Structural and non-structural elements can be combined into an aesthetic architectural structure and give some characteristics to the building. Wide spans buildings in Indonesia tend to have the effectiveness schemes which do not always give aesthetic or characteristic forms. Producing designs plans which have some characters can be done through the exposure and composition of structures in tectonics technology and materials approach as the main elements of the supporting structures. Maclaine Pont attempted to combine the hybridity of local (Indonesian) elements and Dutch material techniques in creating the wide spans building in the West Hall of Bandung Institute of Technology. The objective of this study is to know the pattern of wooden structures on the wide spans building which isthe West Hall of Bandung Institute of Technology which combines the effectiveness scheme on the structures and the representative structures on the cultural and natural factors. The method used was by breaking down the structural elements in the interior (interior element theory of D.K. Ching) with the understanding of archetypes. The results of the study show that the West Hall of Bandung Institure of Technology was formed from several patterns of wooden structures, namely the repetition dominance of arc structures and the trapezoidal trunks structure, as the main structure of the inner chamber, with a reinforcing block beam (skew) forming the letter Y and trapezium, as well as the bolt (bolt) as a binder between the main structure.
Keywords: Tectonics, acculturation, architecture, West hall, Bandung Institute of Technology
Structures are the parts in which buildings are made up, including foundations/footings, sloofs, walls, columns, rings, easels, and roofs. Structural elements have functions to support the existence of nonstructural elements including visible elements, interiors, and architectural details to form a single unit . Each part of the structure building also has its own function and role.
The development and advancement of technology in the modernism era of building materials technology have affected the buildings architecture in Indonesia, such as building materials using technology that can survive in the tropical climate, the process of building them which is easier, more precise and faster in its development. Many architects,developers, assigners are brought to the trend not because of the materials technology only but rather duplicate and receive completely external style and applied in the country. The effect is that the local architecture experiences an identity degradation.
Dutch colonial architect, Maclaine Pont, in this phenomenon, at that time had predicted the identity degradation problem. The Western Hall was used by Pont as an architectural experiment, local materials, new construction modeling techniques, woodworking technology, and in combining traditional country architecture with the advancement of modern construction techniques without forgetting the aesthetic and functional values. Innovative structural processing results expression potential of the overall architectural structure and artistic expression of the connection and construction details which are used.
The architectural elements in the physical sense are defined as the conditions in which the architecture operates. A room or a space can only be defined when it has a limit. When a space is formed by a boundary, there is a direct separation between the inner and outer space. The relationship between the two is determined by the quality of the boundary element. According to Francis D. K. Ching , the interior elements include floor, wall, ceiling, aesthetic, opening, and light elements. In this study, elements that feature wooden structures are wall, ceiling and opening elements and their understanding of aesthetic elements that refer to the design principles, namely the proportion, space scale, balance, space harmony, unity and space variation, room rhythm, . To give more understanding about structural patterns, archetype theory is used for that .
The theories stated in this research are used to classify the variation of architectural elements especially on the patterns of wood forming structure of West Hall of Bandung Institute of Technology and give descriptions on each variation in order to prove the existence of a common language of structure/form (common language of form). In reading the structure in more detail manner, the tectonics manner can be used according to Eko Agus Prawoto. The approach can make four tectonic- forming parameters the articulation of materials, the articulation of expression of load burden, the articulation of elements and articulation of manufacture process . Overall, it can be seen that the structure and architecture of the West Hall of Bandung Institute of Technology are classified into exposed structures, hidden structures, valued structures and unappreciated structures as proposed by Angus J. MacDonald . Exposed and valued structures include ornamentation of structures and structures as architectures. Exposed and unappreciated structures include structures as ornaments. A structure that is hidden and valued includes a structure as a form producer. Hidden and unappreciated structures include neglected structures.
The West Hall of Bandung Institute of Technology has a rectangular base shape in which in its each side, it has some additions (additive). The addition of buildings on the West side (Mass D), East building (Mass E) and North (Mass C) are smaller than the base shape (Mass A), while the South side of the building (Mass B) is longer than the base shape (Mass A). It shows that the hierarchy of Mass A is higher than the other buildings, Mass B and C have higher hierarchy than Mass D and E, while mass D is hierarchically equal to Mass E (Figure 1). The five building masses are tied to the surrounding corridor (Mass F) of the whole mass, or can be called as datum. When viewed entirely, the mass shape of the West Hall of Bandung Institute of Technology has a symmetrical shape on the central axis of the South North.
The hall has a high level of closure which has the outer and supporting areas in the West and East sides. However, it has a high openness with supporting rooms on the North and South sides. Therefore, it can be said that the main room from within is in Mass A, B and C. The structural pattern of wooden forming the interior of the West Hall of Bandung Institute of Technology on Mass A consists of the repetition of the square frame structure, while Mass B and C consist of the member plan structure which has isosceles trapezoidal frame structure that gives the impression of a linear space (Table 1). If it is compared to the local structures of wooden structures that have limited span of ± 6 meters, the use of stacked arched beam structures and clamps with iron rings can streamline wood dimensions and maximize until ± 15 m spans. The wood structure of Mass A, B and C is included in the structure exposed and appreciated which is as an architecture that is the form of an appreciation of the pure structure form on the interior of the West Hall of Bandung Institute of Technology.
Table 1: Pattern of Wooden Structure A, B and C Viewed from Cutting a section a – a
The construction pattern is made differently in the main room and the companion chamber with Room A with a linearly recurring Arched Beam pattern of five columns constructed with a half arch on the East and West sides, with the construction emphasized on the upper axis of the foam, Room B and C use the column and beam pattern (Straight Beam) with seven columns of repetition, but the area of C is greater than B in the area of Room A, the structure pattern of uses the plan structure with the help of skew on the roof supporting areas (Table 2).
