There is a need for structural flexibility in buildings, i.e. design and construction of adaptable buildings which can be modified time to time based on requirements. This articles provides information on how flexibility or adaptability in buildings can be adopted, their types and why it is required.
Prologue: The word flexibility has been explained in terms of building quality construction as well as flexibility in structural mechanics.
Stages of Structural flexibility in buildingsStructural flexibility of buildings has following two stages:
- The design stage: variability in the composition and the use of material;
- The user stage: flexibility to adjust the composition and the applied building components to the changing demands and/or wishes of the same or varying users while in use.
Why Structural flexibility in buildings or adaptable buildings required?Considering in structural level, flexibility in the user stage may be translated into possible adaptability of the floors to higher working loads (extreme live load) and the realization of recess for stairwells, lift shafts or pipes and ducts. Urban areas and building have undergone redevelopment when we compare them with past centuries. These were undergoing degeneration before they were met with a redevelopment. Industrial areas with warehouses were transformed into housing or as office spots. As per the past and present record of buildings, many were demolished, but some of them were refurbished and granted a second life of functionality. It is based on the analysis that some of the buildings were more prone to demolishment, but somewhere more suitable for redevelopment. Something that must be noted is that most of the building that had undergone redevelopment was not constructed during their first construction, about the possibilities of remaking it. It was not foreseen. It was not designed to undergo functional changes. It's just a coincidence and favorable factor that made it possible to undergo a refurbishment even though this objective was not foreseen.
Building Service Life ExtensionThere are certain aspects that would be considered favorable for a second functional working life, which is mentioned below
- Location- Building location quality marks essential criteria that make an engineer to fix his decision in renovating the building.
- Quality of the building and the structural components technically
- Historical value and its architectural quality
- Economy- The aspects of the economy which includes the cost of refurbishment compared against the cost required for demolishing as well as rebuilding and of course the returns in form of profit as service or finance.
- The approval of local urban planning rules and the building regulations
- Building owner or authorities vision.
- Sustainability keeping in mind the environments aspects like air, water pollution, soil conditions etc.
- Space Plan (Walls for partition)
- Access (Lifts, corridors, stairs)
- Service Elements (Pipes, cables building services)
- Envelope (Base, roof, facades)
- Structural elements (Columns, floors, load bearing walls etc.)
Fig.: Adaptable Building Layers
Structural Flexibility of Buildings Under earthquakeThe structural flexibility can be defined as the property of the building structure to accommodate any changes in use by providing sufficient space as well as load-carrying capacity and letting changes in one more of the building layers without the requirement to change the structure itself.
Oscillation of buildings with flexibilityWhen the ground shakes, the building base can move with the ground movement acting flexible nature. This would cause different building parts to move back and forth. If the structure was a rigid, all the elements would have moved together. A mixture of sinusoidal waves of different frequencies ranging from short to long combines to form an earthquake ground motion. Period of the earthquake wave is the time taken for one complete cycle of motion. What intensity will the earthquake strike the building depend on upon different factors:
- Magnitude of earthquake
- Epicenter distance
- Type of ground the earthquake waves traveled