El origen del poncho

(1) Colours, whether they are applied or natural, play a major role in aesthetics. Colours can be applied to structure surfaces by painting or staining, or through the selection of appropriate constituents such as various aggregates, cements and admixtures as integrated into concrete. The greyish colour of concrete is by itself a relatively unobtrusive tone. Since being unobtrusive helps to make a bridge more visually acceptable, structural concrete shall not be coloured under normal circumstances. This has the added benefit of avoiding unnecessary maintenance commitment since painting on concrete requires regular maintenance.

(2) Particular attention shall be paid on choice of colour. Earth tones are known to perform better, while striking strong colours shall be avoided since they are known to be more easily broken down by sunlight and environment. Colours can be used to strengthen or lessen the visual effects of individual members. Warm colours (red, yellow, brown, etc) will emphasize the size of forms while cool colours (blue, green, purple, etc) can reduce the visual importance of elements. Bright colours make bold startling aggressive statements and shall be used with caution, while soft colours will easily blend into the

surrounding environment. Maintenance issue shall be addressed for accidental wearing, e.g. vehicle impacts on barriers, etc.

(3) Colour can either be used to blend a structure with its surroundings or to create a contrast between man-made objects and nature. While a bridge of natural concrete colour will have slight deviations in the shade of grey concrete for various components (due to different concrete mixes , etc), it tends to be the human perception that a bridge with applied colour will have a better look.

(4) Nevertheless, the application of colours in a structural design composition is considered to be an important tool in achieving both functional and environmental enhancement. It is particularly useful and often essential where associated human factors need to be incorporated. For instance, interior surfaces shall be „inviting‟, „comfortable‟ and „safe‟ instead of „forbidding‟, „bleak‟ and „vulnerable‟. Surfaces shall also be „neat‟, „warm‟ and „inspiring‟ instead of „messy‟, „cold‟ and „depressing‟. If these factors fail to be properly addressed, structures are likely to detract from, rather than to contribute to, the quality of an environment into which they are introduced. Use of architectural cladding can be considered for applications at certain prestigious locations, with due consideration to longevity and maintenance issues.

(5) The most difficult part of developing a functional as well as pleasing chromatic design is the management and control of subjectivity or personal likes and dislikes in the selection of colours and finishing materials. It is therefore essential to the success of a scheme to adopt an objective approach in the lead-up to its design.

(6) To this end, three critical aspects of a project are identified which call for action in step with normal design development stages, as follows :

(a) The Chromatic ‘Mood’ of a District and/or Local Environment. This „mood‟ is catalogued as part of the design investigation stage by recording the chromatic composition of the environment, bringing together all visible colours exactly as they are perceived by observation. From this record, the designer determines whether there is something missing from the chromatic make-up of the area that shall perhaps be introduced to stimulate interest or build up local character. (b) Primary and Secondary Functions of a Structure. Primary functions include the

purposes for building it whereas secondary functions include any perceived purposes arising from its location on a site and in a district such as pinpointing the „genus loci‟, traffic route and direction of travel. The detailed analysis of all functions determines the range of human factors to be considered, which will be much wider for structures designed for pedestrian use than for vehicular movement.

(c) The Design of the Structure Itself. The basic structural form represents the solution to a number of identified engineering problems within a framework of known site constraints. It may not in itself fulfil all the requirements imposed by its functions. Certain elements may need to be highlighted or obscured to either

adjusting visual quality to serve attendant functions using the chromatic design tool.

(7) Only after taking adequate stock of these elements is a designer equipped to develop a practical design theme and consider a palette of colours from the natural colour spectrum which would best serve to achieve his design objectives. Figure 15.28 shows an example.

(8) For chromatic design, one of the most comprehensive codes available today is the Swedish Standard No. SS 019102, which adopts a Natural Colour System (N.C.S.) for identification, selection and specification of the complete range of visible colours. A comparable colour identification system in common use is the Pantone Colour System. However, no system will adequately address in every detail finishing aspects such as matt, high gloss, metallic or textured, etc, making it necessary at times to refer to manufacturers‟ publications such as charts, product specifications and samples in order to complete a scheme design.

(9) Long term colours cannot be forecasted precisely on the drawing board. Appearance will vary with a number of factors including material characteristics (absorption, roughness, metallic or non-metallic, etc). The designer shall always consider the need for controlled pre-construction experiments on site in the actual lighting conditions (not merely fixed samples for approval) so that trial panels can be viewed in order to select the most suitable material.

(10) In the final analysis, the success of a design will be contingent upon the appropriateness of its theme, its interpretation in the overall layout and the degree to which objectives have been met in the detailed treatment of individual elements.