CPCCBC4011B Commercial Low Rise Constructions: RC Frame Building

Footing System:

This building uses a pad foundation system as the building’s footing. This was the answer given upon inquiry ideally one would be able to tell by either the boring equipment on the site that is employed in the boring of holes in the ground for concreting when the pad footing is being installed and subsequently the beam member. This footing system is especially used by the moment resisting and concrete frame structures for the practical aspect of it facilitating load transfer by the members only into the ground. It can work with most wall systems including but not limited to masonry walls, concrete walls (in situ and precast), steel systems and even timber walls. This system is also proven to work in various and varying soil conditions with the benefit of it being able to resist the different imposed conditions e.g. settling, swelling, water logging etc. better in relation to other systems.

The footing system is illustrated below.

Figure 2: Pad footing foundation

Structural Systems:

• The structural framework is shown in the photograph below.

Figure 3: Structural framework.

• The section shows the meeting point between a column, beam and slab. This is the frame that supports the building loads and the only other section yet to be shown is the foundation. The floor load is carried by the floor slab and could either be dead or live. It is then transferred to the beams which take this load to the column. The columns then transfer the loads to the foundation which then transfers the load to the ground.
• The building load is transferred as shown below in the following figures:

Figure 4: Concrete frame load path

Figure 5: Beam to column connection.

Flooring System:

This system uses a concrete flooring system for the slab. This is a system where a screed floor rests on a reinforced concrete slab which, in our case, rests on a system of beams that then transfer the load to the piers in the ground. The reinforced concrete slab system is indicated below.

• Construction sequence of the floor slab is:
  1. The slab formwork is placed after the footing system is concreted.
  2. The ground level slab concrete is batched and placed and after it cures the concrete column formwork is then erected.
  3. The concrete columns are then batched and placed and cured for a period of time.
  4. After curing of columns, the beam formwork is erected.
  5. The beam rebars are then fixed together.
  6. The slab formwork is erected.
  7. A waterproof membrane is placed under the reinforcement on the floor of the beam and slab formwork.
  8. Beam and slab rebars are then fixed together in place.
  9. The concrete for the slab and beams is then batched and placed and cured.
• The slab reinforcement to be used is bar size, N20 which will span 6m from end to end.

Wall Systems:

• The wall system used is photographed below while the details not clearly seen are shown below it:

Figure 6: Block and brick masonry wall on site.

Figure 7: Block and brick masonry wall sketch.

• The first step in wall system erection is setting out and staking to provide locations of the walls on the ground.
• As the blocks, will lie on the concrete floor slab, set up a foundation for the concrete black wall that is at least 100mm wider than the masonry block.
• Wet the foundation surface and apply a 25mm thick layer of mortar.
• Lay the first brick course and check for vertical and horizontal alignment using a plumb bob and spirit level respectively.
• Speed the mortar again on the sides and scrape off the excess using a trowel.
• Add another layer of mortar on top of the first course, 25mm thick.
• Place the second course and confirm both vertical and horizontal alignment.
• After every three courses, add an inch-wide, thin steel metal strip and repeat the last three steps till the desired height.

Services:

• There are a variety of methods used by builders and designers in disposing of storm water in a structure. This is very important as this storm water can ruin the property, decreasing its value, lead to spread of diseases and cause the aesthetic degradation of the property. The designers and contractors can use a variety of methods for this dissipation which include:
  • Guttering: in this system, a series of shallow sloping channels is installed along the edge of the roof and these direct the storm water to the downpipes for either disposal or storage.
  • Pipes: these are conduits in the form cylindrical tubes that carry fluids or service connection wires. In the case of storm water disposal, they are channels that guide water either to a storage or sewer system for disposal. They can be either downpipes, directing water to the sewer or storage system from the roof of the house or underground pipes that transport water in the sewer to an offsite drainage location.
  • Ponding areas: when water collects on an impermeable layer either on the ground or on a flat roof system, it forms a little puddle or pond. This is called ponding. It is usually unwanted and should be avoided as much as possible.
  • Detention/retention tanks: when a storm event exceeds produces an amount of water that exceeds the expected or designed capacity or a sewer system has a low capacity accommodating an amount of water much less than the storm water capacity, a storage or retention tank is provided. These store the water and release them in less volumes than they would flow in order to allow the sewer to drain. Without these, all the water would flow directly to the sewer causing blockage and therefore overflowing onto the street.
• The services provided to this building are electrical, mechanical and plumbing. The electrical system consists of conduits for power transmission, internet and communication. The mechanical include the air conditioning system while the plumbing includes the water supply and the gas supply. The services supplied to the building are shown below.

Figure 8: Building services. Source: https://structuretech1.com/csst/

• The main fire detection system for this system is a series of fire detectors installed in every corridor and room. These are basically fall under both active and passive as they detect the fire as a result of an action i.e. smoke rising up to the detectors and act without requiring any human input making them passive too. However, the system uses an active and passive protection system as it has more than four storeys. In the active component, it uses both fire extinguishers and a fire hydrant and hose pipe system. These are active as they require human input in their operation. The passive fire protection systems in this case are fire resistant walls, doorways and staircases. These are put in place to allow occupants of the building enough time to vacate the structure before the arrival of the fire brigade.

Roof System:

• The roofing system used in this building is a steep sloped hip and valley system of roofing. This is where the roof has ridges in between adjacent crests unlike where there is just one crest and no valley.

Figure 9: Hip and Valley roof. Source: https://www.kdneill.com/?lightbox=image1ab5

• The system is detailed below. The main bracing elements are the strut trusses indicated in the diagram below.

Figure 10: Roofing system.

• The roof cladding system used is shingled cladding.
• The gutter section is illustrated below.

Figure 11: Gutter sketch.

Bibliography:

Al-Chaar, G., Issa, M. and Sweeney, S., 2002. Behavior of masonry-infilled nonductile reinforced concrete frames. Journal of Structural Engineering, 128(8), pp.1055-1063.

Hendry, E.A., 2001. Masonry walls: materials and construction. Construction and Building materials, 15(8), pp.323-330.

Nilson, A., 1997. Design of concrete structures (No. 12th Edition).