COMMERCIAL
Leadway
Description: Six (6) story ultra-modern office building; parking at the basement and ground floor level.
Scope of Work: Structural and Civil Works Design & Supervision
Floor systems adopted were predominantly 300mm thick 2 way spanning ribbed slab with Styrofoam infill on the office floors and one way spanning ribs in the vehicle ramp linking the ground and basement levels. This vehicle ramp floor system spans in the direction of travel to curb agitations/vibrations and ensure smooth travel along the ramp. Robust reinforced columns and walls were deployed to provide adequate gravitational and lateral load resistance and stability.
The building was founded on 300 mm thick raft accompanied by 750 mm x 750 mm ground beams. Other buildings in this project include a crèche building for members of staff, a gate house constructed with composite floor systems /structural steel frame and other ancillary buildings.
During construction, modifications such as increase of column geometry to receive extra loads, provision of a storm water collection system in the basement by lowering a raft slab panel occurred to suit client’s requirements. All through the process of said modifications, active soil pressure beneath foundation was kept < 50 kN/m2.
God's Grace House
Description: 6 suspended floors + Roof - Office development
Scope of Work: Structural/Civil Works Design & Supervision (Construction On-going)
The structure is of simple but very effective/efficient structural system (rigid frame) founded on 150 mm diameter micro piles terminating at 34 m below the ground. Every pile in a group were tied together with pile caps and a pile group to another with ground beams to prevent subsidence and differential settlement. The choice of this foundation system arose due to the very poor soil conditions of the area.
The 1st floor consists of considerably long spanning deep beams (minimum of 1 m depth by 0.3 m wide)- as long as 16.42 m serving as transfer structures for the loads from the 2nd floor to roof. The long span beams in the 1st floor were used so as to keep a column free space and allow movement of cars in the car park area of the ground floor. 300 mm thick concealed beams were adopted on the 2nd to 5th floors to support 300 mm thick two way spanning ribbed slabs constructed using lightweight fire rated Styrofoam blocks as slab forms. This slab/concealed beam arrangement helped reduce to a great extent the weight of the structure (approximately 65% per m2 savings in concrete weight). All Columns and the lift walls were designed to serve as load transfer members and curb vertical displacements owing to wind forces at high levels of structure.
PTL Towers
Description: Ground + 4 suspended floors office building
Scope of Work: Structural Design & Supervision
The structural system deployed was rigid frame founded on very firm soil strata via conventional Pad bases and strips. Multiple transfer structures exist on the first floor as columns change positions to accommodate the open office plan. Solid slab floor system was adopted for 1st to 3rd floors while composite floor system (concrete topping on steel plate) was adopted on the 4th floor as it was a later addition due to client's request.
AA Holdings
Description: Two (2) Storey Purpose-built office building + Swimming pool.
Location: Oba Elegushi Road, Ikoyi, Lagos
Scope of Work: Structural Design & Supervision
A challenging yet interesting structure that features series of overhangs on the 1st floor with the longest being 6.24m.
Floor systems adopted were predominantly 300mm thick 2 way spanning ribbed slab (2.7m centres) and conventional solid slabs.
The reinforced columns alongside a one storey deep concrete truss provide adequate gravitational and lateral stability whilst taking the loads to the
coventional raft foundation sized to suite an allowable 40kN/Sqm soil bearing capacity.
Idado
Description: Dual wing multipurpose office complex consisting 3 suspended levels.
Scope of Work: Structural Design & Supervision
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A flat plate floor system was required as par client’s request to allow free passage of mechanical and electrical services in the ceiling and ultimately maximizing head room. As such, 300 mm thick - 2 way spanning ribs were adopted. The floor system proved lighter in weight and cheaper per m2 of concrete cost keeping the project within cost band. The lift walls were however unable to provide adequate resistance to lateral forces as they situated on one side of the leeward face of the structure. As such, the robust columns were called into action for both gravitational and lateral load resistance. The foundation system used was raft with ground beams for soil confinement.
Omida Market
Description: 4 suspended floor ultra-modern shopping mall for the Ogun State Government.
Scope of Work: Structural Design & Supervision
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Structural system adopted was rigid frame, floor slab system adopted was 200 mm thick solid slabs and 600 x 230 mm drop beams. The project featured various cantilever slabs with up/down stand facials to serve as walkways round the building perimeter as well as give an artistic impression. The roof system was a combination of reinforced concrete decks in water tank areas and structural steel trusses with DanpalonTM to allow light through the building atrium. Conventional pad bases (with pedestals to resist punching) support the superstructure while strips support the ground floor.
Saro
Description: 1 storey office building, pavement and drainage systems in Lagos; 1 storey admin building, 4500 m2 Container terminal, 7000 m2 warehouse, Weigh bridge, rigid pavement (i.e. hard standings) and drainage systems in Ilesha.
Scope of Work: Structural design/Civil Works Design & Supervision
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The peculiarity of the Lagos project was the unconventional approach to tackle inadequacy of the soil to receive the proposed structures (building and pavement). The soft clay within topmost 1000mm layer of soil was removed and replaced with well compacted river drained sand to accommodate shallow footings of strip and raft respectively in the ware house and office buildings. 25-ton capacity rollers were deployed to compact in-place soil. Greatest challenge here was recorded in the undue time lost as the 25-ton capacity rollers weren’t able to compact and attain Maximum dry density more quickly. This we got round much better by deploying 5 tons vibratory plate compactors to the works and reducing successive layers of sand to 75 - 100mm thick with number of passes not exceeding 4 to 5 times.