Evaluation of geometrical characteristics of Korean pagodas

Transcription

1 Evaluaton of geometrcal characterstcs of Korean pagodas *Fahmeh Yavartanoo 1) and Thomas Kang 2) 1), 2) Department of Archtecture and Archtectural Engneerng, Seoul Natonal Unversty, Seoul 08826, Korea 2) ABSTRACT One of the most popular monuments n Korean archtectural hertage s mult-story stone pagoda. Ths study ndcates detaled descrpton and geometrcal proportons of Korean pagodas. To evaluate geometrcal characterstcs of Korean pagodas, several cases were nvestgated and fnally 60 of them wth data that are more accessble were chosen. The pagodas are classfed nto dfferent groups such as 3-story, 5-story and 7- story pagodas and dfferent materals such as stone, wood and brck, though most of them are 3-story and stone monuments. The structure of pagodas s dvded nto four parts to evaluate geometrcal features: base sty lobate, body, roof and head. Ths study has been focused on two sectons, body and roof n detal. Usng exstng database, they were modelled n AutoCAD software to compare ther proportons more accurately. Then the heght, length and wdth of body part as well as the length and wdth of roof were nvestgated. Accordng to the results, t s found that Pagoda structure follows a certan pattern wth specfc geometrcal proportons. 1. INTRODUCTION The purpose of ths paper s to defne dfferent structural forms of pagodas, whch are one form of stupas, and to evaluate proportons of these hstorcal monuments n Korean ancent archtecture. In the ffth century BCE, the hstorc Buddha Sakyamun ded and was cremated, and the sarra found n hs ashes were dvded nto eght portons. Stupas, whch are dome-lke structures smlar to pre-buddhst bural mounds n Northern Inda, were bult over these relcs. Stupas are defned as a symbol of nsghtful. Wth lookng at stupa n clockwse drecton t can be seen a respect for what the stupa contans and ndcates (represents). The geometrc and shape of the stupa was changed wth spreadng Buddhsm throughout all Asa. In Chna, Korea, and Japan, the shape had been changed to mult-storeyed towers. The stores of the towers, or pagodas, became smaller n sze wth each story, and represented the branches of the tree of lfe and the 1) Ph.D. Student 2) Assocate Professor

2 terraces of the mythcal mountan. Wth the passng of tme (year by year), the pagoda changed step by step n usng from keepng Buddha's actual body parts buldng to a monument whch beleved to be symbolc of Buddha and a place of worshp. In Inda the frst pagoda was created lke a sem-sphercal tomb. In followng eras, sty lobate (a flat sdewalk) was added to the base as a functon of supportng and a sangryun (a long cylndrcal metal ornament) was added to the pagoda's top and also a stone ralng was added to surround the structure wth beautful form n desgn features, end n the pagoda shape most famlar these days (Chodzn and Kohn, 1998; Jo, 1995; Khan,1985). 2. SOUTH KOREA A SOURCE OF STONE PAGODAS 2.1 Hstorc Characterzaton of Korean Pagodas People s hstory, lfe, relgon, etc. can be found n archtectural hertages as a part of human culture. So, a socety has an oblgaton n preservng ths hertage safely to transfer t to next generatons (Park et al., 2014). A pagoda (called "tap" n Korean), whch s a mult-story structure generally found at Buddhst temples, s consdered the grave of Buddha. In chna wth enterng Buddhsm, the Indan-style sem-sphercal tomb format was changed wth a wooden pagoda n the shape of a pavlon. The Chnese style has then mgrated to Korea and remaned as a hghly popular pagoda durng the Three Kngdoms Perod. Koreans used stone and created unque and unparalleled pagoda n the world whch can ntroduce Korean hstory, culture, and relgon (Park et al., 2014). 2.2 Structural Characterzaton of Korean Pagodas To protect archtectural hertages, one must consder natural dsasters and hazards caused by socal and envronmental changes because most of them are always exposed outsde. Even so, many masonry structures n archtectural hertages have kept ther structures ntact for a long tme despte numerous hstorc records of earthquakes. A great number of stone cultural hertages are well preserved n Korea, ncludng unrenforced masonry structures that are seemngly weak durng earthquakes (Antque Alve, 2015). 2.3 Korean Pagodas Classfcaton Materal Classfcaton In Inda by usng earth, then n Chna wood, pagodas were bult as mult-story structures, whch were spread to the three Kngdoms of Korea, and then Japan. The pagoda tradton was dverged n East Asa, wth usng brcks n Chna, n Korea usng stone, and contnung to use wood n Japan. Korea has a plentful supply of hgh-qualty grante stone as the prmary materal, so they used grante to make unque and dstnct pagodas tradton stone n compare wth Chnese brck pagodas or Japanese wooden stone pagodas n comparson wth Chnese brck pagodas or Japanese wooden pagodas. By enterng Buddhsm nto Korea from Chna n the fourth century CE, the

