Sharif University of TechnologyScientia Iranica1026-309824420170801On the assessment of a new steel bolted flush end-plate beam splice connection17351750426610.24200/sci.2017.4266ENH. KeikhaDepartment of Civil Engineering, Sharif University of Technology, Tehran, Iran.M. MofidDepartment of Civil Engineering, Sharif University of Technology, Tehran, Iran.Journal Article20150507This paper describes the development of a numerical model with the ability to simulate and analyze the mechanical behavior of dierent types of Double Bolted Flush End-plate Beam (DBFEB) splice connections, which thus far has not been reported. Moreover, Bolted Flush End-plate Beam (BFEB) splice connections have been investigated for calibration of the results using Finite Element Modeling (FEM). The initial stiness, rotation capacity, strength ratio, ductility, failure mode, and the performance of these two types of connections have been investigated and compared with each other with respect to FEMA 356. Also, classication of these two types of connections is performed by Eurocode 3 recommendation. The analyses have been calibrated and converted to experimental and analytical results, which are also briefly reviewed in this paper. Also, due to the multitudeof influencing parameters, an analytical description of the behavior of DBFEB connections has been delivered based on component method. Moreover, several parametric analyses on the Initial RotationalStiffness (Sini) of DBFEB connection have been conducted using regression analysis of FEM results.https://scientiairanica.sharif.edu/article_4266_2ca5883d337d883bc95c1205f0da4386.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Effects of viscoelastic supports on the behavior of bridges under moving vehicles17511769426710.24200/sci.2017.4267ENK. SamanipourDepartment of Civil Engineering, Sharif University of Technology, Tehran, IranH. VafaiDepartment of Civil Engineering, Sharif University of Technology, Tehran, IranJournal Article20150615One of the most important problems facing structural engineers is the analysis of dynamic behavior of bridges subjected to moving vehicles. In addition, viscoelastic supports under bridges change their dynamic behavior under passing trac loads. This paper presents how to model a bridge with viscoelastic supports and how the maximum dynamic stress of bridges changes during the passing of moving vehicles. Furthermore, this paper presents an algorithm to solve the governing equation of the bridge with viscoelastic supports as well as the equation of motion of a real European truck with dierent speeds, simultaneously. Using viscoelastic supports with appropriate characteristics can make a signicant dierence in the magnitude on the maximum dynamic stress of bridges. By nite dierence method, it will be shown that how much the stiness and damping of<br />viscoelastic supports should be to have less impact and dynamic stresses in the bridges. It will be demonstrated that using viscoelastic supports can decrease the local maximum DAFs in the case of short and medium spans up to 5%. This study becomes more important where vehicle speeds are considerably high; therefore, the consequences of a full-length analysis with viscoelastic supports must be used to design safe bridges.https://scientiairanica.sharif.edu/article_4267_a2a00ddfdffc2756609d831da1ba39cc.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Effects of edge rate of the designed line markings on the following time headway17701778426810.24200/sci.2017.4268ENN. DingSchool of Transportation, Wuhan University of Technology, 1178 Heping Avenue, Wuhan, Hubei 430063, ChinaS. ZhuSchool of Transportation, Wuhan University of Technology, 1178 Heping Avenue, Wuhan, Hubei 430063, ChinaH. WangSchool of Transportation, Wuhan University of Technology, 1178 Heping Avenue, Wuhan, Hubei 430063, ChinaN. JiaoPlanning Research Studio, Department of Transportation of Hubei Province, 428 Jianshe Avenue, Wuhan, Hubei 430030 China.Journal Article20150617Time headway is an important indicator for evaluating car-following safety.<br />To study the in<br />uence of edge rate on time headway in car-following, three patterns of<br />line marking were designed and placed on a real-world expressway, with actual vehicle<br /><br />ow data collected. Statistical analyses showed that (1) Time headways raised after the<br />installation of line markings compared with the original situation; and (2) When the value<br />of edge rate fell in [5 Hz,14 Hz], the time headway rose along the increase in the edge rate.