Design of Reinforced Masonry

1. Prof. A. R. Santhakumar Visiting Professor IIT Madras Design of Reinforced Masonry in Buildings

6. Monadnock Building, Chicago, 1891, Burnham and Root, architects

7. Concept of Shear Wall System

8. Hanalei Hotel, San Diego

9. Types of Masonry Construction

10. Concrete Masonry Compression-test prisms

11. High-Rise Concept in Block Masonry

12. Holiday Inn Motel, a Round Bearing-wall Multi-storey Structure

13. One Storey Commercial Building

14. Some Examples of Two-directional Bearing/shear wall layouts

15. Examples of multi-directional bearing/shear wall layouts

16. Deep wall beams

17. Brick pier-and-panel garden walls

18. Serpentine walls

22. flexural mode of failure (flexural compression). With the improved shear resistance and high moment/shear ratio, crushing of compresses zones at the ends of the wall usually take place,

25. House Element Resist Horizontal Forces Two-story building

28. No Shear Wall at Garage

29. House Elements Resist Gravity

34. Seismic Force Distribution

40. The diaphragms are classified into three groups of relative flexibilities: rigid, flexible, and semi rigid.

41. It is assumed to tribute the horizontal forces to the vertical resisting elements in direct proportion to the relative rigidities of those elements. This premise stems from the fact that under a symmetrical loading, the rigid diaphragm, which in it self does not deform appreciably will cause each vertical element to deflect the same amount. Rigid diaphragms are capable of transferring lateral and torsional forces to the walls. Rigid diaphragm

42. It may be likened to a series spans extending between very rigid supports, (i.e. vertical resisting elements). It is assumed here that the relative stiffness of these non yielding supports is very great compared to that of the diaphragm, which therefore deflects as a beam. This beam, having no appreciable continuity across the supports, thus develops no negative moment over them which would affect the distribution of lateral load Flexible diaphragm:

43. These exhibits significant deflection under load, and also have sufficient stiffness to distribute a portion of their load to the vertical elements in direct proportion to the rigidities of those elements. Semi rigid diaphragm

44. Horizontal forces at any floor or roof level may be transferred to the foundation through the strength and rigidity of the side walls, called as shear walls. The design strength of shear walls is often governed by flexure. However, in low walls, the governing design criterion may be shear, Masonry shear walls can be described not only in terms of types of masonry used , but also as load- bearing , non load bearing , reinforced or unreinforced, solid or perforated rectangular or flanged and cantilevered or coupled. Vertical stability elements

48. Moment Shear Deflection of walls due to bending and shear deformations  c =  m +  v P P Ph P h

49. Rigidity of the pier =R c = =

50. Δ f Deflection of walls due to bending and shear deformations Rigidity of the pier = R f = P Ph/2 Ph/2 P P Moment Shear

51. Effect of aspect ratio on deflection due to shear Aspect ratio h/L Percentage deflection due to shear Cantilever wall Fixed end wall 0.25 92 98 1 43 75 2 16 43 4 5 16 8 1 4.5

52. 1 For squat walls (h/L < 0.25), rigidities based on shear deformations are reasonably accurate. 2 For (0.25<h/L<4) intermediate cantilever walls both deflections components should be include ‘d’ in the calculation of relative rigidities. For high (h/L) the effect of shear deformation is very small and rigidity based on flexural stiffness is reasonably accurate.

53. SEISMIC RESISTANCE OF RAT-TRAP BOND WALL AND FILLER SLAB SYSTEM

55. FIGURE 2 TYPICAL CROSS SECTION

56. The Building System

57. Rat – Trap Bond Masonry

58. Typical Corner Joint

59. Method of Construction

60. Advantages

61. Validation

62. Experimental setup EXPERIMENTAL SET - UP 2 2 5 2 3 0 1 5 0 2 3 0 9 2 0 2 3 0 1 5 0 2 3 0 6 6 0 1 5 0 2 3 0 # # # # # # # # # # O n e l a y e r b r i c k o n e d g e 1 5 M B 3 0 0 1 5 M B 3 0 0 1 5 M B 3 0 0 1 6 2 5 9 7 4 8 3 1 0 1 . 2 6 5 . 9 7 1 0 8 4 . 3 WALL UNDER TEST ELEVATION END VIEW 1. STRAILS 2. DEFORMAIONS 3. LOADS 4. FAILURE PATTERN

63. Data for 1 cubic metre

64. Earthquake Resistance

65. Test Procedure

66. Load vs Moment

67. Load Application

68. Specimen Details S.No. Name Load (N) Moment (N mm) Failure Between 1 450M1 650 292500 Brick and Concrete surface at the bottom level 2 450M2 18431 310500 Brick and Concrete surface at the bottom level 3 340M3 1440 597600 II and III level Bricks 4 340M4 6143 601750 II and III level Bricks 5 450M5 4733 647400 I and II level Bricks 6 450M6 7973 9337500 I and II level Bricks 7 340M7 90000 0 Vertical cracks on all four sides

69. Practical Case

70. Practical Case

71. Safe Cantilever Spans for Limiting Tension in Brickwork Safe Moment (Nmm) Axial Load (N) Safe Span of the Cantilever (L 1 )(mm) 1000 200000 574.9891 2000 325000 759.8557 3000 450000 911.9664 4000 575000 1044.287 5000 685000 1149.326 6000 775000 1229.175 7000 885000 1320.751 8000 940000 1364.414