Conceptual Structural Design Methods Of Reinforced Concrete Buildings Rev 2.pptx 5g45k

Conceptual Structural Design Methods of Reinforced Concrete Buildings Dawit Solomon – May, 2014

Contents • • • •

What is conceptual design Some aspects of conceptual design Automated conceptual design example Conclusion

What is Conceptual Design • Conceptual design is an iterative process consisting of a series of generative and evaluative stages that gradually converge on a preferred conceptual solution • At each iteration, concepts are defined in increasing detail by communication and open dialogue with the design team and the Client thereby permitting a more accurate evaluation thus homing into a solution that best suits the function of the building and the Client at large • Some of the items that need to be considered at conceptual design level are as follow:

Conceptual Design • • • • • • • • • •

Functional framing Load transfer Stability Safety Economy Buildability Site Constraints Speed of Construction Aesthetics Fire resistance

Conceptual Design – Functional Framing • Structural design of buildings does not require us to reinvent the wheel of basic structural mechanics and the laws of statics • The function of this frame should also work well with the function and use of the building • Various concrete framing options are available • • • • •

Flat slabs Ribbed slabs Waffle slabs Two-way slabs One-way slabs

• Each frame has its own merit and should be chosen carefully

Conceptual Design – Load Transfer • The designer should workout how the actions on the structure are transferred from the point of application to the ing ground • Generally there are three types of loads that need to be considered: • Vertically acting gravity loads • Lateral loads • Soil loads

Conceptual Design – Safety • The structural engineer should consider how their design impacts on safety during the following stages of the structure’s life: • • • • •

Construction Use Maintenance Refurbishment/alteration Demolition

Conceptual Design – Economy • This aspect of design is very important for designers in Ethiopia as finance for buildings is increasingly getting difficult to secure • A holistic view of the cost should be considered • The choice of the frame will have an effect on the following: • Foundation – A heavier frame will increase the foundation size and rebar • Cladding – Shorter buildings will have less area hence costs less. As cladding costs can amount to 25% of the building costs • Partitions – The same arguments for claddings also applies here

Conceptual Design – Economy • Services – Flat soffit options allow better integration of services.

Conceptual Design – Site Constraints • The location of the site may impose constraints that favor one solution over another. These restraints include: • Proximity of adjustment buildings • Size of the site and working space • Access to the site, e.g. city center sites which could limit access to vehicles • Remoteness • Restrictions on working hours • Effect of site process on neighbors

Conceptual Design – Speed of Construction • The speed of construction and the early commissioning of the building is of great importance both for the Client and the financier of the building. Some of the advantages are as follows: • Building will start generating income • Developer can start loan repayments sooner • The contractor and consultant can allocate resources to different projects sooner • Disruptions to adjacent facilities will be minimized • Quick learning curve for apprentices to name but a few

Conceptual Design – Speed of Construction • The data below is an extract from the Institution of Structural Engineers – Reinforced Concrete Designer’s Manual • It shows speeds of construction for various forms of reinforced concrete frame constructions • The same has been considered when automating the conceptual design process as will be discussed later

Conceptual Design – Fire resistance • Concrete is inherently fire resistant • It is non combustible • Has a slow rate of heat transfer which makes it a highly effective heat barrier • Below is an extract from the Institution of Structural Engineers – Reinforced Concrete Designer’s Manual

Conceptual Design – Automated Conceptual Design • The discussion so far has outlined that conceptual design helps in finding the best solution for a given set of design constraints • It is to the design team’s advantage to carry out this at an early stage in the design process • It is possible to automate most of the items discussed above using a simple spreadsheet. • This is now illustrated in a simple example for a multi-storey building • BIGAR Architecture, Engineering, Urban Design plc CONCEPTUAL DESIGN.xls

Conceptual Design – Conclusion • Conceptual design should be carried out as a team and not as an individual • All disciplines should work together to avoid errors as they all feed off each other • Concepts and drawings should be coordinated and communicated with al of the design team to avoid expensive errors and delay the project • We have established that a holistic approach should be taken when selecting a reinforced concrete frame for a given type of function

Expensive, that’s too expensive

Come on that is not possible

THANK YOU FOR YOUR ATTENTION hmm! I wonder!!

Lets build a floating building