3 frst pagodas were made of wood, lke Chnese pagodas. After the sxth century, Koreans mostly bult stone pagodas wth usng the grante from Korea s mountans. Nowadays Korea has more than 1,000 stone pagodas n dfferent styles, mostly n the form of three-story stone pagoda (Lee, 1998). a) Hgh-qualty grante b) Wood c) Dark gray brck Fg. 1 Materal classfcaton (Antque Alve, 2015) Number of stores classfcaton Three stores pagodas are more popular n Korea, among them, Seokgatap and Dabotap n Bulguksa Temple are the most renowned pagoda wth the saddest legends but there are some pagodas wth ten stores or more. Most of Korean pagodas has square archtectural plan, although some have round plan or have sx or eght sdes (polygonal). In East Asa each story of pagoda has ts own promnent skeleton rooflne, and the whole structure s capped by a pllar and plate. The form of pagoda manly s lke a monument (Chodzn and Kohn, 1998; Jo, 1995; Khan, 1985). a) Three-story b) Fve-story c) Seven-story Fg. 2 Classfcaton of Korean pagodas accordng to number of stores (Park, 2008)

4 3. PROPORTION ASSESSMENT OF KOREAN PAGODA STRUCTURES 3.1 Descrpton In ths study, to evaluate Korean pagoda structures proportons, three types of pagodas are chosen, ncludng three, fve and seven-story pagodas. Among the large number of pagodas, 30 samples of 3-story pagodas, 22 samples of 5-story pagodas, and 8 samples of 7-story pagodas are nvestgated, and are modeled n AutoCAD Partcularly, ther dmensons and proportons are studed. Most of these 60 pagodas are stone pagodas and only a few are made of brcks, whch are selected haphazardly. 3.2 Methodology To obtan and compare geometrcal proportons, a pagoda s dvded nto dfferent parts for a 3-story stone masonry structure, Seokgatap (Fg. 3(a)). The pagoda stands 8.2 m hgh, drectly across from Dabotap wthn the Bulguksa Temple complex n Gyeongju, Korea. It probably dates to around AD 751, when Bulguksa was completed. The pagoda conssts of four man parts: base sty lobate, body, roof, and head (Fg. 3(b)). In ths study due to the large varablty of the base stylobate and head of pagodas, studes have been focused on bodes and roofs. The body has key dmensons of heght, length, and wdth, and the roof has two key dmensons of length and wdth. Length Head Wdth Roof Length Roof Roof Wdth Body Heght Base Sty lobate (a) Fg. 3 Seokgatap [left] element defnton [rght] (Park, 2008) Varous dmenson ratos (proportons) are calculated from the frst floor up to the last floor. The rato equatons are shown below: (b) H h H 1 (1) where ρ h s heght rato, and H & H +1 are heght of body at th & +1 th floor, respectvely.

5 L l L 1 (2) where ρ l s length rato, and L & L +1 are length of body at th & +1 th floor, respectvely. W w W 1 (3) where ρ w s wdth rato, and W & W +1 are wdth of body at th & +1 th floor, respectvely. RL rl RL 1 (4) where ρ rl s roof length rato, and RL & RL +1 are roof length at th & +1 th floor, respectvely. RW rw RW 1 (5) Where ρ rw s roof wdth rato, and RW & RW +1 are roof wdth at th & +1 th floor, respectvely Three-story Intally, the mage data of 30 three-story pagodas were reproduced from pctures and three-dmensonally desgned n AutoCAD software. Then the szes and dmensons n specfed sectons were obtaned. Accordng to the above formulae, the dmenson rato was measured n dfferent parts. By comparng these ratos, the rato of 1.2 on average for all pagodas was obtaned. The results are shown n Table 1. The frst floor to second floor heght rato s much larger than the second floor to thrd floor heght rato because of the form and desgn of the three-story pagoda. However, regardless of the heght of the frst floor, the same rato of about 1.2 n all other components (.e., heght, length, wdth, roof length, and roof wdth) of the pagoda was acheved except for the H 1 /H 2. Table 1 Average values of proportons for 30 three-story pagodas Heght rato Length rato Wdth rato Roof length rato Roof wdth rato Proporton Average value for 30 three-story pagodas H 1/H H 2/H L 1/L L 2/L W 1/W W 2/W RL 1/RL RL 2/RL RW 1/RW RW 2/RW

