2020-12-02T11:05:30Z
http://scientiairanica.sharif.edu/?_action=export&rf=summon&issue=344
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Long-term flexural behavior of reinforced baked clay beams
N.A.
Lakho
M.
Auchar Zardari
Clay is a low cost and environment-friendly material for construction. On firing, it gets hard and attains compressive strength as high as normal concrete. This paper presents the flexural behaviour of singly reinforced baked clay beams under longterm sustained loads. The loads applied at midspan of these beams were 30%, 40%, and 50% of their short-term failure load for a period of 360 days. The results show that therate of defection, formation of cracks, and their stabilization was completed in a certain period of time depending on the intensity of the long-term sustained loads. In the first and second loading conditions, this period of opening and stabilization of cracks was 100 and 77 days, respectively. Then, the defection increased with a decreasing rate. While in the case of 50% of loading condition, the period of formation and stabilization of cracks was reduced to only 50 days, and then these cracks became dormant and no new crack was developed with respect to time. After that, negligible midspan defection was observed with time. In addition to this, the defection in these beams was more compared to the estimated long-term defection according to ACI code.
Baked clay beams
Sustained loads
Ultimate loading capacity
Defection
Cracks
2017
06
01
877
883
http://scientiairanica.sharif.edu/article_4072_6606520a83469ebbfff03d67f95e7276.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Effect of record scaling on the behavior of reinforced concrete core-wall buildings subjected to near-fault and far-fault earthquakes
H.
Beiraghi
A.
Kheyroddin
M.A.
Kafi
In this paper, two distinct record scaling methods, Spectrum-Matching (SM) and Amplitude Scaling (AS), were used to study the seismic behavior of reinforced concrete core-wall buildings subjected to Near-Fault (NF) and Far-Fault (FF) strong ground motions. First, the core-walls were designed based on seismic codes. Next, nonlinear fiber element models of the core-walls were prepared using the extended plastic hinge and the single-plastic hinge approaches. The SM and AS methods were used to obtain appropriate records for use in nonlinear time history analysis. Amplitude scaling procedure led to larger curvature ductility demand at the upper levels of the buildings, and this issue was more critical for the near-fault ground motions. On the other hand, SM procedure led to larger curvature ductility demand at the lower levels and less curvature ductility demand at the upper levels. The reason for this difference was the changes in the ground motion characteristics due to SM procedure. The changes in the ground motion characteristic were more severe for near-fault ground motions. For NF records, mean period of the SM records was 0.67 times that of the AS records, and shows that the frequency content of the SM-NF events was affected by SM process.
Reinforced concrete
core-wall
near-fault
Far-fault
Record scaling
2017
06
01
884
899
http://scientiairanica.sharif.edu/article_4073_0b45dd3a112a23d807162c9e8a8ab05f.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
State of the art on the maximum strength of masonry infilled frames
M.
Mohammadi
For infill panels, the expected strength is very close to the cracking strength; however, experimental values of the cracking strength are very scattered, and there is no formula to estimate it accurately. That is why some new codes have been assumed to focus on determining the expected strengths of Infill panels by their maximum strengths. In this paper, an extensive statistical analysis is conducted on experimental data toachieve a formula for the maximum (mostly referred as ultimate) strength of solid masonry infilled frames. For the ultimate strength, reliability of the existing empirical relations (9 formulas) is investigated, based on the available experimental data, categorized in accordance with their conning frames. The obtained results of 51 experimental specimens show that the formula, recommended by Maintone et al., is the best one; however, it mostly underestimates the ultimate strength and is more accurate for the inlls in concreteframes. The formula is also improved to have a better correlation with the experimental data.
Strength
Masonry
Infill panel
Seismic design
Ultimate strength
Equivalent strut
2017
06
01
900
909
http://scientiairanica.sharif.edu/article_4074_a6114767bedc086dc02f63f65c5412c3.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Selection and scaling of spectrum-compatible ground motion records using hybrid coded genetic algorithms
S.
Yaghmaei-Sabegh
S.
Karami
M.
Hosseini-Moghadam
This paper presents a new searching framework for optimal scaling of earthquake ground motion records as inputs for dynamics analysis. Two hybrid-coded Genetic Algorithms (GA), named real-permutation and binary-permutation GA, are effectively used to solve an applicable optimization problem in earthquake engineering field. Methodologies are outlined to choose a set of ground motions, with a good level of t to the design spectrum, and the corresponding scales simultaneously during a hybrid-coded process. The effects of dierent parameters used in design of algorithms are investigated through sensitivity analysis to suggest a set of proper input values. Analysis showed that the sensitivity of the binary-permutation GA results to input parameters variations is less than that of real-permutation GA. The paper also concludes that binary-permutation GA is slightly more reliable than real-permutation GA; accordingly, it is recommended as asuitable algorithm to select and scale spectrum-compatible ground motion records.
Ground motion scaling
Time history analysis
Design spectrum
Genetic Algorithm
Hybrid-coded genetic algorithm
2017
06
01
910
925
http://scientiairanica.sharif.edu/article_4075_2326a94a34d95ae1460d8be83235f5db.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Wind turbines design corrections for next Galicia climatic conditions
J.A.
Orosa
A. M.
Costa
G.
Roshan
E.J.
