EASEC 11 Taipei November 30, 2008
Posted by dionsiringo in proceeding, visit.add a comment
This month I had a chance to attend the 11th East-Asia Pacific Conference on Structural Engineering (EASEC) in Taipei, Taiwan. It was a good conference, with many subjects and some of them are becoming very popular in civil engineering. The main topic of conference in structural engineering. This year special theme is about sustainability in civil engineering. The host of the conference is National University of Taiwan, which have done a tremendous work to put out such a good organization and arrangement.
with former advisor Prof. Iswandi Imran of ITB
This year conference is special because it was chaired by my prof, Prof. Fujino, so that many participants are from our research group. As always, conference is a good opportunity to learn what people have been doing and also to develop a network. I met a lot of old colleagues from previous EASEC conference (Bali 2003), and several alumni as well as my former lectures from ITB. I wrote two papers in this conference, one is a keynote as the second author co-written with Prof. Fujino and the other as the first author.
presenting a paper
Taipei itself is a nice city, a little similar with Jakarta but more humane. Transportation is not as good as it is in Tokyo, but they are cheap and readily available. Taxi fares in particular are very reasonable, while subway network is not as dense as it is in Tokyo, so we need to walk a lot to reach our destination when using subway.
Me with Taipei 101 on the background
The most obvious place in Taipei is Taipei 101 tower. It is the tallest existing building in the world, soon to be replaced by Burj Dubai. I had a chance to visit the building by taking the world’s fastest elevator. The building is equipped with TMD to prevent lateral vibration. In fact the elevator itself is equipped with control system.
IABSE Chicago and UIUC Trip October 1, 2008
Posted by dionsiringo in Structural Monitoring, Vibration, proceeding, visit.add a comment
Last week I attended the 17th IABSE Congress in Chicago. My colleague Dr. Nagayama presented a paper with me as the a co writer. The conference was great. Most of participants are engineers from big firms and famous consultants companies. Few are from academics. This sort of mixed audience is good for a change. It’s always a good thing to get feedbacks from engineers.
This is the paper presented at IABSE congress. It’s a modification of our previous works on bridge monitoring using ambient and seismic response. There are lots of paper that are very interesting to me, especially about long span bridge and tall building. I’ll post them next time.
Couple of days before IABSE Conference we visited the UIUC at Urbana-Champaign, where I visited Prof. Spencer’s Lab and participated on measurement of an old truss bridge using IMOTE2. The measurement was lead by Nagayama, couple of students from UIUC assisted us. It was a great experience. The collaboration was featured in UIUC research buletin.
Okutama Cable-Stayed Bridge : TMD for supression of Vortex-Induced Vibration April 3, 2008
Posted by dionsiringo in Bridge Engineering, Jembatan Cable-stayed, Teknik Sipil, Vibration, mechanical vibration, visit.4 comments
The Okutama Cable-stayed Bridge
Recently I had a very rare opportunity to go inside a cable-stayed bridge girder. The bridge is the Okutama Bridge, a single pylon cable-stayed bridge located at the Okutama area west part of Tokyo. The span length is 160 + 105 meter and the girder width is 12 m. The A-shape tower is made of steel reinforced concrete . The main girder is composed of double-span continuous steel double-box girder. Bridge construction was completed in 1996 and has become a part of the Okutama-Ohme Line in west part of Tokyo ever since.
We went inside the bridge following a group of Korean engineers, who are interested in the Tuned Mass Damper (TMD) system installed in this bridge. Unlike any other bridges that have TMD installed on the towers, in this bridge the TMD was installed on the girder.
The main reason for TMD installation is to suppress the Vortex-Induced Vibration (VIV) in vertical direction of the grider. As mentioned in the paper published by the designer and owner of the bridge, wind tunnel test of the current design girder revealed that vortex-induced vibration in vertical and torsional direction were evident under the wind velocity of 10 and 45 m/s, respectively. Both types of vibration had caused vertical amplitudes that were higher than the permissible one.
Tuned Mass Damper (0.8 ton of mass), main spring (white coil),and adjustable cantilever arm (in the middle)
In order to suppress the vibration, two measures were considered, one is aerodynamic measures by increasing aerodynamic damping using flaps, and the other is by mechanical measures such as installing a tuned-mass damper. The aerodynamic measure was abandoned for aesthetic and pedestrian safety precautions reasons, the TMD measure was selected instead.
Eight units of TMD were installed inside the girder, where each consists of mass (0.8 ton), springs (two of them: main and supporting springs) and a cylinder type of oil damper. The main spring, which has a form of coil, is connected to the mass by steel cantilever. Due to limited space inside the girder, the natural frequency of TMD is controlled by changing the position of the mass through an internal adjusting mechanism.
The bridge and its vibration control system are very impressive. In fact, it is the first girder VIV controlled bridge in Japan. However, when we visited the site, I was quite surprise to see that not so many passerby or vehicles crossing the bridge.
Tes Destruktif Skala-Penuh Jembatan Overpass March 19, 2008
Posted by dionsiringo in Bridge Engineering, Structural Monitoring, visit.add a comment
Minggu terakhir February saya habiskan di kota Vienna, mengunjungi kolega perusahaan konsultan engineering yang bergerak di bidang Structural Health Monitoring, namanya VCE. Ini adalah satu dari sedikit perusahaan yang menjadi SHM sebagai core-bussinessnya. Institusi lain biasanya bergerak di bidang riset atau proyek pemerintah.
Satu hal yang menarik dari kunjungan tersebut adalah bagaimana perusahaan tersebut dapat memadukan solusi engineering dan bisnis. Tak pelak, banyak pihak yang menganggap bahwa SHM masih berada pada tataran riset dan belum siap untuk terjun ke bisnis. Pihak VCE menjawab tantangan tersebut dengan cerdas. Satu hal yang mungkin kurang adalah keandalan solusi ilmiahnya. Untuk inilah mereka mengajak kerjasama dengan pihak universitas, salah satunya universitas tempat saya bernaung. Bentuk kerjasama seperti ini menjanjikan win-win solution. Mereka membutuhkan expertis sementara pihak universitas perlu belajar celah bisnis dan diversifikasi wilayah kerja.
Sebagai tahap awal dari kolaborasi riset kami dihadapkan dengan problem full-scale destructive test dapada sebuah highway bridge di Vienna. Jembatannya sederhana, post-tensioned overpass bridge, satu bentang 42 m. Sebelum dihancurkan, karena pelebaran jalan di bawahnya, serangkaian test dinamik dikerjakan pada jembatan tersebut. Kemudian, satu persatu kabel prategangnya dipotong. Pada waktu bersamaan getaran struktur direkam dan dimonitor. Dari hasil analisa getaran pada tiap tahap kerusakan, diharapkan kita dapat belajar mendeteksi moda-moda getaran yang disebabkan oleh kerusakan tersebut.
