Conceptual building design
The following lists provide an aide memoir for a number of the constraints, parameters and performance requirements. They should not be regarded as being comprehensive and the reader is invited to add other items that experience has shown need to be added.
Typical needs • Overall dimensions • Stairs, doors and windows • Façade treatment and appearance • Vertical transport • Distribution of services • Clearance heights and floor spaces • Use and architectural layout
Stated constraints are those listed in the Task Statement • Available site dimensions • Column spacing • Floor heights • Minimum clear spans • Soil conditions • Wind speed • Imposed loading
Unstated constraints are those not mentioned in the Task Statement either through ignorance or because they are taken for granted
Architectural constraints • Column spacing • Stairs, doors, windows and lifts • Clear floor-to-ceiling height • Structural material • Statutory Regulations • Fire resistance • Roof and drainage details • Façade treatment • Services (H&V, lighting, water and drainage) • Non-structural materials
Building construction constraints • Fast-build programme • Access to site • Adjacent buildings • Ground conditions • Foundation and basement requirements • Related to concrete construction: mix-on-site or ready mixed, transport, reinforcement, falsework and formwork, precast concrete, working sequence • Floor systems • Construction equipment • Labour skills
Building material constraints • Ability to cope with movement: structural movement; intrinsic movement (i.e. shrinkage);temperature (both diurnal and seasonal) • Availability (reference countries outside the UK) • Durability: maintenance; repair; replacement • Appearance: applied finishes; manufactured finishes; weathering • Buildability: prefabrication; cast-on-site; method of attachment; connections
Structural engineering and safety constraints • Statutory regulations and Codes of Practice • Structural materials • Strength, stiffness, fatigue, etc. • Construction method and sequence • Possibility of overload • Connections • Foundations • Fire resistance • Watertightness, durability and deterioration • Column spacing and floor system • Stability, bracing and shear walls • Future extensions or change of use • Distribution of services • Architectural layout
Performance requirements • Structural safety: safely buildable, safe in use, safely removed after use; cracking; records for future alterations and/or extensions • Serviceability (all relative to the intended service life): fire resistance; thermal insulation; acoustic insulation; durability and cracking; movement and vibration - load induced and/or inherent to materials • Maintenance: Preserve the performance – cracking; records of condition, repairs made, replacements • Economic construction: ‘value for money’; Initial cost; cost in use • Structure: support external envelope; support the finishes; support the services; support the people and contents • Enclosure: non-loadbearing internal walls and partitions; non-loadbearing external walls and windows • Finishes: insulation: weatherproofing; wearing surfaces; superficial appearance, inside and outside • Services: water supply and storage; heating and cooling, ventilation; prevention of excessive heating or cooling; artificial light; power, lifts, etc.; waste disposal; fire escape; rainwater disposal • Basements: watertightness, sumps and pumping; appearance, lighting and ventilation; access – general and emergency
The features of a feasible scheme will be dictated by a number of analytical, material and constructional parameters
Analytical parameters • The perception of the loads: imposed, imposed dead, and self-weight or dead loads. The type of load: uniform, point, moving, cyclic, etc. • The characteristics of the structural materials: strengths in tension, compression, shear, stiffness of the material (E value), weights. Effects of temperature, moisture and sustained loading • Span, height and support conditions: one-way or two-way spanning, simple or continuous spans; combined stresses such as with columns where the compression can be combined with uni-axial or biaxial bending; hinged, sliding or fixed support
Material parameters • Ability to cope with structural and non-structural movements • Availability (restricted in some countries by cost, custom or lack of appropriate skills) • Appearance (as required by client of architect, or as available from the method of construction) • Durability (influenced by the environment, façade treatment and appearance required) • Maintenance (functions of the physical nature of the materials, the environment, expected economic life of the subject, architectural finishes, safety and seviceability constraints) • Method of assembly (influenced by the physical nature of the materials, local customs and skills, available machinery, transport and programme) Constructional parameters • The construction method shall be safe and stable and may not endanger humans nor adjacent property, roads or services • Short- and long-term support during demolition, including underpinning and shoring • Control of dust and noise levels • Support to sides of excavations • Control of groundwater • Transport and placing of materials • Suitability of mechanical plant and equipment (e.g. scaffolding) • Protection of the public, and protection of the amenity and environment • Programme • Cost • Stability during construction • Early weathertightness • Attention to the special sequence-dependent construction
Technology identification • Framed system: slabs and beams; columns and walls; cantilevers; girders and Vierendeel girders; portals; bracing • Trussed system: trusses; space frames; cable stays; geodesic domes • Funicular systems: catenary cable; tents; pneumatics; arches; vaults • Surface structures: shells; folded plates • Principal axis: transverse; longitudinal; bi-axial (square, circle) • Material: steel (rolled sections; traditional site bolted; welded fabrication; site-welded connections); concrete (in situ; precast; pre- or post-tensioned); timber; masonry (stone; brick; concrete block); other (alloys; synthetics; glass); composites • Foundation: traditional strip footing; pad or pier with groundbeams; pile, caisson, barrette; combined base; raft, cellular raft; basement • Stability: gravity structure; bracing; shear walls, core, hull-core; rigid joint; anchors • Multi-storey: From ground to roof or full-height frame; raised on pillotis and then full-height frame; Fullheight frame with alternative groups of floors (villages) and penetrations (gardens); Core – roof frame – hangers, beams and slabs • Floor systems: concrete (beam and slab construction; flat slabs and flat plates; waffle and ribbed slabs; prestressed slabs; precast units; patented systems); steel (metal decking with concrete topping; steel beams with composite concrete slab; steel beams with precast concrete slab); timber (beam, joist and floor boards) • Special issues: retaining walls; waterproofing of basements; water-containing structures; earthquake resisting structures.