MASONRY STRUCTURE DOS III UTSAV KOSHTI

What is Masonry ? Masonry is the building of structures from individual units laid in and bound together by mortar; the term masonry can also refer to the units themselves. The common materials of masonry construction are brick, stone, marble, granite, limestone, cast stone, concrete block, glass block and tile. Masonry is generally a highly durable form of construction. However, the materials used, the quality of the mortar and workmanship, and the pattern in which the units are assembled can significantly affect the durability of the overall masonry construction.

Classification of Walls-structural context Based on load bearing Load bearing masonry walls. Non-load bearing masonry walls. Based on construction Solid walls Veneered walls Reinforced walls Cavity walls

Load bearing masonry walls A load-bearing wall (or bearing wall) is a wall that bears a load resting upon it by conducting its weight to a foundation structure. The materials most often used to construct load-bearing walls in large buildings are concrete, block, or brick.

Application Of Load Bearing Wall Depending on the type of building and the number of stories, load- bearing walls are designed to the appropriate thickness to carry the weight above them. Without doing so, it is possible that an outer wall could become unstable if the load exceeds the strength of the material used, potentially leading to the collapse of the structure. HOUSING TALL BUILDINGS

Non-Load Bearing Wall Walls that are only intended to support themselves and the weight of the cladding or sheathings attached. Non load bearing walls provide no structural support and may be interior or exterior walls.

SOLID WALLS

SOLID WALLS Masonry units laid close together with all joints filled solidly with mortar. Solid walls are structurally bonded by metal ties, masonry headers or by joint reinforcement. Where solid masonry walls are used, insulation and mechanical equipment are often installed within a furred space on the interior side of the wall. Below grade, insulation is often placed on the exterior side of the wall.

Insulation In Solid Walls Slightly reduce the floor area of any rooms in which it is applied (the thickness of the insulation is around 100mm) Disruptive, but can be done room by room Requires skirting boards, door frames and external fittings to be removed and reattached Can make it hard to fix heavy items to inside walls – although special fixings are available is generally cheaper to install than external wall insulation

External Wall Insulation

External Wall Insulation Can be applied without interruption to the household  Does not reduce the floor area of your home Renews the appearance of outer walls  Improves weatherproofing and sound resistance. Fills cracks and gaps in the brickwork, which will reduce draughts Increases the life of your walls by protecting the brickwork Is best installed at the same time as external refurbishment work to reduce the cost Is not recommended if the outer walls are structurally unsound and cannot be repaired.

Reinforced Masonry Walls

Reinforced masonry is any type of brick, concrete or other type of masonry that is strengthened or fortified with the use of other building materials to increase resistance to deterioration due to weight bearing or other forms of stress One of the most common examples of reinforced masonry involves exterior walls that are created using concrete blocks or clay bricks. Along with the blocks or bricks, steel rods are worked into the structure, often using some type of vertical framework that aids in allowing the walls to bear up under its own weight, and the weight of the connecting walls and floors within the building.

The weaknesses of the masonry without reinforcement: the sensitivity to cracks the low flexural bearing capacity Reinforcing in brickwork is applied for two causes: masonry is brittle material and is very sensitive to cracking. Therefore, one part of the cracks can be prevented by using reinforcing bars or mesh embedded in the bed joint, or the size of cracks can be significantly decreased. The flexural (tension) bearing capacity of masonry increases considerably with reinforcing.

Veneered Masonry Wall

Veneered Masonry Wall A brick veneer wall is constructed by having a non-structural external layer, usually with bricks and it is backed by an air cavity. The innermost element of this type of wall is structural can consist of wood, metal framing or masonry. A brick veneer construction has many advantages over solid masonry. It shares some of the advantages of a cavity wall. A brick veneer masonry wall is light weight, thermally efficient and can help in reducing costs.

Advantages The airspace between the brick veneer wall and the structural element acts as a drainage system. The cavity can be insulated and this improves the thermal performance of the wall. The structural element can be constructed first and this allows the rest of the construction to proceed. The brick veneer can be completed simultaneously. A brick veneer construction takes less time to complete than a solid masonry wall which will give cost savings. A veneer wall will weigh much less than a solid wall. Since the weight is less, the cost of the foundation and structural support can be reduced.

Some examples of brick veneered masonry walls.

CAVITY WALLS

Cavity Wall The cavity wall method of construction was introduced in the northwest europe during the 19th century and gained the widespread use from 1920’s. In some early examples stones were used to tie the two leaves of the cavity walls together. Initially cavity widths were extremely narrow and were primarily implemented to prevent the passage of moisture into the interior of the building.

Cavity Wall The cavity walls consist of two skins seperated by a hollow space (cavity). The skins are commonly masonry such as brick or concrete block. Masonry is an absorbent material and therefore will slowly draw rainwater or even humidity into the wall. The cavity serves as a way to drain this water back out through weep holes at the base of the wall system or above windows. The reason cavity insulation keeps heat in is that the polymer and air in the cavity are good insulators.

Face wall A wall in which facing and backing of two different materials are bonded together to ensure common action under load.

Curtain wall A non-load bearing wall subject to lateral loads. It may be laterally supported by vertical or horizontal structural members, where necessary.

Column, Pier and Butress Column: An isolated vertical load bearing member, width of which does not exceed four times the thickness. Pier - A thickened. section forming integral part of a wall placed at intervals along the wall, to increase the stiffness of the wall or to carry a vertical concentrated load. Buttress-A pier of masonry built as an integral part of wall and projecting from either or both surfaces, decreasing in cross-sectional area from base to top.

Indian Standard for brick masonry IS 1905:1987 Code of practice for structural use of unreinforced masonry IS 2212:1962 Code of practice for brickwork SP 20: Masonry Design and Construction.

IS 1905: 1987 Codal Provisions for Column Design Table 1 Various Mix Proportion and strength of Mortar

IS 1905: 1987 Codal Provisions for Column Design Table 4 Effective Height of Wall

IS 1905: 1987 Codal Provisions for Column Design Table 5 Effective Length of Wall

IS 1905: 1987 Codal Provisions for Column Design Effective Height of Column

IS 1905: 1987 Codal Provisions for Column Design Table 8 Basic Compressive Stress for Masonry

IS 1905: 1987 Codal Provisions for Column Design Table 9 Compressive Stress Reduction: Factor takes into consideration the slenderness ratio of the element and also the eccentricity of loading.

IS 1905: 1987 Codal Provisions for Column Design Cl. 5.4.1.2 Area reduction factor This factor takes into consideration smallness of the sectional area of the element and is applicable when sectional area of the element is less than 0.2 m2. The factor, ka = 0.7 + 1.5 A, A being the area of section in m2.

IS 1905: 1987 Codal Provisions for Column Design Table 10 Shape Modification factor This factor takes into consideration the shape of the unit, that is, height to width ratio ( as laid ) and is given in Table 10. This factor is applicable for units of crushing strength up to 15 N/mm%