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Xian Jiang - One of the best experts on this subject based on the ideXlab platform.
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a modified importance sampling method for structural reliability and its global reliability sensitivity analysis
Structural and Multidisciplinary Optimization, 2018Co-Authors: Zhen Zhou Lu, Xian JiangAbstract:The importance sampling method is an extensively used numerical simulation method in reliability analysis. In this paper, a modification to the importance sampling method (ISM) is proposed, and the modified ISM divides the sample set of input variables into different subsets based on the contributive weight of the importance sample defined in this paper and the maximum super-sphere denoted by β-sphere in the safe domain defined by the truncated ISM. By this proposed modification, only samples with large contributive weight and locating outside of the β-sphere need to call the limit state function. This amelioration remarkably reduces the number of limit state function evaluations required in the simulation procedure, and it doesn’t sacrifice the precision of the results by controlling the level of relative error. Based on this modified ISM and the space-partition idea in variance-based sensitivity analysis, the global reliability sensitivity indices can be estimated as byproducts, which is especially useful for reliability-based design optimization. This process of estimating the global reliability sensitivity indices only needs the sample points used in reliability analysis and is independent of the dimensionality of input variables. A Roof Truss structure and a composite cantilever beam structure are analyzed by the modified ISM. The results demonstrate the efficiency, accuracy, and robustness of the proposed method.
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an efficient reliability analysis method combining adaptive kriging and modified importance sampling for small failure probability
Structural and Multidisciplinary Optimization, 2018Co-Authors: Zhen Zhou Lu, Xian JiangAbstract:A vital challenge problem of structural reliability analysis is how to estimate the small failure probability with a minimum number of model evaluations. The Adaptive Kriging combined with Importance Sampling method (AK-IS) which is developed from the adaptive Kriging combined with Monte Carlo simulation (AK-MCS) is a viable method to deal with this challenge. The aim of this paper is to reduce the number of model evaluations of the existing AK-IS algorithm. Firstly, we use a contributive weight function to divide the candidate samples of model input variables generated in AK-IS. The candidate samples are used to select the best next sample to update the Kriging model in AK-IS. Secondly, select the best next sample only in the important area obtained according to the contributive weight value to failure probability to update the Kriging model until the stopping condition is satisfied. Thirdly, use the Kriging model constructed in the important area to predict the other area and update the important area by adding the point with the maximum contributive weight value in the area except the important area ceaselessly until the probability of the accurate identification on the limit state function’s signs (positive limit state value or negative limit state value) of all the importance sampling points satisfies a criterion. Finally, the updated Kriging model is used to estimate the failure probability especially for the small failure probability. The proposed method uses a thought from local to global in order to reduce the computational cost of AK-IS and simultaneously guarantees the accuracy of estimation. A non-linear oscillator system, a Roof Truss structure and a planar ten-bar structure are analyzed by the proposed method. The results demonstrate the efficiency and accuracy of the proposed method in structural reliability analysis especially for small failure probability.
Zhen Zhou Lu - One of the best experts on this subject based on the ideXlab platform.
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a modified importance sampling method for structural reliability and its global reliability sensitivity analysis
Structural and Multidisciplinary Optimization, 2018Co-Authors: Zhen Zhou Lu, Xian JiangAbstract:The importance sampling method is an extensively used numerical simulation method in reliability analysis. In this paper, a modification to the importance sampling method (ISM) is proposed, and the modified ISM divides the sample set of input variables into different subsets based on the contributive weight of the importance sample defined in this paper and the maximum super-sphere denoted by β-sphere in the safe domain defined by the truncated ISM. By this proposed modification, only samples with large contributive weight and locating outside of the β-sphere need to call the limit state function. This amelioration remarkably reduces the number of limit state function evaluations required in the simulation procedure, and it doesn’t sacrifice the precision of the results by controlling the level of relative error. Based on this modified ISM and the space-partition idea in variance-based sensitivity analysis, the global reliability sensitivity indices can be estimated as byproducts, which is especially useful for reliability-based design optimization. This process of estimating the global reliability sensitivity indices only needs the sample points used in reliability analysis and is independent of the dimensionality of input variables. A Roof Truss structure and a composite cantilever beam structure are analyzed by the modified ISM. The results demonstrate the efficiency, accuracy, and robustness of the proposed method.
