- Feb 2011
I'm not saying the Pantheon is better than other buildings in everyway, only that its more structurally sophisticated. The fact that East Asian wooden architecture allows for a 10 meters or so gap between supporting columns falls short in comparison. Even considering the huge roofs and its projections.
Long gaps between supporting columns was what the Romans were aiming for. You are still using Roman standards to judge non-Roman buildings. Very long eaves, multi-eaves for every level, maximizing window space, is not something the Romans aimed for, but others did.
"The Chinese Hall Building has not changed greatly since the Han, essentially being a three-part structure comprising a sturdy platform on which a timber frame supports a roof that visually (and physically) dominates the structure. Much of the weight of the roof is in its ceramics, and this can be very significant. For example, the roof of the Taihedian, a principal hall in the Forbidden City, weighs upwards of 2000 tons. On a floor plan area of approximately 2000 square metres this average load of 1000 kg per square metre, equivalent to between 30 to 40 tons per square metre at the base of each of its 72 columns, is impressive by any standards. The sturdiness of such buildings owes much to the design of their complex timber frames, which have been much studied by architectural historians, as well as to the static loading of their ceramic content." - Colours and Contrast: Ceramic Traditions in Chinese Architecture, By Clarence Eng, pg 26
Also from the same source, pg 27-29
"The strength of the timber frame is helped by its parts being almost entirely under compression, and by its use of bracket sets, dougong, which brace the structure and distribute loads along the length of horizontal members. This is best seen from drawings, which also illustrate the quality and detail of structural research on timber frames. Overhanging roof eaves, supported by beams cantilevered outwards from the outer columns act as a canopy to protect the walls and foundations and also regulate solar gain by admitting low-angled winter sunlight to the interior but providing cool shade in the summer.
Above the eaves-height the complex woodwork in the roof-space serves a number of functions. It braces the supporting columns and distributes the roof loading between them, and it also presents the main ridge and multiple purlins of the roof at appropriate relative heights to give the external surface the desired curvature, which is often concave but can also be convex.
Below eaves level the structure relies on the supporting strength of its main upraights, which for the most prestigious buildings were traditionally hard wood tree-trunks cut in the round. The prodigious weight of the roof of the Taihedian in the Forbidden City is carried on 72 pillars, most of it on the 24 main columns inside its vast ceremonial area. As noted by Edward Farmer and Yu zhuoyun, the process of finding and transporting by water such hardwood trunks from south-west China was in itself a major undertaking, involving a journey of up to four years, and further straining an already-congested Grand Canal.
The skilled construction of the timber frame, the 'major carpentry' , was critical for the integrity of the structure. The durability of a hall building comes from its structure being strong but not rigid. This allows energy to be dissipated by friction within its complex dry joints, enabling the structure to absorb shocks from wind gusts or earthquakes. This will be discussed further in Chapter 9.
Not only does the absense of load-bearing walls in the traditional hall building allow for a flexible floor plan, but the structure is sufficiently resilient even for columns to be omitted or removed to adjust thespace available for audience or ritual. A further practical feature is that it is easy to make localised repairs as required. Less conveniently for historians, this sometimes complicates the dating of different parts of a building. Occasionally, circumstances require that radical repairs involve stripping the building back to its main framework timbers before restoration, as seen at the Guozijian, Beijing.
However, it will be suggested in Chapter 3 that the more normal custom of making localised repairs, together with the recycling of re-usable parts may have preserved the continuity of original tiling colour schemes.
Even when radical restoration is undertaken, as for instance during 2006 renovations at the Gugong in Beijing, the practice is still clearly to re-use serviceable parts wherever possible, so it can probably be safely assumed that the fabric of nearly all buildings is a mixture of original parts and later replacements."
That's about the span of the Tadaoji.Both use wooden ceilings that cover very big spans, I believe between 20 and 30 meters. But they have the "inconvinience" of having brick/stone walls.