<br />Furthermore, the increases in time headways were interpreted in relation with the leveling<br />up of the drivers' risk perception due to its overestimation in speed and underestimation<br />in distance caused by edge rate. The nding of this study suggests that the designed line<br />markings may benet engineers and decision makers in providing them with a new approach<br />to cope with critical issues in trac safety.https://scientiairanica.sharif.edu/article_4268_665f285f25980607379c9d660954167e.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Innovative theory for the compliance computation in rotors17791788426910.24200/sci.2017.4269ENA. RanjbaranDepartment of Civil and Environmental Engineering, Shiraz University, Shiraz, Iran.M. RanjbaranDepartment of Chemical and Petroleum Engineering, Sharif University of Technology, Tehran, IranJournal Article20150705The conventional energy release rate approach to the computation of the crack compliance in rotors is critically reviewed and its shortcoming is highlighted. The state functions and the generic compliance are introduced, dened, and veried. The proposed functions are dened based on the end states' conditions and are exact. The crack compliance of the shaft in torsion is explicitly dened as the function of the crack depth ratio and recommended as a good alternative to the classical procedure of the energy release rate method. The accuracy and eciency of the work are veried by concise mathematical formulation and comparison of the results of the work with the others in four examples.https://scientiairanica.sharif.edu/article_4269_14666d6337d0eb115341af94a1e68e22.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Estimation of scour downstream of a ski-jump bucket using the multivariate adaptive regression splines17891801427010.24200/sci.2017.4270ENA.H. HaghiabiDepartment of Water Engineering, Lorestan University, Khorramabad, IranJournal Article20150811In this paper, modeling the scour downstream of a flip bucket of spillways was considered using empirical formulas, soft computing techniques such as multilayer perceptron (MLP) neural network, and Multivariate Adaptive Regression Splines (MARS). For this purpose, 95 data sets were collected with regard to the most aective parameters on the scouring phenomena at downstream of spillways. During the MLP model development, it was found that the two transfer functions, such as log-sigmoid and radial basis, had very<br />suitable performances for predicting the desired scouring phenomena. The results of MARS model showed that this model with coecient of determination 0.99 and 0.91 during the development and testing stages, respectively, had suitable performance for modeling the scouring depth at downstream of flip bucket structure. The results of gamma test and MARS model indicated that q=(gd3 w), R=dw, and H=dw were the most aective parameters on the scouring phenomenahttps://scientiairanica.sharif.edu/article_4270_7c0cc32f667f91b1af4b89511c4fb040.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Detecting shoreline changes in Chabahar Bay by processing satellite images18021809427110.24200/sci.2017.4271ENS. ZeinaliDepartment of Civil and Environmental Engineering, Faculty of Engineering, Shiraz University, Shiraz, Iran.M. DehghaniDepartment of Civil and Environmental Engineering, Faculty of Engineering, Shiraz University, Shiraz, Iran.M.A. RastegarDepartment of Civil and Environmental Engineering, Faculty of Engineering, Shiraz University, Shiraz, Iran.M. MojarradDepartment of Civil and Architectural Engineering, the Royal Institute of Technology, KTH, SwedenJournal Article20150910Monitoring coastal areas is an important parameter in the sustainable development and protection of the environment. The expansion of constructions in Iran's southern coasts has not only led to the destruction of geomorphological landforms, but has also changed the process of erosion and sedimentation in coastal areas. Nowadays, remote sensing data are considered as the most ecient source of information for the study and<br />interpretation of coastal landforms, tidal levels, changes in coastline, depth of water, and so forth. The purpose of this study is to investigate the changes in the coastline of Chabahar Gulf, located on the coasts of the Oman Sea by using remote sensing techniques. This study examined and interpreted qualitative and quantitative changes of the coastlines in a forty-two-year period. Dierent supervised classication methods were used from which the most accurate one was ultimately chosen. The classied images were divided into two<br />classes of land and water, and the changes of these two classes between 1972 and 2014 were extracted. The net change results indicate that in the forty-two-year period, 1,832,436 m2 of the land has been added to water class, and 7,004,844 m2 of water has been added to land.https://scientiairanica.sharif.edu/article_4271_b7707c9647ca3fce0b7f50aa2749f143.