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an efficient reliability analysis method combining adaptive kriging and modified importance sampling for small failure probability
Structural and Multidisciplinary Optimization, 2018Co-Authors: Zhen Zhou Lu, Xian JiangAbstract:A vital challenge problem of structural reliability analysis is how to estimate the small failure probability with a minimum number of model evaluations. The Adaptive Kriging combined with Importance Sampling method (AK-IS) which is developed from the adaptive Kriging combined with Monte Carlo simulation (AK-MCS) is a viable method to deal with this challenge. The aim of this paper is to reduce the number of model evaluations of the existing AK-IS algorithm. Firstly, we use a contributive weight function to divide the candidate samples of model input variables generated in AK-IS. The candidate samples are used to select the best next sample to update the Kriging model in AK-IS. Secondly, select the best next sample only in the important area obtained according to the contributive weight value to failure probability to update the Kriging model until the stopping condition is satisfied. Thirdly, use the Kriging model constructed in the important area to predict the other area and update the important area by adding the point with the maximum contributive weight value in the area except the important area ceaselessly until the probability of the accurate identification on the limit state function’s signs (positive limit state value or negative limit state value) of all the importance sampling points satisfies a criterion. Finally, the updated Kriging model is used to estimate the failure probability especially for the small failure probability. The proposed method uses a thought from local to global in order to reduce the computational cost of AK-IS and simultaneously guarantees the accuracy of estimation. A non-linear oscillator system, a Roof Truss structure and a planar ten-bar structure are analyzed by the proposed method. The results demonstrate the efficiency and accuracy of the proposed method in structural reliability analysis especially for small failure probability.
Muliawan Sutanto - One of the best experts on this subject based on the ideXlab platform.
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Analisa Pola Keruntuhan Konstruksi Rangka Atap dengan Menggunakan Profil Baja Ringan
Jurusan Teknik Sipil Fakultas Teknik Universitas Sriwijaya, 2013Co-Authors: Sucipta Andry, Saggaff Anis, Muliawan SutantoAbstract:Truss light steel is a modern technology of Roof Truss made of a thin plate of zinc-alum which is designed by computers and manufactured by machines. Truss light steel can be an alternative choice to support the Roof to be able to deal with the extreme weather conditions, not to be distracted from termite attack and to be held longer than Truss form wood. From its material, there are some weaknesses of light steel, among other are buckling and deflection occurs, so that a review was made of the failure that will occur in some spans and Truss forms. SolidWorks is a Computer Aided Design (CAD) 3D program using the Windows operating system. SolidWorks program can provide the simulation and compute the forces that arise in structures which designed by using finite element method. The use of SolidWorks program shows the simulation of failure mode that will occur, so it can be the input for the planning and construction of the better light steel. This analysis used the Truss of type pratt and howe with theoretical spans 12 m and 24 m at 300 angle. The components used were profile lip channel 75x32.8x7.95 and tek screw formed in SolidWorks program. The results obtained in the SolidWorks program was the failure occurred because of flexural buckling in A6 rod to the entire spans and forms. Truss pratt type was stronger to resist the loads on the theoretical span of 12 m and the howe type was stronger to resist the loads on the theoretical span 24 m. Diagonal mounting differences affected the strength of each spans. Key Words: Truss, light steel, SolidWorks, failure mod
Muliawan S. - One of the best experts on this subject based on the ideXlab platform.
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Analisa Pola Keruntuhan Konstruksi Rangka Atap dengan Menggunakan Profil Baja Ringan
'Faculty of Computer Science Sriwijaya University', 2013Co-Authors: Sucipta A., Saggaff A., Muliawan S.Abstract:Truss light steel is a modern technology of Roof Truss made of a thin plate of zinc-alum which is designed by computers and manufactured by machines. Truss light steel can be an alternative choice to support the Roof to be able to deal with the extreme weather conditions, not to be distracted from termite attack and to be held longer than Truss form wood. From its material, there are some weaknesses of light steel, among other are buckling and deflection occurs, so that a review was made of the failure that will occur in some spans and Truss forms. SolidWorks is a Computer Aided Design (CAD) 3D program using the Windows operating system. SolidWorks program can provide the simulation and compute the forces that arise in structures which designed by using finite element method. The use of SolidWorks program shows the simulation of failure mode that will occur, so it can be the input for the planning and construction of the better light steel. This analysis used the Truss of type pratt and howe with theoretical spans 12 m and 24 m at 300 angle. The components used were profile lip channel 75x32.8x7.95 and tek screw formed in SolidWorks program. The results obtained in the SolidWorks program was the failure occurred because of flexural buckling in A6 rod to the entire spans and forms. Truss pratt type was stronger to resist the loads on the theoretical span of 12 m and the howe type was stronger to resist the loads on the theoretical span 24 m. Diagonal mounting differences affected the strength of each spans
Desmaliana Erma - One of the best experts on this subject based on the ideXlab platform.
