COMPARISION OF STRENGTH PARAMETERS BETWEEN RCC FRAME AND
SHEAR WALL FRAME USING PUSHOVER ANALYSIS
A.L.Deepak
N.Jitendra Babu
Seife Getachew
Lecturer Asst.Professor Lecturer
Bule Hora University K.L. University Bule Hora University ETHIOPIA INDIA ETHIOPIA
ABSTRACT
This paper deals with the non-linear (pushover) analysis of a six storey RCC Frame and a SHEAR WALL Frame subjected to various kinds of loads. Both the structures are considered in the present study. The analysis has been carried out using ETABS software. Pushover curves have been developed and compared for both the cases. It was observed that the base force increased up to 20.6%. It has been observed that the RCC Frame with Shear wall is more stable to displacement than that of plane RCC Frame.
Keywords: Pushover Analysis, plane RCC Frame and RCC Shear Wall Frame.
INTRODUCTION:
The static pushover analysis is becoming a popular tool for seismic performance evaluation of existing and new structures. The expectation is that the pushover analysis will provide adequate information on seismic demands imposed by the design ground motion on the structural system and its components.
The pushover procedure could be categorized into two groups: displacement-based loading and force-based loading, Antoniou and Pinho[2004]. Displacement-based procedure, the analysis is carries until the target displacement equals to the top displacement of the structure. Force controlled pushover procedure is that the analysis is
carries out estimating the total force acting on the structure.
The main objective of the paper is to study the performance of RC frames and RCC shear walled frames under lateral loads and change in their modal properties under push.
This paper deals with the non linear analysis of an RCC frame and also the non-linear analysis of an RCC frame with shear walls done for lift walls on both sides.
LINEAR STATIC ANALYSIS (LSA) OF
FRAMES:
Linear static analysis of both the frames is carried out in ETABS. All the general loads are considered for the frames with slab at each floor.
The plan considered with column placement is shown below.
Fig: 1 RCC Frame without Shear Wall.
Fig: 2 RCC Frame with Shear Wall.
CASE: 1 Linear Static Analysis (LSA) of
RCC Frame without Shear Wall:
The frame was considered with six story’s (Stilt + G+6) with no irregularities in plan and elevation i.e., frame on plane ground
MEMBER PROPERTIES:
All the beams in the frame were sized to 0.3m X 0.45m
All the columns in the frame were sized to 0.3m X 0.6m
The slab of 0.1m thickness was assigned to each floor.
MEMBER LOADING:
All the members were assigned the following loadings.
Self Weight
Dead Load (member load) --- 10 KN/m
Dead Slab Load---- 4.5 KN/m
Live Load--- 3 KN/m
Earth Quake Loading-- as per IS 1893:2002
It was assumed that the wind force was not governing the frame efficiency.
The failure beams members in the analysis appear in red colour in the below figure: 3
No failure of member was observed in the analysis.
Fig.3 (Failure members in case 1)
CASE: 2 Linear Static Analysis (LSA) of
RCC Frame with Shear Wall:
The frame was considered with six story’s (Stilt + G+6) with no irregularities in plan and elevation i.e., frame on plane ground
MEMBER PROPERTIES:
All the beams in the frame were sized to 0.3m X 0.45m.
All the columns in the frame were sized to 0.3m X 0.6m.
The slab of 0.1m thickness was assigned to each floor.
The shear wall in the frame was sized to 1.83mX0.23m.
MEMBER LOADING:
All the members were assigned the following loadings.
Self Weight
Dead Load (member load) --- 10 KN/m
Dead Slab Load---- 4.5 KN/m
Live Load--- 3 KN/m
Earth Quake Loading--- as per IS 1893:2002
It was assumed that the wind force was not governing the frame efficiency.
The failure beams members in the analysis appear in red colour in the below figure: 4
All the outer most columns are subjected to failure.
All the top most edge beams are subjected to failure.
Some of the intermediate beams are also subjected to failure.
All the passed members are designed and the reinforcement details are displayed on the top of the members.
Fig.4 (Failure members in case 2)
NON-LINEAR STATIC ANALYSIS (NLSA)
OF FRAMES:
In Fig: 3 & Fig: 4 it was observed the analysis results of RCC frame with and with-out shear wall. The failure and passed members were represented in different colours.
hinges corresponding to the different levels were represented in their respective colours.
As per ATC 40 the elastic zone is categorized as below.
Point ‘A’ corresponds to the unloaded condition
Point ‘B’ corresponds to the onset of yielding.
Point ‘C’ corresponds to the ultimate strength.