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Multi-criteria optimization of concrete arch dams18101820427210.24200/sci.2017.4272ENM. PouraminianDepartment of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, IranM. GhaemianDepartment of Civil Engineering, Sharif University of Technology, Tehran, Iran.Journal Article20151020In this study, multi-criteria shape optimization of an asymmetrical doublecurvature arch dam is presented. Simultaneous cost minimization of dam construction and maximum allowable tensile stress are investigated for an economical and safe design approach in the current study. Pareto front method was used to balance both the economy and safety of the design simultaneously, which can be dicult for both analysts and<br />decision-makers. A non-dominated solution based on the important parameters of dam analysis and design is presented. To help decision-makers in their decision, two different methods are proposed. These methods for the case of an arch dam are Lombardi coecient and equilibrium point methods. The obtained results indicate that these two methods can be helpful for designers without experience and information of previous designs.https://scientiairanica.sharif.edu/article_4272_1bae77fcdae813e89fe8d6e6df661af7.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Seismic performance of reinforced concrete building in Guwahati city, northeast India18211833427310.24200/sci.2017.4273ENS. GhoshDepartment of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur 711103, IndiaS. ChakrabortyDepartment of Civil Engineering, Indian Institute of Engineering Science and Technology, Shibpur 711103, India.Journal Article20151102The seismic risk of reinforced concrete building frame located in the Guwahati City of northeast India is evaluated. To do so, we first conduct a site-specic probabilistic seismic hazard analysis to obtain hazard curve and implement proper selection of ground motion records for nonlinear time history analyses (NLTHA). Subsequently, the NLTHA of the building frame is performed to obtain the drift demand for any particular ground motion level. As the recorded accelerograms in the region are limited, the synthetic and artificial ground motion data are also generated to supplement the data base. Thereafter, the probabilistic structural capacity parameters at various limit states are obtained from random pushover analyses. Based on the knowledge of seismic hazard, demand, and capacity parameters, fragility curves are obtained corresponding to dierent structural performance levels. The annual probability of failure of the representative example frame<br />is also estimated. The results of the seismic risk analysis indicate that a medium-rise reinforced concrete building frame in the study area with moderate fundamental period is most likely to perform beyond its elastic range. However, such structures designed according to the Indian codes are expected to be sufficient enough to prevent life-threatening risk and complete collapse.https://scientiairanica.sharif.edu/article_4273_6ce650ae9e05c1073e61e60887ce04b0.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Dynamic load testing of a railway masonry arch bridge: A case study of Babak Bridge18341842427410.24200/sci.2017.4274ENSh. AtaeiSchool of Railway Engineering, Iran University of Science and Technology, Narmak, Tehran, IranA. MiriSchool of Railway Engineering, Iran University of Science and Technology, Narmak, Tehran, IranM. TajalliSchool of Railway Engineering, Iran University of Science and Technology, Narmak, Tehran, Iran.Journal Article20151108Health monitoring of masonry bridges is vital due to their long life in service and an increasing need for higher axle loads. Results of feasibility study of applying an increased axle load of 25 tons to an old masonry bridge are presented in this paper. Babak Bridge is located in north western zone of Iranian railway network and has been in service for more than 70 years. It consists of stone masonry blocks, has three long spans of 21.5 m,<br />7 spans of 10 m, and a total length of 270 m. Response of the bridge subjected to predened train loading by 15 sensors, including deflection meters, accelerometers, and strain gauges, is recorded. A total of 37 tests are carried out on Babak Bridge, and the results are used to calibrate the nite-element model of the bridge, which is developed by Abaqus software. The numerical model is then used to determine the weak spots of bridge due to subjection of higher axle loads for a possible strengthening procedure. Ultimate load-carrying capacity<br />of the bridge is also assessed by Ring software, which suggests a minimum adequacy factor of 1.25 for an axle load of 25 tons.https://scientiairanica.sharif.edu/article_4274_c00e3f0775a8b255fa2b4ca0056e8d0f.