Comparative Study of the Seismic Performance of Rcc Building with Ribbed Slab and Grid Slab

Abstract

 To evaluate and compare the seismic behaviour of multistoried RCC building having ribbed slab vs grid slab in high-intensity earthquake based upon various criteria 3. LITERATURE SURVEY:  Salman I. Khan and Ashok R. Mundhada (2015) have conducted a comparative research on multistoried R.C.C buildings with flat slab and grid slab, the dynamic analysis (response spectrum method) was performed using ETABS software to three different high rise buildings having 12, 15 & 18 stories, the study can be epitomized that gird slab has better performance than the flat slab based upon grid slab has 4% less base shear and lateral displacement additional to flat slab has significantly more story drift.  Makode R K and Akhtar (2014) have compared the seismic response of multistoried structures (12-storey building) with flat and grid slabs using response spectrum method, the study concludes that at the columns in the center of the plan was less in grid slab as compared to the building with flat slab, moreover at each storey the building with grid performed less storey drift than flat slab.  B. Doering, C. Kendrick and R.M. Lawson (2013) studied the thermal capacity of a composite slabs and ribbed slab along with a comparative study to flat slab system. The research resulted in that composite slabs generates a maximum heat compare to flat slab according to numerical studies the difference is approximately 20%  Bothara SD and Varghese V (2012) have assessed the seismic response of both grid slab and flat slab in this study 9-Storey building was adopted to evaluate the behaviour by using response spectrum method, until 4 stories the slabs performance was identical, however the difference is clear in terms of storey drift for more than 4 storey building. 4. MODELLING AND ANALYSIS: In this research, a regular existing plan was considered with regard to study the behaviour of multistory RCC structure along with the comparative study of the response of grid slab ribbed slab subsequently 6 different cases of multistory RCC structure were adopted. 4.1 Building specifications: The grade of concrete: M30 The grade of longitudinal rebar: Fe 415 N/mm 2 The seismic zone: IV Importance factor: 1 Soil type: Medium soil (type (II)) Response reduction factor: 4.5 4.2 Structural elements dimension: 4.2.1 Slabs properties: Grid slab and hollow block ribbed slab are analogous in diversified aspects for instance in construction the two systems comprise of ribs and segments of slabs this which makes them comparable in the table (1) and table (2) the show selected slabs specifications. Table 1: slab grid dimensions Grid slab property data Overall Depth 230 mm Slab thickness 70 mm Stem width at top 180 mm Stem width at bottom 180 mm Ribs spacing parallel to X 1500 mm Ribs spacing parallel to Y 1500 mm Table 2: slab ribbed dimensions Ribbed slab property data Overall Depth 230 mm Slab thickness 70 mm Stem width at top 150 mm Stem width at bottom 180 mm Ribs spacing (perpendicular to Ribs direction) 500 mm Ribs direction is parallel to Y direction 4.2.2 Beams and shear wall properties: In all the models two beams categories were utilized the internal beams with a rectangular cross-section having 500mm width and 250mm depth, plus exterior a rectangular beams owning dimension of 250mm and 450mm width and depth respectively. Nevertheless the shear walls thickness 250mm has been maintained in all models. 4.2.3 Column properties: In order to have a comprehensive understanding of the response of the various slab system in the reinforced concrete residential building, three different models were adopted depending on increasing the number of floors [7]. The followed analysis cases are 6 models 3 for each slab system using 4, 6, 8 storied OMRF building, for every case the columns were divided into three categories based on the amount of load acting on the column. The first case categories dimensions are (250 mm *250 mm), (250mm*400 mm), and (300 mm*400 mm) breadth and depth respectively, for the second case the dimensions selected such that (250 mm*300 mm) for the first category (250 mm*600 mm) and (300 mm*650 mm) for the second and third category however, for the last analysis case columns are distributed following (250 mm*360 mm), (300 mm*650 mm) and (350 mm*700 mm) for the three divisions respectively.