12.1.1. Exercise: 12.1

Draw plan and sectional elevation of RCC dog legged staircase for an office building which measures 3m x 5.5m.

In this exercise, we are tasked to design an RCC (Reinforced Cement Concrete) dog-legged staircase for a specified office building. The staircase must fit within a rectangular area measuring 3 meters by 5.5 meters. This means that the staircase's horizontal setup must perfectly align within these dimensions, considering both the plan view and the sectional elevation.

Imagine trying to fit a puzzle piece into a specific space. Just like with the staircase, every piece needs to fit perfectly within the provided dimensions for the entire picture to come together.

The vertical distance between the floor is 3.3m (including landing).

The height of the staircase is crucial for determining the number of steps needed. In this case, the total vertical distance between two floors is 3.3 meters, which includes the landing surface where someone would step before continuing up or down the staircase. Understanding this height helps in calculating the height of each step.

Think about a tall building where each floor is like a step on a stairway. To go from one floor to the next, you need to climb a certain height. In buildings, just like in traditional staircases, you need to consider landings where people can catch their breath before going up another set.

Thickness of the floor slab is 150mm. Provide steps with tread of 300mm and rise of 150mm.

The design specifies that the steps must have specific dimensions: the tread (the part you step on) is 300mm wide and the rise (the height of each step) is 150mm. Additionally, the thickness of the floor slab that supports the staircase is set at 150mm. These measurements are important for ensuring comfort and safety while using the staircase.

Consider how a good pair of stairs should feel while walking. If the steps are too high or too narrow, it can be uncomfortable. A good design strikes a balance, just like a well-tailored shoe fits the foot perfectly.

Thickness of waist slab and landing slab is 150mm. Width of stair is 1.5m.

The waist slab, which is part of the staircase that connects the steps, and the landing slab, which is the flat part at the top and bottom of the staircase, both have a thickness of 150mm. The width of the staircase must be 1.5 meters, ensuring that it is wide enough for individuals to ascend and descend comfortably, especially in an office setting where foot traffic may be frequent.

Think of the staircase like a highway. A wider highway (the stair width) can accommodate more cars (people), and solid construction (the thickness of the slabs) ensures that the highway can handle the traffic without crumbling.

Reinforcement details: main steel: 10ϕ@125c/c spacing and distribution: 8ϕ@ 250 c/c spacing.

The construction of the staircase requires reinforcement to ensure it can bear the load and withstand use over time. The main reinforcement steel bars have a diameter of 10mm, and these bars are spaced 125mm apart. Additionally, there are distribution bars with a diameter of 8mm spaced 250mm apart. The spacing and sizing of these bars play a crucial role in the structural integrity of the staircase.

Think of the reinforcement like the bones in your body. Just as bones provide support and structure, the steel bars in a staircase provide the strength necessary to hold up the steps and ensure they don’t collapse under weight.

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