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Seismic performance evaluation of jacket-type offshore platforms using endurance time method considering soil-pile-superstructure interaction18431854427510.24200/sci.2017.4275ENH. HasaniDepartment of Civil and Environmental Engineering, Sharif University of Technology (SUT), Tehran, P.O. Box 11155-1639, IranA.A. GolafshaniDepartment of Civil and Environmental Engineering, Sharif University of Technology (SUT), Tehran, P.O. Box 11155-1639, IranH.E. EstekanchiDepartment of Civil and Environmental Engineering, Sharif University of Technology (SUT), Tehran, P.O. Box 11155-1639, Iran.Journal Article20151110In this paper, application of Endurance Time (ET) method in nonlinear seismic analysis of offshore pile supported systems has been studied. The ET method is a time-history analysis in which structures are subjected to intensifying articial acceleration functions. The ET method reduces complexity and computational demand of conventional nonlinear seismic analysis, and it provides response at dierent seismic levels in a single ET analysis. The aforementioned methodology has been applied to a typical model of single pile<br />and then to a functional jacket oshore platform in Persian Gulf region. Seismic response of aforesaid models by ET method has been compared with conventional time-history method. The results indicate that ET method is reliable in capturing seismic response of offshore platforms supported on piles with an acceptable accuracy.https://scientiairanica.sharif.edu/article_4275_f79d8b4fdd0cc8d159b91b1a3b968585.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Investigating the seismic behavior of RC shear walls with openings strengthened with FRP sheets using different schemes18551865427610.24200/sci.2017.4276ENB. Mohammadi VojdanDepartment of Civil Engineering, Razi University, Kermanshah, Iran.R. AghayariDepartment of Civil Engineering, Razi University, Kermanshah, Iran.Journal Article20160107This paper investigates the seismic behavior of RC shear walls strengthened by Fiber Reinforced Polymer (FRP) composites. In this research, the eects of strengthening shear walls with different strengthening schemes and also strengthening walls with openings in different dimensions and locations are studied. The development of nonlinear nite element methods has improved the accuracy of seismic analysis of complex structures. In this study, the ABAQUS software is used to investigate the nal resisting parameters,<br />ductility, and behavior factor in these walls using nonlinear static analysis. The ndings prove that the applied strengthening schemes increase the nal strength of the wall. Also, the increasing ductility, behavior factor, and increased overstrength factor in some of these walls compared with original walls are observed. The ndings also prove that special openings with limited dimensions to improve seismic behavior of the wall are eective, and the only limitation of using these openings is decreasing the nal strength which can be made up by using a proper strengthening scheme of FRP.https://scientiairanica.sharif.edu/article_4276_4a80bec62f112ae72a9af9a8a23bc31d.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Effects of moisture on warm mix asphalt containing Sasobit18661873427710.24200/sci.2017.4277ENH. NabizadehDepartment of Civil and Environmental Engineering, University of Nevada, Reno, NVB. NaderiDepartment of Civil and Environmental Engineering, Tarbiat Modares University, Tehran, Iran.N. TabatabaeeDepartment of Civil Engineering, Sharif University of Technology, Tehran, P.O. Box 11555-9313, IranJournal Article20150107The asphalt industry has been at the forefront of sustainable development. Warm Mix Asphalt (WMA) has been developed to cope with issues such as high energy prices and air pollution. These mixes require less energy and generate fewer pollutants during production in comparison with conventional Hot Mix Asphalt (HMA). Although a promising technology, the durability of WMA is not clear because long-term WMA field<br />performance