What Is Permissible Stress in Brick Masonry
Permissible stress in brick masonry refers to the maximum stress that can be applied to the bricks without causing failure or damage.
It is determined by factors such as the type and strength of bricks, the strength of the mortar used, and the slenderness ratio of the masonry structure.
These factors collectively determine the load-bearing capacity of the brickwork, ensuring that it remains structurally safe and stable.
Did You Know?
1. In brick masonry, permissible stress refers to the maximum amount of stress that a brick can withstand before it fails or experiences a permanent deformation.
2. The concept of permissible stress in brick masonry is crucial because it ensures that buildings and structures made of bricks can safely withstand the loads and forces they encounter over time.
3. The permissible stress in brick masonry varies depending on factors such as the type and grade of the brick, mortar strength, and the weather conditions in the area where the structure is built.
4. Surprisingly, the permissible stress in brick masonry can be affected by the color of the bricks used. Dark-colored bricks absorb more heat, leading to expansion and potentially lower permissible stress compared to light-colored bricks.
5. To accurately determine the permissible stress in brick masonry, engineers typically conduct tests that involve subjecting brick samples to different load conditions, simulating the stresses the bricks would experience in real-world situations. These tests help ensure the safety and durability of brick structures.
Type And Strength Of Bricks
Brick masonry is a widely used construction method known for its durability and versatility. The performance of brick masonry structures largely depends on the type and strength of bricks used. Bricks can be classified into various types, such as clay bricks, concrete bricks, and sand-lime bricks, each with its own unique properties.
When considering permissible stress in brick masonry, it is crucial to factor in the compressive strength of bricks. The compressive strength refers to the ability of a brick to resist crushing under a specific load. This strength is determined through laboratory testing, where bricks are subjected to axial compression until failure occurs. The permissible stress in brick masonry relies on these compressive strength values, ensuring that the brick units can sustain the expected loads without excessive deformation or failure.
It is important to note that the permissible stress varies for different types of bricks. For instance, clay bricks tend to have higher compressive strength compared to concrete bricks, allowing them to withstand greater stress. Therefore, in the design and construction of masonry structures, the type of bricks used must be carefully considered to ensure that the permissible stress limits are not exceeded.
Strength Of Mortar
Apart from the type and strength of bricks, the strength of mortar plays a significant role in determining the permissible stress in brick masonry. Mortar acts as a binding agent between bricks, distributing the applied loads evenly and transferring them to the supporting elements. The strength of mortar directly affects the overall strength and stability of the masonry structure.
The compressive strength of mortar is also determined through laboratory testing. It signifies the ability of the mortar to withstand compressive forces without failure. The type and ratio of the constituents used in the mortar, such as cement, sand, and water, influence its strength. The permissible stress in brick masonry takes into account the strength of mortar, ensuring that it can adequately transmit loads and maintain the integrity of the structure.
It is worth mentioning that different types of bricks may require specific types of mortar to achieve optimal performance. For instance, clay bricks may need a lime-based mortar, while concrete bricks may require a cement-based mortar. By selecting the appropriate mortar with the right strength, the permissible stress of the masonry can be maintained within acceptable limits.
- Different types of bricks may require specific types of mortar for optimal performance:
- Clay bricks may require a lime-based mortar.
- Concrete bricks may require a cement-based mortar.
Slenderness Ratio
The slenderness ratio refers to the ratio of the height of the masonry panel to its thickness. It is an important parameter in determining the permissible stress in brick masonry, especially in walls subjected to lateral loads like wind or earthquakes. The slenderness ratio affects the stability and resistance of the masonry against buckling or collapse.
As the slenderness ratio increases, the permissible stress in brick masonry decreases. Higher ratios result in increased flexural stresses, reducing the ability of the masonry to withstand applied loads. Careful consideration of the slenderness ratio is essential during the design and construction stages to ensure that the masonry is capable of safely resisting the anticipated forces.
In conclusion, understanding the permissible stress in brick masonry is crucial for designing and constructing structurally sound buildings. The type and strength of bricks, along with the strength of the mortar, play a vital role in determining these permissible stress limits.
- The slenderness ratio of masonry walls must also be considered to ensure the overall stability and integrity of the structure.
- Guided by these principles, engineers and masons can ensure the long-term durability and safety of brick masonry structures.
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Frequently Asked Questions
What is meant by permissible stress?
Permissible stress refers to the maximum level of stress that a material can endure without experiencing failure or any significant deformation under a specific loading condition. This measure, also known as working stress, determines the safety and durability of a material in various applications. Factors such as material properties, environmental conditions, and the type of loading applied can significantly influence the permissible stress level. These factors must be carefully assessed to ensure the material’s integrity and prevent any potential damage or failure within a given system or structure, thereby ensuring the overall safety and reliability of the application.
What is the permissible compressive stress of brick?
The permissible compressive stress of brick depends on the type of brick being used. For first-class brick, the permissible compressive stress is 105 kg/cm², which indicates a high resistance to compression. On the other hand, a second-rate brick can withstand a permissible compressive stress of 70 kg/cm². Sun-dried brick, which has a lower compressive strength, can tolerate a permissible compressive stress between 15 and 25 kg/cm². These permissible compressive stress values provide a guideline for determining the maximum amount of pressure that can be applied to brick structures without causing failure.
How will you determine the permissible stress in masonry?
To determine the permissible stress in masonry, it is important to consider the actual dimensions of the structure rather than nominal measurements. For non-engineered masonry, the stresses applied should not surpass the allowable limits outlined in the ANSI Standard Building Code Requirements for Masonry (A41. 1). These permissible stresses can be conveniently found in Table 11.4, serving as a useful reference for assessing the structural integrity of the masonry. By taking into account the actual dimensions and adhering to the allowable stress limits, one can ensure the safety and durability of the masonry construction.
What is the permissible value of stress?
The permissible value of stress in steel structures is a critical consideration in design. Primarily, the maximum stress that can be applied without causing failure is defined as 0.6 times the minimum yield stress of the steel member (0.6fy). This parameter is of utmost significance to ensure the structural integrity and safety of the steel components under axial tension. Therefore, architects and engineers must carefully assess and adhere to the permissible stress limits when designing steel structures to ensure their performance and longevity.