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Kajian Analisis Perbandingan Rangka Atap Kuda-Kuda Menggunakan Kayu LVL dan Baja Ringan
'Institut Teknologi Nasional Bandung', 2021Co-Authors: Diredja, Nessa Valiantine, Desmaliana Erma, Nuranita Badriana, Pertiwi, Anissa CahyaniAbstract:ABSTRAKPenggunaan baja ringan sebagai material rangka atap sudah sangat umum ditemui. Selain baja ringan, terdapat alternatif material lain yaitu kayu LVL atau Laminated Veneer Lumber. Pada penelitian ini dibahas mengenai penggunaan material baja ringan dan LVL sebagai rangka atap kuda-kuda pada hunian. Berdasarkan perhitungan, luas penampang antara kayu LVL terhadap baja ringan pada batang bawah memiliki perbandingan 7,31 dan 55,64, batang vertikal 6,10 dan 124,30, batang diagonal atas 33,67 dan untuk batang diagonal bawah 90,46 dan 5,33. Perbandingan tersebut menghasilkan yang lebih besar untuk kayu LVL. Meskipun didapatkan yang lebih kecil pada material baja ringan, namun terdapat persyaratan kelangsingan yang menyebabkan baja ringan memerlukan profil yang lebih besar. Sedangkan untuk lendutan didapatkan lendutan sebesar 0,88 mm rangka baja ringan dan 2,69 mm untuk kayu LVL, keduanya memenuhi persyaratan terhadap lendutan ijinnya. Untuk perbandingan berat, rangka baja ringan memiliki berat 24,99 kg dan kayu LVL sebesar 7,71 kg.Kata kunci: rangka atap kuda-kuda, baja ringan, kayu Laminated Veneer Lumber ABSTRACTThe use of cold-formed steel as a Roof Truss material is very common. In addition to cold-formed steel, there is other material alternatives that has a fairly light weight namely LVL or Laminated Veener Lumber. This study disscussed the used of cold-formed steel and LVL as a Roof Truss. The analysis result indicated that the section area between LVL to cold-form steel for bottom chord in the range of 7,31-55,64, and 6,10-124,30 for vertical beam, 33,67 for diagonal bottom chord, and 90,46-5,33 for diagonal top chord. As a result, of LVL was larger than cold-form steel. However, there are slendersness requirements that the cold-form steel was needed the larger profil than LVL. In terms of structure stiffness, the cold-form steel Roof Truss have 0,88 mm deflection and 2,69 mm for LVL, however they were able to accomodate the deflection requirements. The total weight of cold-formed steel is 24,99 kg and 7,71 kg for LVL.Keywords: Roof Truss, cold-formed steel, Laminated Veneer Lumbe
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Kajian Teknis Waktu dan Biaya pada Perbandingan Struktur Atap Kayu dan Struktur Atap Baja Ringan. (Hal. 118-129)
'Institut Teknologi Nasional Bandung', 2019Co-Authors: Aldiansyah Muhamad, Ratnayanti, Katarina Rini, Desmaliana ErmaAbstract:ABSTRAKRangka atap pada umumnya menggunakan material kayu sebagai struktur utamanya, tetapi kayu merupakan bahan yang didapatkan dari alam, jika digunakan terus menerus maka kayu akan habis. Maka dari itu produsen mencari altenatif lain yang dapat menggantikan kayu sebagai material utama membentuk struktur atap. Dibuatlah baja ringan sebagai pengganti material kayu yang semakin lama semakin langka dan juga mahal. Penelitian ini bertujuan untuk mengetahui perbandingan kekuatan, biaya, dan waktu antara struktur atap kayu dengan struktur atap baja ringan sehingga dapat dipilih struktur mana yang lebih baik dipilih. Hasil penelitian menunjukan kekuatan struktur kayu lebih baik dibandingkan dengan baja ringan, untuk berat struktur baja ringan lebih ringan sebesar 25,11%, untuk biaya baja ringan bisa menghemat 17,93% biaya, sedangkan untuk waktu pelaksanaan kayu dan baja ringan sama-sama 85 hari. penilaian total kayu mendapatkan 1,5 poin sedangkan baja ringan mendapatkan 2,5 poin, sehingga material yang baik dipilih adalah baja ringan.Kata Kunci: baja ringan, kayu, kekuatan, biaya, waktu ABSTRACTIn general, Roof Truss using wood as its main structure, but wood is obtained from nature, if used continuously then the wood will be runs out. Therefore manufacturers are looking for other alternatively cansubtitute wood as the main material to form the Roof structure. Cold formed steel was made to substitute wood material which is getting increasingly scarce and expensive as well. This research aims to find out a comparison of strength, cost, and time between the wooden Roof structure with cold formed steel Roof structure so that structure can be choosen which is the better one. Research results showed the strength of the wooden structure is better compared cold formed steel, for the weight of the structure cold formed steel lighter than wood, for the cost of cold formed steel 17,93% could save costs, for the timing of the implementation of wooden and cold formed steel is same need 85 days. Assestment of total wood get 1,5 points while cold formed steel get 2,5 points, so a better material chosen is cold formed steel.Keywords: cold formed steel, wood, strength, cost, tim
