BRIDGES

SUSPENSION BRIDGE The suspension bridge is one of the oldest types of bridge. Early simple, or catenary, suspension bridges consisted of three or more cables made from vines, where people walked directly on the ropes to cross. A modern typical suspension bridge is a continuous girder with one or more towers erected above piers in the middle of the span. At both ends of the bridge large anchors or counter weights are placed to hold the ends of the cables. The main cables are stretched from one anchor over the top one of the tower(s) and attached to the opposite anchor. The cables pass over a special structure known as saddle. The saddle allows the cables to slide as loads pull from one side or the other and to smoothly transfer the load from the cable to the tower. From the main cables, smaller cables known as hanger cables or hanger ropes are hung down and attached to the girder. CABLE-STAYED BRIDGE A cable-stayed bridge is a bridge that consists of one or more columns (normally referred to as towers or pylons), with cable supporting the bridge deck. Cable-stayed bridges may look similar to suspensions bridges-both have roadways that hang from cables and both have towers. But the two bridges support the load of the roadway in very different ways. The different lies in how the cable are connected to the towers. In suspension bridge, cables ride freely across the towers, transmitting the load to the anchorage at either end. In cable-stayed bridge, the towers from the primary load bearing structure. A cantilever approach is often used for support of the bridge deck near the towers, but areas further from them are supported by cables running directly to the towers. This has the disadvantage, compared to the suspension bridge, that the cable pull to the sides as opposed to directly up, requiring the bridge deck to be stronger to resist the resulting horizontal compression loads; but has the advantage of not requiring firm anchorages to resist a horizontal pull as in the suspension bridge. All the static horizontal forces are balanced so that the supporting tower does not tent to tilt or slide. All static horizontal forces from the live loads. The steel-decked bridge designed at Stromsund by Franz Dischinger (1956) is therefore more often cited as the first modern cable-stayed bridge. The Tatara Bridge is a cable stayed bridge with total length of 1480 m and a center span of 890 m which is the longest center span in the world. But The Sutong Changjiang Highway Bridge over the Yangtze River is 1088 m main span and tallest cable towers when completed in 2008. CABLE-SUPPORTED ARCH BRIDGE The English word ‘arch’ stems from the Latin word ‘arcus’ meaning bow. Within this word lies the word ‘arc’, which refers to something round. We see arch-styled structures frequently in our neighborhoods. The triangle-shaped arches were made for the first time circa B.C 4000 in Mesopotmia. The structural advantages of transferring force by means of only compression enabled people to construct the arch made of stones in the Egyptian, Greek and Roman era. Around the nineteenth-century, the arch structure was made of steel and became the milestone in civil engineering history in the way that the long span bridge could be constructed with it. Nowadays steel and reinforced concrete are used as main materials, so they carry out the function of beam as well as the arch itself. Form the stone arch bridge as in Chongungyo, Baekungyo at Bulguk Temple in the united kingdom of Shilla and Geumchongyo (Changduk Palace). EXTRADOSED BRIDGE This type of bridge was first proposed by Jacques Mathivat in 1988. The tendons are arranged outside the girders, which are inside conventional girder bridge. It results in the prestressing force with greater eccentricity acting more effectively on the main girder. The external appearance resembles cable-stayed bridge, but the structural characteristics are comparable to those of girder bridges. The distinctive features of extradosed bridges are the followings. Applying the external prestressing, the girder hight can be set shorter than that of standard bridges. The cables (prestressing tendon outside the girders) need no tension adjustment necessary for cable-stayed bridges, and can be treated as usual tendons in the girder bridge. The height of pylons can be as half as those of cable-stayed bridges. Therefore easier construction can be executed. With small stress fluctuation under live load, the anchorage method for the stayed cables can be the same as that of tendon inside the girder, then the excess cost can be cut. It is the best choice that application of this type to a bridge with main span of 110-200m.

Sarjana Teknik Sipil

Teknik Sipil bukan hanya sekedar ilmu terapan, tetapi berhubungan dengan pemecahan masalah
nyata dalam kehidupan yang berdampak pada kualitas hidup masyarakat madani.
Sarjana teknik sipil bekerja pada lingkup luas termasuk pada sektor publik maupun swasta dalam menjawab tantangan saat ini seperti masalah pencemaran, pembangunan dan pemeliharaan sarana dan prasarana, banjir, gempa bumi, kemacetan lalu lintas dan pengembangan daerah perkotaan. Sarjana teknik sipil merencanakan, merancang dan membangun serta mengelola berbagai fasilitas dalam upaya memenuhi kebutuhan kehidupan yang manusiawi dan modern.
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