Perbaikan balok beton bertulang pasca kerusakan tahap first crack akibat beban siklik dengan metode jacketing kawat jala las segi empat

SUSANTO, Agus, Dr.-Ing. Ir. Andreas Triwiyono

2008 | Tesis | S2 Teknik Sipil

Wilayah Indonesia berada di antara empat sistem pelat tektonik yang aktif, sehingga termasuk daerah beresiko tinggi terhadap gempa. Gempa memberikan beban geser yang sering menimbulkan kerusakan pada bangunan. Kerusakan geser ini harus dihindari karena jenis kerusakan ini bersifat getas. Kebanyakan gedung yang sudah dirancang menurut peraturan bangunan tahan gempa mengalami kerusakan ringan akibat gempa. Penelitian ini bertujuan untuk mengetahui performa perbaikan struktur pasca kerusakan ringan (first crack) dengan metode jacketing kawatjala las segi empat, suatu metode yang murah dan mudah dikeijakan. Benda uji berbentuk pertemuan balok-kolom eksterior. Pembebanan dilakukan secara bolak-balik (siklik) sebagai simulasi beban gempa. Benda uji berjumlah 5 buah, yaitu : 1 buah benda uji standar geser (non-retrofit), 2 buah benda uji geser retrofit, 1 buah benda uji standar lentur (non-retrofit), dan 1 buah benda uji lentur retrofit. Kolom diberi beban aksial tetap sebesar 100 kN, sedangkan balok dibebani secara bolak-balik (siklik) sebagai simulasi beban gempa. Benda uji retrofit dibebani sampai mengalami first crack kemudian diretrofit dengan cara mengupas selimut beton. Selanjutnya balok dibalut dengan kawat jala las segi empat (1 lapis atau 2 lapis) kemudian diselimuti lagi dengan mortar khusus dan setelah kering diuji kembali sampai runtuh. Hasil penelitian menunjukkan bahwa kekuatan benda uji retrofit tidak hanya pulih seperti semula, bahkan meningkat secara signifikan. Kekuatan geser ultimit benda uji retrofit meningkat sebesar 40,19 % (1 lapis) dan 44,71 % (2 lapis), sedangkan kekuatan lentur meningkat sebesar 34,85 % (2 lapis). Daktilitas benda uji mengalami peningkatan sebesar 51 ,83 % - 116,58 %. Kekakuan benda uji, baik kekakuan awal, maupun tiap siklus pembebanan, mengalami penurunan. Seluruh benda uji mengalami pola retak yang sesuai dengan yang direncanakan. Kata kunci : kuat geser, beban siklik, retrofit

Indonesia lies between four active tectonrc plates which results in higher occurrence of earthquakes. Earthquake gives shear force which often causes damages to buildings. Shearfailure must be avoided because this kind of failure is brill/e. Normally, most building which are designed based on earthquake codes will only suffer light damage during earthquake. This research was subjected to know the performance of struclural retrofit method using "kawat Jala las segi empat" (galvanized welded wire mesh) on lightly damaged structure (first crack phase). The specimens were the model of exterior beam-column joint. Cyclic latera/load was applied to sunulate earthquake load. This research was using 5 specimens : I standard shear-fail specimen!, 2 retrofitted shear-fail specimens, I unretrofitted j lexure-fail specimen, and 1 standard flexure-fail specimen. A constant axial load of 100 kN was given to the column and then an increasing cyclic latera/load was applied to the beam. Standard specimens were loaded until collapse and not retrofitted as they were used as benchmark. Other specimens (retrofitted) were loaded until first crack occurred and then retrofitted by peeling the concrete cover. The cracked parts were wrapped with 1 or 2 layers of proposed wire (kawat jala las segi empat), and the concrete cover were reestablished afterward using specific cement mortar (Renderoc RG). Finally, after the re-established concrete cover dried, the retrofilled specimens were loaded again until collapse. The result shows that the strength of retrofitted specimens are not just fully recovered, but also increased significantly. The ultimate shear strength of retrofitted specimen increased by 40. 19 % (1 layer) and 44.71 % (2 layers), ultimatejle.xure strength of retrofitted specimen increased by 34.85% (2 layers). The ductility increased by 51.83 % - 116.58 %. The structural stiffness of retrofitted pecimens decreased. The crack pattern of all specimens occurred as planned. Keywords: shear strength, cyclic load, retrofit

Kata Kunci : Kuat geser,Beban siklik,Retrofit