11. Exercises in Computer Aided Building Planning and Drawing (BCV305)

Sketch the reinforcement details for the lintel beam with chejja for 3m wide opening. Size of lintel beam (300x300) mm. Lintel is provided with #5 of 12ϕ bars in tension zone and 2 legged vertical stirrups of 8ϕ at 150 c/c.

Chejja details: projection- 1m; thickness at supports- 110mm and at end- 90mm; main steel provided is 12ϕ @ 150 c/c and distribution steel 10ϕ @ 150 c/c.

This exercise focuses on the reinforcement details of a lintel beam and chejja (a type of eave or overhang). The lintel is designed to span a 3m wide opening, and its dimensions are 300mm by 300mm. In the tensile zone, five 12ϕ bars are used for reinforcement to ensure structural integrity under load. Additionally, stirrups made of 8ϕ bars are placed vertically at intervals of 150mm to add support and stability. The chejja extends 1m outward and has varying thicknesses: 110mm at the supports and 90mm at the ends, with main and distribution steel reinforcements to enhance its strength.

The use of proper bar sizes and spacing ensures that the lintel and chejja can withstand the loads they encounter, while the design details help to guide the construction process, ensuring accuracy and reliability.

Think of the lintel like the frame of a window that needs to bear weight from above. If you were to construct a small table out of wood, you would want to use sturdy wooden planks that could hold various items without bending or breaking. Just like how you would choose thicker, stronger wood for the tabletop, engineers choose specific bars for reinforcement in construction to ensure the safety and durability of structures.

Draw the longitudinal section and cross section of a rectangular RCC beam simply supported Singly Reinforced Beam with the following data: Clear span = 4.8m, Bearing at the supports = 300mm, Width of beam = 300mm, Overall depth of beam = 500mm. Main reinforcement consists of #5 - 20ϕ bars in two layers, Provide #2 - 12ϕ as anchor bars. Stirrups: 2L 8ϕ @ 180 c/c near the supports up to 1.20m and @ 220 c/c in the remaining portion.

This exercise involves creating detailed drawings of a reinforced concrete (RCC) beam, specifically a singly reinforced beam with key dimensions. The clear span of the beam is 4.8 meters, meaning the distance between its supports. The beam has a width of 300mm and an overall depth of 500mm. Main reinforcement is achieved using five 20ϕ bars arranged in two layers to ensure it can carry the load effectively. Additionally, anchor bars of size 12ϕ are incorporated for added grip at the supports. Stirrups made of 8ϕ bars help resist shear forces; their spacing varies from 180mm near the supports to 220mm in the middle of the beam, maintaining strength where it is needed most.

These drawings serve as essential guides for construction, indicating how to place the reinforcing bars correctly to enhance the beam's performance under load.

Imagine loading a bookshelf with heavy books. If the shelf is well-supported and made of thick material, it won’t sag. However, if you used thinner material with weak supports, the shelf might bend or break. Similarly, the design of the RCC beam ensures it can bear heavy loads without failing by using adequate reinforcement at critical points.

Draw a detailed longitudinal section, a cross section near the supports and a section at the middle of the span of a Simply Supported Doubly Reinforced beam for the following data: Clear span = 5.4m, Bearing over the supports = 300mm, Size = 300 x 800 mm. Main reinforcement tensile: #7 - 25ϕ. 4 straight and 3 bent up @ 1400mm from support. Compression reinforcement: #4 – 25ϕ. Spacer bars=25ϕ, Side face reinforcement=#2-12ϕ. Shear reinforcement: 2L - 12ϕ @ 150 c/c for a distance of 1.5m from the support and 2L - 12ϕ@300c/c for remaining middle portion.

In this exercise, we are tasked with illustrating the structure of a doubly reinforced beam, which has reinforcement on both the tension and compression sides. The beam spans a clear distance of 5.4 meters and has a cross-sectional size of 300mm by 800mm. The main tensile reinforcement consists of seven 25ϕ bars, with specific configurations for their placement (four straight bars and three that are bent up). Additionally, compression bars and various stirrups are used to offer comprehensive support against structural stresses. The careful positioning of these reinforcements ensures the beam can manage loads effectively, minimizing the risk of failure due to bending or shear forces.

Consider a suspension bridge, which uses cables both above and below the platform to support the weight of vehicles. The cables above handle tension while those below lend support against compression. Just like that bridge, the doubly reinforced beam uses bars above and below to effectively balance the forces acting on it, preventing any risk of collapse.

Draw longitudinal section and cross section of a cantilever beam from the following data: Clear projection from the face of RCC column = 2500mm. Size of column = 300mm x 300mm. Size of beam at fixed end = 300mm x 300mm. Size of beam at free end = 300mm x150mm. Reinforcement main bars: #5 - 20ϕ with 2 bars curtailed at 1500mm from the support and show the curtailment plan. Compression bars: #3 - 16ϕ. Stirrups: 2L - 6ϕ @ 200 c/c up to 1000mm from support and @ 300 c/c in remaining length.

