Tsunami telah menjadi isu panas sejak tsunami Lautan Hindi 2004 yang mengorbankan lebih daripada 200,000 orang daripada 14 buah negara termasuklah Malaysia, di mana seramai 68 orang telah meninggal dunia dalam kejadian tersebut. Walau bagaimanapun, kajian mengenai tsunami masih cetek terutamanya kajian tentang kesan struktur bersekitaran terhadap beban tsunami. Struktur bersekitaran dipercayai mampu menguatkan atau mengurangkan beban tsunami yang bertindak pada bangunan. Dalam kajian ini, kesan bangunan bersekitaran terhadap beban tsunami dan keberkesanan sudut kelegaan keracak dalam memudahkan kesan tersebut telah disiasat. Simulasi fizikal yang mensimulasi profil Barat Laut Pulau Pinang dan kesan unsur-unsur makro kekasaran pada 14° telah dilakukan terlebih dahula. Ini diikuti oleh sebanyak 299 set simulasi berangka dengan Flow-3D. Unsur-unsur makro kekasaran terletak pada sudut kelegaan keracak dari 5⁰ sehingga 50⁰ dan pada jarak antara unsur-unsur makro kekasaran dengan model bangunan sebanyak 5m, 10m, 15m, 20m dan 30m. Model bangunan setinggi 6.6m, 13.2m, 23.1m dan 26.4m telah digunakan dan dikenakan gelombang ombak setinggi 4m, 6m dan 8m. Sejarah masa beban tsunami setiap kes telah diplot dan beban tsunami maksimum pada dua puncak, iaitu puncak hentakan dan puncak gelombang pegun maksimum telah diekstrak. Faktor penguatan telah dikira dengan membandingkan beban tsunami pada kes yang menpunyai unsur-unsur makro kekasaran dengan garis asas yang tiada unsur-unsur makro kekasaran. Kesan ketinggian ombak, ketinggian bangunan dan jarak lega terhadap sudut kelegaan keracak dalam memudahkan interaksi telah dibincangkan. Empat hubungan untuk memudahkan kesan unsur-unsur makro kekasaran pada beban tsunami untuk keadaan yang berbeza telah dibangunkan dan ketepatan hubungan berkenaan untuk menjangkakan kuasa tsunami telah diuji.
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Tsunami has become a hot issue since the 2004 Indian Ocean tsunami that killed over 200,000 of people over 14 countries including Malaysia where 68 people were died in the tsunami attack. However, the study on tsunami is still shallow especially the study on the effect of surrounding structures to the tsunami loading acting on buildings. These structures are believed to amplify or reduce the tsunami loading acting on buildings. In this research, the effects of surrounding buildings on the tsunami loading and the effectiveness of wake clearance angle in simplifying the effect are investigated. Physical simulations that simulated the profile of Northwest of Penang Island and effect of macro-roughness elements at 14° were first conducted. It was followed by a total of 299 set of numerical simulations by using Flow-3D. Macro-roughness elements were located at wake clearance angle from 5⁰ to 50⁰ and at clear distance between them to building model at 5m, 10m, 15m, 20m and 30m in the numerical models. Building models of height 6.6m, 13.2m, 23.1m and 26.4m were used in this study and were subjected to wave height of 4m, 6m and 8m. The tsunami loading time history of each case was plotted and the maximum tsunami loading at the two peaks, namely impact peak and maximum standing wave peak were extracted. Force amplification factor was computed by comparing the tsunami loading at case with macro-roughness elements with the baseline condition which has no macro-roughness elements. The effects of wave height, building height and clear distance on the wake clearance angle to simplify the interaction were discussed. Four relationships that simplify the effect of macro-roughness elements on tsunami loading for different conditions were developed and their accuracy to predict the tsunami force was checked.
Effect of macro-roughness on tsunami forces / Chiew Lerk Qing