data is limited. This study investigated the susceptibility of Sasobit-modied WMA to moisture, since moisture damage is a major cause of premature pavement failure in asphalt concrete. To this end, WMA samples were made using different concentrations of Sasobit and the results were compared with those from HMA mixtures. The effect of hydrated lime as an anti-stripping agent was also investigated. The tensile strength ratios indicate that the introduction of hydrated lime and Sasobit increased the resistance of<br />asphalt mixtures to moisture. Fracture energy and toughness were used to evaluate the crack resistance of specimens under dry and wet conditions. In comparison with Sasobit, hydrated lime increased crack resistance of mixtures. The results indicate that hydrated lime can be used as a compatible and effective anti-stripping agent for WMAs containing Sasobit.https://scientiairanica.sharif.edu/article_4277_feafc2652ebf4d7998044feb54322cce.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Study of pile behavior by improvement of confining soils using frustum confining vessel18741882427810.24200/sci.2017.4278ENA.H. KarimiDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, AUT, Tehran, IranA. EslamiDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, AUT, Tehran, IranM. ZarrabiDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, AUT, Tehran, IranJ. KhazaeiDepartment of Civil and Environmental Engineering, Amirkabir University of Technology, AUT, Tehran, Iran.Journal Article20150509A physical modeling apparatus made at Amirkabir University of Technology (FCV-AUT), called Frustum Conning Vessel, is employed to determine the effects of soil improvement on piles performance. The FCV-AUT is capable of linearly modeling the existing overburden stresses in the eld. Three types of Babolsar sand with relative densities between 20% and 70% were examined in these tests. Results of compression and tensile<br />load tests on seven piles, with the embedment length to diameter ratio (D/B) of 9, were used to evaluate the eects of soil improvement methods of soil densication as well as postgrouting on the piles performance. The results show that the increased bearing capacity by soil compaction from loose to medium state is greater than that of the medium to dense state. This increase has been observed to be a function of pile construction methods and pile tip conditions. Also, tip and/or side post-grouting enhanced the performance of bored<br />and concrete precast piles by increasing soil-pile interaction and its bearing capacity. The results of pile load tests carried out on the FCV-AUT have been observed to be well-aligned with the static bearing capacity calculations based on the API method.https://scientiairanica.sharif.edu/article_4278_72776039112b05f6934447d966e01866.pdfSharif University of TechnologyScientia Iranica1026-309824420170801Numerical modelling of the mechanical behaviour of steel brace modified by CFRP sheet18831888427910.24200/sci.2017.4279ENF. HatamiStructural and Earthquake Research Center, Amirkabir University of Technology, No. 424, Hafez Ave., Tehran, P.O. Box:
15875-4413, Iran.Z. BaheriStructural and Earthquake Research Center, Amirkabir University of Technology, No. 424, Hafez Ave., Tehran, P.O. Box:
15875-4413, Iran.Gh. OshaghStructural and Earthquake Research Center, Amirkabir University of Technology, No. 424, Hafez Ave., Tehran, P.O. Box:
15875-4413, Iran.Journal Article20150801One of the deciencies of diagonal (X) bracing is buckling under compressive load, hence not reaching the yielding threshold and being unstable. In this numerical study, the behavior of X-shape brace was investigated, which was modied by Carbon Fiber Reinforced Polymer (CFRP) plates that could absorb compressive force and make it stable. This innovative brace consisted of two separate steel plates connected by CFRP sheets to each other in the middle of the compressive element. Thus, these two parts were connected by epoxy resin and bolts. In this study, Finite Element Method (F.E.M.) was used to simulate the elements of steel and ber polymers by Abaqus software under cycle loading after designing of ber layers and connection type. Also, the numerical result was compared with the normal steel brace. The result showed that the innovative brace had more eciency under seismic response. According to this output, ductility and energy absorption increased in the innovative model (CFRP-BR), but stiness decreased as compared with the normal steel brace.https://scientiairanica.sharif.edu/article_4279_f4f9236fb9dc245c17a70cd2bd269dce.pdf