This exercise focuses on a cantilever beam, which is fixed at one end and free at the other. The clear projection of the beam from the support column is 2500mm, with the column sizing 300mm by 300mm. The beam maintains a consistent size at the fixed end but tapers off to 150mm at the free end. The reinforcement involves main bars of 20ϕ, some of which are curtailed after 1500mm, indicating they are intentionally shortened to manage stresses effectively. Additional reinforcement is used for compression and shear in the form of 16ϕ bars and stirrups arranged at varying spacings along the beam. This design helps ensure that the cantilevered structure can safely support any loads it encounters at the free end.

Think of a diving board that is anchored to a platform. The part of the board that rests on the platform is strong and wide, allowing it to support weight (the fixed end), while the part hanging over the edge is slender (the free end) but needs to be reinforced to prevent it from bending or breaking when someone jumps off. Just like that diving board, the cantilever beam is designed to manage loads effectively while ensuring it remains safe to use.

Draw cross section and plan of one-way roof slab showing the details of reinforcement for the following data: Clear span = 4m, Length of slab = 10m. Thickness of slab = 130mm, Bearing wall = 200mm. Main reinforcement: 12ϕ @ 250 c/c with alternate bars bent up. Distribution reinforcement: 8ϕ @ 200 c/c.

In Exercise 11.5, we design a one-way roof slab that spans a clear distance of 4m and measures 10m in length. Its thickness is 130mm, and it rests on a bearing wall of 200mm in thickness. The main reinforcement consists of 12ϕ bars placed at intervals of 250mm, with some alternately bent up to manage bending moments. Additionally, distribution reinforcement of 8ϕ bars is spaced at 200mm to provide further support across the slab. These reinforcement details are critical for ensuring that the slab can handle the loads from above and any live loads, like people moving on the roof or equipment.

Imagine a large trampoline. The fabric stretches and needs strong springs underneath to support weight. In the case of our slab, the steel reinforcement acts like those springs, ensuring that even as people or objects add weight, the slab can flex and stable without collapsing.

One-way continuous slab has been provided for a hall of clear dimensions 8mx14.25 m. the slab is supported on RCC beams. The following details are given. C/C distance of supporting beams=3.5m, Column dimensions on which beam rest=250mmx500mm, C/s of beams=250mmx600mm, Slab thickness=150mm. Main positive reinforcement at the end and interior panels=10ϕ @120 c/c. Main negative reinforcement at all supports=10ϕ @120 c/c. Distribution steel =8ϕ@ 250 c/c. Draw cross section and plan showing the details of reinforcement (Bottom & top).

In this exercise, we study a one-way continuous slab that spans a clear dimension of 8m by 14.25m and is supported by RCC beams. The center-to-center distance between the beams is specified as 3.5m, and the slab itself has a thickness of 150mm. Positive reinforcement of size 10ϕ is placed at 120mm intervals across the ends and interior panels to manage bending. Notably, negative reinforcement, which prevents sagging at supports, is also implemented at the same spacing. Moreover, distribution steel of 8ϕ is used at wider intervals of 250mm for added support. Such meticulous detailing ensures that the slab has the necessary strength and stability under various load conditions.

Think of a large flat table supported by multiple legs. If you only have legs at the corners, the center might sag. To prevent this, you add more legs beneath the table to give it strength and keep it flat. The continuous slab reinforcement does something similar by adding steel that supports the underside, ensuring it doesn’t sag or break under weight.

A simply supported two-way slab is supported on all sides by using 230mm thick wall. The dimension of the two-way slab is 3m x 4m (Clear). Following are the reinforcement details: Along shorter span: 10ϕ @125 c/c, Along longer span: 10ϕ @150 c/c, Negative steel for shorter span: 10ϕ @250 c/c, Negative steel for longer span: 10ϕ @300 c/c, Alternate bars are cranked, Corner mats are 8ϕ @150 c/c along shorter span and 8ϕ @200 c/c along long span. Thickness of slab is 150mm. Draw plan showing reinforcement and cross section along longer & shorter span.

This exercise centers around the design of a simply supported two-way slab. Dimensions of the slab are set at 3m by 4m, resting on a 230mm thick wall all around. Reinforcement details vary depending on the span: along the shorter span, 10ϕ bars are placed at 125mm intervals, and along the longer span, they are spaced at 150mm. Special attention is given to negative steel reinforcement at the supports to counteract sagging, which uses additional bars at wider spacing. The thickness of the slab is standardized at 150mm. By carefully planning and illustrating the reinforcement layout, engineers can work to ensure the slab performs well under various loading conditions.

Think of a pizza crust that can only be supported from the edges. If it’s not strong enough, the middle part may collapse when loaded with toppings. By reinforcing the crust (or slab) with steel bars, we prevent the risk of sagging or breaking, not unlike how we ensure our pizza crust holds all its delicious toppings without falling apart.

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