Table 2: The Patterns of Skeleton System Wooden Structure
Mass A is structured from two and a half arcs which face each other and are connected at the upper midpoint, continued with a rigid structure that attaches to the skeletal structure of Mass B and C (Figure 2). The skeleton module is flanked by the isosceles trapezium-shaped skeleton united with flank system connections and cross-linking structures. The module is a module that undergoes linear repetition facing the West and East. The bonding of the structure between the repetitions of Western modules to the East is linked with the cross-sectional structures of varied degrees.
(Figure 3) forms a Y-shaped structure pattern when viewed from section b (Table 3). The difference of the skew pattern based on the load hierarchy is that the skew on the plane of the feet is wider than the top skew pattern and the uppermost pattern is smaller to support the roof, the skew which job is to support the beam so that the flexible wood can be nailed to support the load of the pull and press in the area above.
The interior of The West Hall of Bandung Institute of Technology shows the dominance of the wooden structures use representing the mass shape that Mass A has the highest hierarchy seen from the use of different structures from other rigid structural forms. Besides, from the height of the room, it can also be seen that Mass A has a vertical and horizontal wide expression with the use of the frame arc, it is in contrast with Mass B and C which only have a broad expression horizontally (Figure 4).
The repetition of modules to the West and East and the cross- section structures of varied degrees results in the expression of different Y structures and still show Mass A with the highest hierarchy. It can be seen that cross-secction structure of Mass B and C interior (Table 3, b-1 and b-2 pieces) have smaller open degrees compared to that of the cross section interior of A mass (Table 3, b-3 pieces). The cross section structures between the repitition of West and East structural modul on Mass A form repitition of structures in Y and triangle shapes because each corner of the cross section meet each other. Meanwhile, at Mass B and C, the corner of cross section do not meet each other. This shows that the structure of the Mass A of the cross section hold heavier loads than the cross section structure of Mass B and C. In other words, the hierarchy of the interior wooden structure of the West Hall of Bandung Institute of Technology of Mass A has the highest hierarchy, it is in line with the understanding of the visible mass structure reflected from the exterior.
Table 3: The Pattern of A, B and C Masses' Wooden Structure Seen From b Pieces
The repetition of cross-section structure has differences at the end of a room, or it can be said as the termination structure. On the longitudinal side, the structure termination has a corresponding direction to the previous repetition (Figure 5 and Figure 6), meanwhile on the short side of Mass B and C, they have the structures termination which are parallel to the direction of the previous structure (similar to Figure 9). On the other hand, the termination of the arc structure on the West and East sides uses a half arc structure which is placed perpendicular to the full arc structure (Figure 7 and Figure 9 on the right). The termination of the West and East side arc structure is connected with Mass D and E structures (supporting rooms on the West and East sides).
The wooden structure pattern forming Mass D and E is equal to Mass B and C’s, the difference can be seen at the distance of Mass D and E (Figure 7) which is shorter than B and C (Figure 5) and the difference in the structure termination pattern. Mass D and E have structures termination (Figure 7), which is parallel branches to the structure next to them, while Mass B and C (Figure 5) have structure terminations that have a contrary direction to the structure next to it. Therefore, when it is viewed as a whole, the walls of Mass D and E (Figure 7) have a triangular structure pattern, while Mass B and C (Figure 5) have trapezoidal patterns. For the upper sector of Mass B, C, D and E formers, it has similar patterns, which is isosceles trapezoidal rod frame structure.
Table 4: The Wooden Structure Patterns of Mass D and E as seen from Cutting c
Overall, the Mass D and E have similar structural forms to Mass B and C, but visually, they resemble more the cross- linking structures on Mass A that forms Y letter and a triangle (Figure 8). However, the height of the room and the room's structure can be said to be equal to Mass B and C, which indicates the overall supporting room that has a lower hierarchy than Mass A. The smaller room size than Mass B and C show that Mass D and E have the lowest degree in the whole building.
The structure development used by the interior of Bandung Institute of Technology's West Hall through the process of the connection system on the construction enhances the building expression by showing every existing detail on it. It is in line with the Frampton’s principle  about the tectonic cultivation as an important element in the construction of architectural forms. The pattern of wooden structure forming the West Hall of Bandung Institute of Technology shows that the element bears or supports and other elements that is in line with Mangunwijaya's thought , where there is an arc-shaped main structure flanked by a trapezoidal structure forming an interior room as well as supporting the roof structure above it, which is reinforced with a cross-section structure and a binding tool as a whole. Overall, the interior of Bandung Institute of Technology’s West hall is formed from the repetitive wooden structural elements. Therefore, it forms a linear space which is in line with the principle of display structure composition and a three-dimensional room according to Purnama Salura .
The interior's structural pattern of the West Hall of Bandung Institute of Technology is formed from the repetition of the arc frame structure in the main room (Mass A), the repetition of the isosceles trapezoidal frame structure in the supporting rooms that surround them (Mass B, C, D and E), with a cross- reinforcement block (sekur) forming the letter Y in the main room (Mass A), the cross-reinforcement block (sekur) forms a trapezoid on the long side of Mass B and C, the cross-block reinforcement (sekur) forms a triangle on the short side of Mass B and C and the entire boundary area (wall) of Mass D and E, and the clamping rod (pinchers) as a binder between the internal structure of each room or the bond between one mass structure and another. Overall, the pattern of interior structure forming the Bandung Institute of Technology 's West Hall has a symmetrical structure to the North and South axis and shows the highest hierarchy found in Mass A which has a wooden structure that is different from the supporting mass in its surroundings.