K. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420221113The effect of earthquake frequency content and soil structure interaction on the seismic behavior of concrete gravity dam-foundation-reservoir system11016049810.52547/nmce.4.4.1ENH. MohammadnezhadAssistant Professor, Faculty of Civil, Water & Environmental Engineering, Shahid Beheshti University, Tehran, Iran.N. SaeednezhadMSc Student, Faculty of Civil, Water & Environmental Engineering, Shahid Beheshti University, Tehran, Iran.P. SotoudehPh.D. Candidate, Department of Civil Engineering, Sharif University of Technology, Tehran, Iran.Journal Article20221113The effect of frequency content on the dynamic response of concrete gravity dams is investigated in this paper. Dams are one of the most complex structures to handle when there is dynamic analysis involved. One of the influential parameters on these structures' seismic response is the frequency content of the earthquakes. An index to represent frequency content, which represents frequency content by PGA/PGV ratio(FCI) and sets three ranges including high(FCI>1.2), intermediate(0.8<FCI<1.2) and low-frequency content (FCI<0.8) is used in this paper. To simply study the effect of different frequency contents, a comparative analysis with different earthquake records with different frequency contents is performed on the finite element model of the Pine Flat concrete gravity dam. Results indicate a great influence of frequency content on the dynamic response of the structure. On a side note, to study the effect of soil-structure interaction, the same model has been analyzed under different modular ratios (modular ratio is the ratio of modulus of elasticity of the foundation of the structure Ef / Es. This is one of the simplest ways to introduce interaction effects in the analysis. The outcome states that different modular ratios (hence different soil-structure interaction participation) have an immense effect on the dam's dynamic response.https://nmce.kntu.ac.ir/article_160498_6add762e49f6c347090c5635b9f853e4.pdfK. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420200604Study on the Structural Behaviour of the Topside Modules of FPSO under the Forces Exerted on the Ship Hull112016049910.52547/nmce.4.4.11ENM. SalehPhD student, Faculty of Civil Engineering, University of Qom, Qom, Iran.R. AmirabadiAssistance professor, Faculty of Civil Engineering, University of Qom, Qom, Iran.A. KheiriMSc, Avantgarde Petro Energy Kish Company.Journal Article20200404The extraction of oil and gas from deep water is one of the most important challenges of the oil and gas industry today. FPSO is one of the leading platforms for deep waters. This study discussed the performance of FPSO deck modules under loads exerted on the hull of the ship. Modeling of the studied module was executed by SACS software and the effect of support using neoprene in the function of the module’s members was studied. The members of this module are divided into two general areas: the first area includes fulcrum members under the main deck of module and the second area includes installed members on the main deck and equipment of the module which is investigated in three directions; longitudinal, transverse and vertical. After analysis, it was confirmed that in the module which uses neoprene, the connected members to the neoprene have a significant decrease in relative stress, whereas, the transverse members exhibited increased relative stress. On the other hand, the vertical and longitudinal members displayed insignificant changes.https://nmce.kntu.ac.ir/article_160499_5d973a7bfd3f28516f59a07a358647b4.pdfK. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420200604Combining Structural and Non-Structural Measures for Optimal Management of Urban Surface Runoff Collection (Case Study: Ariafar Bridge in Mianroud Canal)212916050010.52547/nmce.4.4.21ENP. AbbasiPhD Student of Civil Engineering, Construction Management, Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran.B. AminnejadAssistant Professor, Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran.H. AhmadiAssistant Professor, Department of Civil Engineering, Roudehen Branch, Islamic Azad University, Roudehen, Iran.Journal Article20200404Today, various structural and non-structural solutions are used to control and reduce the negative effects of floods in investigation and executive projects. But what is certain is that the optimal solution to minimize flood damage is a combination of structural and non-structural methods (planning and response measures). It is essential to provide these solutions in a metropolis like Tehran because the hydrographic network of Tehran runoff is sometimes incomplete during floods and is accompanied by severe flooding. Therefore, in this study, a combination of the mentioned methods were used for a part of Tehran's Mianroud canal (as one of the most important surface water management facilities in the catchment area of west Tehran) called Ariafar Boulevard Bridge. For this purpose, in the first step, severe accident hotspots along the route were investigated and then the capacity of passing on accident-prone routes was evaluated according to hydrological information under different scenarios (discharges with return periods of 5, 10, 25 and 100 -years). The results show the adequacy of channel capacity for a 10-year return period. But for the 25, 50 and 100-year discharge, we will face 8.88%, 28.93% and 50.81% capacity shortages, respectively. In the second step, considering the structural solutions, the methods of eliminating the capacity shortage of bottlenecks, including correcting the route, installing auxiliary routes, or destroying bridges that prevented the transfer of runoff in the canal route were carefully examined. The results showed that the combined use of structural and non-structural methods increases the effectiveness and significantly reduces the risk of flood spreading in the city.https://nmce.kntu.ac.ir/article_160500_5e2547d02ae7ce43ca31f90ded84995e.pdfK. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420200527Influence of Dilation Angle of Soil on Seismic Displacements of Gravity Retaining Walls using Upper Bound Limit Analysis Method303616050110.52547/nmce.4.4.30ENP. SharifiGraduated Student, Department of Civil Engineering, University of Tehran, Tehran, Iran.O. FarzanehAssociate Professor, Department of Civil Engineering, Faculty, University of Tehran, Tehran, Iran.F. AskariAssociate Professor, Geotechnical Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran.Journal Article20200401In this paper, permanent displacements of gravity retaining walls with back and front fill under seismic excitation due to sliding is investigated. In this regard, by using the upper bound theorem of limit analysis, an expression is presented for obtaining the yield acceleration coefficient and also, critical angles of failure wedges are calculated. Several comparisons are made with other solutions in literature. Effect of variation of dilation angle and ratio of the height of front fill to backfill soil is evaluated on seismic performance of a gravity retaining wall. Results showed that by increasing dilation angles from zero to internal friction angle of the soil, the values of seismic displacement inclines.https://nmce.kntu.ac.ir/article_160501_bc36eb682320e327be9893eb1e85bd60.pdfK. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420200627Static and Dynamic Safety Evaluation of A Heightened Arch Dam Including Massed Foundation Effects374816050210.52547/nmce.4.4.37ENH. MirzabozorgAssociate Professor, Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran.M. GhaemianAssociate Professor, Department of Civil Engineering, Sharif University of Technology, Tehran, IranS. M. AghajanzadehPh.D., Department of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran.Journal Article20200401DEZ dam is a double curvature arch dam built between 1959 and 1963. After more than 50 years of operation, the reservoir's storage capacity was reduced due to sedimentation, threatening its useful life and power intake. Several solutions were examined, and heightening the dam body was chosen as the most economical solution. Consequently, the seismic safety of the heightened structure was seen as indispensable. This study investigates the seismic safety of DEZ dam, considering the effects of heightening the dam body. Static loads and two levels of OBE and MCE earthquakes are applied to the finite element model of the dam-massed foundation-reservoir system. In static loadings, local stress concentration occurs in the heightened dam. Additionally, under the OBE earthquake, some limited damage is predicted, which is not problematic for dam safety. Finally, Under MCE records, some cracked regions are developed. Still, the model does not show general instability, and so, the cracked areas do not lead to the release of the reservoir.https://nmce.kntu.ac.ir/article_160502_53330c8dcb29c2e49f8fafd579774205.pdfK. N. Toosi University of TechnologyNumerical Methods in Civil Engineering2345-42964420200620Numerical Methods of Visco-elastic Segments on Water Hammer Pressures495716050310.52547/nmce.4.4.49ENJ. Rahimi FiruzM.Sc., Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran.S. R. Sabagh YazdiProfessor, Faculty of Civil Engineering, K. N. Toosi University of Technology, Tehran, Iran.A. KeramatAssistant Professor, Faculty of Civil Engineering, Jundishapur University of Technology, Dezful, Iran.Journal Article20200420Water hammer is a phenomenon accompanied by damage, vibration and noise. In order to deal with this phenomenon, different solutions have been proposed. Mechanical behavior of pipe material can significantly affect pressure responses of the pipe system during the transient flow. Utilizing viscoelastic pipe segments for attenuating the water hammer pressure may be considered as a damping mechanism alternate. The aim of this study is investigating the use of viscoelastic materials such as polyethylene in absorption of water hammer energy. The governing equations in this phenomenon are comprised of Continuity Equation and Momentum Equation. Discretization of the equations is done/performed by employing the Method of Characteristics (MOC). Verification of the developed numerical method is done/executed by comparing the results with the empirical results obtained from another study preformed earlier. The comparison between the results demonstrates that the numerically obtained results have acceptable accuracy. Also the effect of variations in the values of different parameters on decreasing the induced pressure is investigated. Numerous studies have been conducted on visco-elatic pipes; the innovation in this study however, is combining the use of visco-elastic and elastic material in the same pipe for cushioning the effects of water hammer.https://nmce.kntu.ac.ir/article_160503_d2a376337c72309ff9b46a986cb582ec.pdf