Seismic Behaviour of Multistorey Shear Wall Frame Versus Braced Concrete Frames

Abstract

Where A h = 2 Z R I g Sa ……………….(A) Distribution of seismic force along height of building     n i 1 i i i 2 i i B h W h W V Q …………………….(B) Calculate Design base shear (V B) by using equation A and distribute along the height of building at each floor by using equation B. IV. SELECTION OF STRUCTURE To study the behavior of shear-wall frame and braced concrete frame, an building with simple symmetric plan having three bays in both the directions is selected(Fig. 1), Different shear wall frames and braced concrete frames are developed by placing shear walls and braced elements at various selected locations in 15-storey building. It has total eight plane frames in both the all directions. Four column locations (a, b, c, d respectively) of each plane frame are treated as shear-wall locations and three bays (B1, B2, B3 respectively) are treated as brace element locations. Solid cantilever shear-walls having width 1.5m in rectangular section are adopted. The X, K, IV-type brace patterns are adopted. In all a total of 24 frames have been analysed. Fig. 1 Plan of building Preliminary data:-1. Size of all beams = 230 x 450 mm 2. Size of all columns = 300 x 600 mm 3. Size of shear-walls = 300 x 1500 mm 4. Size of bracings = 230 x 450 mm 5. Storey height = 4500 mm 6. Frame Spacing in both direction = 6000 mm 7. Slab thickness = 150 mm 8. Wall thickness = 120 mm (Brick masonry) V. SHEAR WALL FRAME SYSTEMS In these systems, shear-wall is provided in different manners at various selected locations from bottom floor to top floor. Accordingly different systems (frames) developed are as follows. 1. Placing shear-wall at one location out of four locations at a time and repeating it for remaining locations, thus four systems are developed 2. Placing shear-wall at two locations out of four locations at a time in different manner, another four systems are developed 3. Placing shear-wall at first three locations, only one system is developed 4. Placing shear-wall at all locations, another one system is developed In all, total 10 systems are developed. These ten systems are used for shear-wall width '1.5 m' resulting 10 systems with constant width from bottom to top floor (Fig.2). Fig. 2 Section of Shear wall Frame VI. BRACED CONCRETE FRAME SYSTEMS In these systems, brace elements are provided in different manner at various selected locations from bottom floor to top floor. Accordingly different systems developed are as follows. 1. Placing brace X and K type elements at one location out of three locations at a time and repeating it for remaining locations, thus Six system are developed 2. Placing brace X, K and IV type elements at two locations out of three locations at a time in different manner, another six systems are developed 3. Placing brace X and K type elements at all locations, two more system is developed. In all, 6 systems are developed each for X and K-type brace patterns (total 12 systems). Placing brace elements in two adjacent bays to form 'inverted V-type' brace pattern in different manner, thus two additional systems are developed (Fig.3).