6 3.2.2 Fve-story In the same way as was done for three-story pagodas, all fve-story pagodas were smulated by AutoCAD and the dmenson rato was measured n dfferent parts. In Table 2 t can be seen that the frst to second floor heght rato has the dfferent value than other floors ratos. Ths dfference s only n heght rato, so n other parts such as length, wdth, roof length and roof wdth all components have smlar ratos (about 1.5 ~ 2). Accordng to the study, there s almost no dfference between stone and brck pagodas n terms of proportons, and ths proporton s lkely to be used for aesthetc aspects, whch means materals dd not have substantal effects on the geometry of structures. The monuments appeared to be desgned and bult wth dfferent materals but n the same shape and proportons. Table 2 Average values of proportons for 22 fve-story pagodas Heght rato Length rato Wdth rato Roof length rato Roof wdth rato Proporton Average value for 22 fve-story pagodas H 1/H H 2/H H 3/H H 4/H L 1/L L 2/L L 3/L L 4/L W 1/W W 2/W W 3/W W 4/W RL 1/RL RL 2/RL RL 3/RL RL 4/RL RW 1/RW RW 2/RW RW 3/RW RW 4/RW Seven-story For dfferent sectons of the seven-story stone pagodas, all ratos were obtaned and shown n Table 3. As ndcated, the frst to second floor heght rato has also dfferent values n comparson wth other ratos. Based on the nvestgaton of taller pagodas, t can be seen that the heght of the frst floor s less than that n other types (heghts) of pagodas such as three-story or fve-story pagodas. The value of the heght rato of the frst to second floor has the lower value compared to the shorter pagodas. In Table 3, the comparatve ratos of heght, length, wdth, roof length and roof wdth of 8 sevenstory pagodas are shown and t can be seen that the average value for all seven-story pagodas s close to 1.10.

7 Table 3 Average values of proportons for 8 seven-story pagodas Proporton Heght rato Length rato Wdth rato Roof length rato Roof wdth rato Average value for 8 seven-story pagodas H 1/H H 2/H H 3/H H 4/H H 5/H H 6/H L 1/L L 2/L L 3/L L 4/L L 5/L L 6/L W 1/W W 2/W W 3/W W 4/W W 5/W W 6/W RL 1/RL RL 2/RL RL 3/RL RL 4/RL RL 5/RL RL 6/RL RW 1/RW RW 2/RW RW 3/RW RW 4/RW RW 5/RW RW 6/RW CONCLUSION Masonry stone pagoda structures bult n Korea are largely conssted of 3 parts: top part, body part and stylobate. The stylobate takes the role of foundaton, and the reducton of stylobate s bearng capacty may have a great nfluence on the safety of structures. In ths study, specfcally, the components of pagodas were classfed nto 4 man sectons such as stylobate, body, roof and upper part head. Through nvestgaton of a large number of pagodas n Korea, 60 pagodas (three-story, fve-story and sevenstory) were selected haphazardly from dfferent parts of Korea, among whch most of them were stone structures that are typcal types of pagoda structures n Korea. The nvestgaton of three-story, fve-story and seven-story pagodas was carred out usng AutoCAD to evaluate the geometrcal propertes of these ancent structures. Accordng to the nvestgaton of the thrty 3-story pagodas, many dmensonal proportons at each floor were found to be close to the value of 1.2, except for the frst to second floor heght rato. Ths means that the components of the floor are gettng smaller as the story ncreases but wth the same proporton. As can be seen n all types of pagodas, the frst floor heght above the base stylobate s larger than the heght of other floors. When gong forward from the three-story pagodas to the hgher pagodas, the

8 component s rato s gettng closer to the rato of 1.1, and also the proporton for the hgher floor s gettng smaller. Therefore, n general t can be concluded that except the frst to the second floor heght rato, the rest of the ratos s n between the values of 1.2 to 1.1 regardless the story number and heght. Ths research proves that a very regular and accurate pattern was appled n makng these stone and brck masonry structures that the archtects and engneers of that era amazngly have used. REFERENCES Antque Alve (2015), Korean Buddhst pagoda, from Chodzn, S. and Kohn, A. (1998), The wsdom of the crows and other Buddhst tales, Berkeley, CA: Trcycle. Jo, K., ed. (1995), Korean tradtonal art, Hexa communcatons, Korean culture and arts foundaton, Seoul, South Korea. Khan, N.I. (1985), Twenty Jataka Tales, Rochester, VT: Inner tradtons nternatonal. Lee, K.H. (1998), Sokkuram and Pulguksa, Samsung foundaton of culture, World hertage n Korea, Seoul, South Korea. Park, H.J., Km, D.S., and Choo,Y.W. (2014) Evaluaton of the sesmc response of stone pagodas usng centrfuge model tests, 12, Park, K.S. (2008), Korean stone pagoda, Hakyoun, Seoul, South Korea. Park, Y.S., Km, J.Y., Hong, S.I., Km, D.M., Jung, S.J., and Km, H.S. (2010), Structural behavour analyss of masonry stone pagoda consderng the nner constructon types of stylobate, Advanced Materals Research, , Son, C.-H., ed. (1994), Pagodas: Symbol of the Buddha, Korean cultural hertage, Korea foundaton, 1, Seoul, South Korea.