Point ‘D’ corresponds to the residual strength.
Immediate Occupancy (IO) Life safety (LS)
Collapse prevention (CP)
The (IO- LS) zone in dark blue colour, (LS- CP) in light blue colour and CP in green colour,
Nodes below IO zone are in pink colour. Nodes beyond CP zone are in yellow,
orange and red colours depending on the severity.
Fig.5 Performance levels (ATC 40)
Case1. RCC Frame without Shear Wall:
The structure shown in the Fig:1 was developed to a six storey frame ( G+Stilt+6) with no irregularities in plan and elevation i.e., frame on plane ground
MEMBER PROPERTIES:
All the beams in the frame were sized to 0.3m X 0.45m.
All the columns in the frame were sized to 0.3m X 0.6m.
The slab of 0.1m thickness was taken for the analysis purpose and assigned to each floor.
It was assumed that the wind force was not governing the frame efficiency.
The failure nodes are shown in the below fig.6 with their corresponding zones from the Non-linear Static Analysis.
The nodes in the ground floor are in dark blue and pink colour which implies the zone as Immediate Occupancy to Life Safety (IO-LS)
Fig.6 (Nodes corresponding to different
zones for RCC Frame)
Case2. RCC Frame with Shear Wall:
The structure shown in the Fig:1 was developed to a six storey frame ( G+Stilt+6) with no irregularities in plan and elevation i.e., frame on plane ground
MEMBER PROPERTIES:
All the beams in the frame were sized to 0.3m X 0.45m.
All the columns in the frame were sized to 0.3m X 0.6m.
The shear wall in the frame was sized to 1.83mX0.23m.
The slab of 0.1m thickness was assigned to each floor.
It was assumed that the wind force was not governing the frame efficiency.
The failure nodes are shown in the below fig.7 with their corresponding zones from the Non-linear Static Analysis.
The nodes in the ground floor are in dark blue and pink colour which implies the zone as Immediate Occupancy to Life Safety (IO-LS)
Similarly the nodes on the structure are representing their corresponding zone which can be seen in the below figure.7.
All the nodes of the top floor are in pink colour representing their occurrence below IO level.
All the nodes in mid floors are beyond CP zone.
All the nodes represented in green colour represent their zone as CP.
Fig.7 (Nodes corresponding to different
COMPARISION OF PUSHOVER CURVES:
Pushover analysis for RCC frame and RCC Frame with Shear Wall were carried out and the pushover curves were determined with Displacement is represented on X-axis and Base-Reaction on Y-axis. The Comparision is carried out for the curves in both the cases.
Comparision of Results:
The Comparision is carried out for the values obtained in Displacement and Base Reaction for both the cases.
The maximum displacement that the RCC frame can withstand up to the elastic limit is 7.96x10-2 m and the base reaction for this displacement is 7.783 x103 KN.
The maximum displacement that the RCC frame with Shear Wall can withstand up to the elastic limit is 6.32x10-2 m and the base reaction for this displacement is 9.72 x103 KN
In the above comparison the base shear resisted by the RCC Frame without shear wall for a maximum displacement of 79.6 mm is 7783 KN. and for the RCC Frame with shear wall the base shear and the maximum displacement values are 9720 KN. an d 63.2 mm r espectivel y.
A RCC Frame with shear wall can resist 1937 KN (i.e., 19.9%) more base shear than that of a plane RCC Frame up to the elastic limit and the displacement decreased was about 20.6 %.
Table :1
Structure Displacement Base Shear
RCC frame 79.6 mm 7783 KN.
RCC frame with Shear
Fig: 8 Pushover curve for RCC Frame
Fig: 9 Pushover curve for RCC Frame with Shear wall.
CONCLUSIONS:
RCC Structure with Shear Wall is more stable and resistant to Base Shear and Displacement than that of normal RCC Frame.
An RCC Shear walled Structure can resist 19.9% more base shear than that of a normal RCC Frame.
As the RCC frame was provided with shear walls in lift walls, the displacement was reduced by 20.6%.
REFERENCES:
1. Art Chianello, Rupa Purasinghe “Push
Over Analysis Of A Multi-Storey
Concrete Perforated Shear Wall” 29th
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August 2004, Singapore.
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Report No. SSC 96-01. Redwood City (CA): Applied Technology Council; 1996.
3. FEMA. NEHRP guidelines for the seismic
rehabilitation of buildings (FEMA 273).
Washington (DC): Building Seismic Safety Council; 1997.
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8-9 feb-2012, Istanbul.
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