The presence of possible welding defects needs to be taken into account in order to get rational performance of welded structural member considering its fitness for purpose. Accordingly, it is necessary to identify fatigue performance of welded joint containing various defects. Fatigue performance of butt-welded joint specimens considering five types of defect, which are vary in size and location, is studied in wider fatigue life range. It is observed that the shape, size, and location of the defects considerably affect the fatigue performance of the specimens. Fatigue life prediction by fracture mechanics analysis based on current recommendation is generally conservative in long life region.
Kegiatan pengabdian masyarakat berbasis program studi ini dilaksanakan dengan melakukan pekerjaan pembangunan Jembatan Penyeberangan Orang (JPO) sepanjang 6 meter khususnya bagi masyarakat Kampung Pondok Manggis, Desa Bojong Baru RT. 03, RW 04, Kecamatan Bojong Gede, Kabupaten Bogor. Jembatan Penyeberangan Orang ini dilbangun untuk menghubungi jalan yang dipisahkan oleh sungai kecil yang mempunyai lebar sekitar 2 m. Sebelumnya jalan ini dihubungkan oleh jembatan dari beton yang ketinggiannya hanya 10 - 20 cm dari permukaan air sungai, sehingga kalau pada musim hujan jalan tersebut berada di bawah permukaaan air dan tidak bisa dilalui. Kegiatan ini dimulai dari persiapan, survey lokasi awal, dan pengajuan proposal bulan April 2018. Selanjutnya dilakukan tahap pelaksanaan peninjauan lapangan untuk menentukan teknis pelaksanaan yang sudah terlaksana pada tanggal 06-13 Oktober 2018. Dengan selesainya pekerjaan pembangunan jembatan penyeberangan orang tersebut maka akan tersedia prasarana jalan warga yang layak dan memperlancar kegiatan khususnya transportasi masyarakat desa terutama pada musim hujan. Metode yang digunakan untuk mencapai tujuan di atas adalah Kerjasama antara Tim pengabdian masyarakat Program Studi Perancangan Jalan dan Jembatan, Jurusan Teknik Sipil, Politeknik Negeri Jakarta dengan warga secara bergotong royong melakukan pembangunan jembatan tersebut.
Rust is a major problem in steel bridge construction because it has the potential to affect the integrity of the structure and is also an important consideration for inspection and maintenance programs. This study shows the results of laboratory tests on the effect of rust within 1 to 9 weeks on fracture toughness as one of the important mechanical properties of steel bridge elements. The specimens in this study were made of SM 490 type, steel commonly used for bridge construction. Rustless and rusted specimens were used with varying degrees of exposure after immersion in acid solution to simulate the rate of rust. The effect of rust rate on fracture toughness due to mass loss was studied. The fracture toughness of each specimen was monitored for those specimens with exposure periods of 1 week, 2 weeks, 3 weeks, 4 weeks, and 9 weeks to test their effect on toughness. The results of this study showed that there was no significant reduction in the rusting duration of 1 week, 2 weeks, 3 weeks, 4 weeks, and 9 weeks of fracture toughness. Rusting and testing activity for the long term is still ongoing and will be continued, as the results of this study greatly help bridge designers and asset managers to better model rust inspection and maintenance plans and assess the structural integrity of steel bridges affected by rust more accurately.
A lot of structures failure on the bridge, causes a collapsed to the bridges. The reason of the collapsed was dynamic loads that happen on the bridge. Dynamic loads make stress and relax happen at the same time. Fatigue analysis is an analysis that calculate the dynamic load that happen on the bridge, with counting the big vehicle or truck. Fatigue analysis can’t analyze all the element with one step. In this research the bridge was a truss bridge with span 70 m as the main structure. In fatigue analysis, stress that used was stress that caused by dead load and stress that caused by the big vehicle or truck passing through. The value between that stresses used to call stress range. In AASHTO the value of truck that passing truck in a traffic called Average Daily Truck Traffic (ADTT). Stringer, cross beam, and main truss was the element that will be analyzed. In this structure we use category B, where ADTT is 860, Threshold is 110 MPa, A is 39,3 x 1011, and the n is 1. From stress range that happen in the structure, we can find the age and ADTT until the bridge collapse because fatigue. In the end the elements that had the lowest age and the lowest ADTT was the main truss, where it just has 27 years old left and can only take 299 truck/day. Then the bridge has to get a maintenance and repair before it gets 27 years old.Keywords : Fatigue, age, ADTT, stress rangeAbstrakBanyak terjadinya kegagalan struktur pada jembatan, yang menyebabkan keruntuhan pada jembatan. Hal itu disebabkan oleh beban dinamis yang terjadi pada jembatan. Beban dinamis membuat terjadinya tegangan dan relaksasi dalam waktu bersamaan. Analisa fatik merupakan perhitungan dengan memperhitungkan beban dinamis yang terjadi pada jembatan, dengan beban dianggap sebagai kendaraan besar atau truk. Memperhitungkan kondisi fatik tidak dapat dihitung langsung untuk satu jembatan. Dalam analisa ini menggunakan jembatan dengan bentang 70 m sebagai struktur rangka atasnya. Pada Analisa fatik tegangan yang dihitung berupa tegangan akibat beban sendiri pada jembatan dan tegangan ketika dilalui oleh kendaraan besar atau truk. Perbedaan tegangan tersebut biasa disebut dengan stress range. Pada AASHTO, lalu lintas harian rata-rata (LHR) biasa disebut Average daily truck traffic (ADTT). Elemen yang dihitung berupa stringer, cross beam, dan batang rangka utama. Pada struktur ini kategori yang digunakan adalah kategori B dengan ADTT sebesar 860, threshold sebesar 110 MPa, A sebesar 39,3 x 1011 MPa3 dan n sebesar 1. Dari stress range yang didapat, maka dapat dicari umur jembatan serta ADTT hingga jembatan pada kondisi fatik. Dapat disimpulkan bahwa elemen yang mempunyai umur dan ADTT terendah adalah batang rangka utama, dengan nilai umur rencana 27 tahun dan ADTT 299 truk/hari. Dengan demikian dapat dinyatakan bahwa jembatan harus diberi perkuatan saat umur mendekati 27 tahun.Kata kunci : Fatik, umur rencana, ADTT, stress range.
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