2, [8] M.E. Ephraim and T.C. Nwofor, Experimental Modeling of In Filled RC Frames with Opening, International Journal of Civil Engineering and Technology, 7(2), 216, pp [9] Nilson, A Darwin, D. and Dolan, C. (211), Design of Concrete Structures, (14th Edition), Mc Grew Hill, New York, USA. [1] Rombach,G. and Nghiep, V.H. (211), Shear strength of Haunched concrete beams without transverse reinforcement Beton-und Stahlbetonbau journal, Volume 16, Issue 1, pp [11] Tena-Colunga, Arturo (212) Lateral Stiffness of Reinforced Concrete Moment Frames with Haunched Beams, 15 th World Conference on Earthquake Engineering LISBOA. [12] Tena-Colunga A. and Martínez-Becerril, L.A.(213) Approximations of lateral displacements of reinforced concrete frames with symmetric haunched beams in the elastic range of response using commercial software, Practice Periodical on Structural Design and Construction journal, Volume 18, issue 2, pp [13] Vu Hong Nghiep (211) Shear Design of Straight and Haunched Concrete Beams without Stirrups, Dissertation editor@iaeme.com