Garcia-Bustelo
Galicia, placed in northwest of Spain, is a clear example of global wind energy development as a consequence of its climate conditions. Despite this fact, previous research works have indicated a climate change in the next years that must be considered at the time of wind turbine design, selection, and placement. In this work, information about weather conditions and power output from twenty four wind turbines was sampled in a typical year, and a statistic study was done. Based on this information, a model that relates weather to power conversion in this particular region and wind turbines model was obtained. This particular procedure lets us define the effect of climate change over wind power on Galician wind farms. Results showed a 10% power output fall during spring and summer seasons. Therefore, future studies about new technologies that work out well under those conditions, such as low wind turbines, must be done. At the same time, results can be employed for future wind turbines placement optimization. Finally, nowadays, there is no standard or procedure to consider this highly complex situation, and so the present work aims to be the initial guide.
Wind energy
Climate change
Moist air
Power
Wind farm
2017
06
01
926
932
http://scientiairanica.sharif.edu/article_4076_d3b5afd16bf705ab59ecdf302f7c02c4.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Probabilistic seismic hazard analysis using reliability methods
M.
Kia
M.
Banazadeh
By considering uncertainties in the input parameters (e.g., magnitude, location, wave path, etc.), the Probabilistic Seismic Hazard Analysis (PSHA) aims to compute annual rate of various exceeding ground motions at a site or a map of sites of all anticipated given earthquakes. Uncertainties may be originated due to inherent randomness of the phenomena or variability in the mean values of dierent models parameters, mainly due to use of nite-sample size of observations. The rst, in literature reviews, is commonly named aleatory uncertainty; the second is known as epistemic uncertainty. The total probability numerical integration, generally employed to calculate PSHA, only considers aleatory uncertainties, and variability in the models' parameters is neglected to simplify calculation. In this paper, as an alternative to the total probability numerical integration, matured and standard reliability methods tailored to eortlessly consider both types ofuncertainties are put forward to compute site-specic PSHA. Then, as an application study, the peak ground acceleration hazard curve for the site, at which a historical bridge is located, is developed and compared with those obtained from the total probability numerical integration.
Probabilistic seismic hazard analysis
Reliability methods
Probabilistic model
Epistemic and aleatory uncertainties
Limit-state function
2017
06
01
933
941
http://scientiairanica.sharif.edu/article_4077_2f53979d36024454e031cafbdf49080a.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Strength and elastic moduli of a concrete bridge using advanced nondestructive techniques
M.A.
Hadianfard
H.
Marzouk
C.
Shafieyanb
In this research, Non-Destructive Test (NDT) wave tomography techniques are used to estimate the strength and elastic moduli and to assess the health condition of the piers of an existing concrete bridge. There are various empirical relationships to evaluate concrete characteristics based on NDT techniques. However, it is not clear which empirical relationship matches the desired concrete better. Therefore, using only one empirical model can lead to inaccurate results. In the current investigation, the mean value of several appropriate relationships is considered as the desired value. Also, the use of only one NDT technique causes some errors. In order to accurately estimate the concrete characteristics, the combination of two or more nondestructive methods is very efficient. In this research, data of Ultrasonic Pulse Velocity (UPV) and shear wave velocitytests are used simultaneously. The results show that the combination of the two criteria of strength and elasticity and using an average value of several empirical models give a relatively accurate scale for assessment of the concrete condition. The results show the ability and eciency of the combination of two different NDT methods to estimate the strength, elastic moduli, and health condition of the concrete structure.
Ultrasonic Pulse Velocity
Shear wave velocity
compressive strength
dynamic modulus of elasticity
Nondestructive test
Mira-3D
2017
06
01
942
952
http://scientiairanica.sharif.edu/article_4078_49c8c93de1371f2122a6d968c5b19a35.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Arc based ant colony optimization algorithm for solving sewer network design optimization problem
R.
Moeini
In this paper, Arc Based Ant Colony Optimization Algorithm (ABACOA) is used to solve sewer network design optimization problem with proposing two different formulations. In both of the proposed formulations, i.e. UABAC and CABAC, the cover depths of sewer network nodes are taken as decision variables of the problem. The constrained version of ABACOA (CABAC) is also proposed in the second formulation to optimally determine the cover depths of the sewer network nodes. The constrained version of ABACOA is proposed here to satisfy slope constraint explicitly leading to reduction of search space of the problem, which is compared with that by the unconstrained arc based ACOA (UABAC). The ABACOA has two signicant advantages of efficient implementation of the exploration and exploitation features along with an easy and straightforward denition of the heuristic information for the ants over the alternative usual point based formulation. Two benchmark test examples are solved here using the proposed formulations, and the results are presented and compared with those obtained by alternative point-based formulation and other existing methods. The results show the superiority of the proposed ABACOA formulation, especially the constrained version of it,to optimally solve the sewer network design optimization.
Arc based ant colony optimization algorithm
Sewer network
Exploration
Exploitation
Heuristic information
Optimal design
2017
06
01
953
965
http://scientiairanica.sharif.edu/article_4079_d486bc42109518f864fcbd1e02135b5f.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Three-dimensional axisymmetric responses of exponentially graded transversely isotropic tri-materials under interfacial loading
Y.
Zafari
M.
Shahmohamadi
A.
Khojasteh
M.
Rahimian
In this paper, an analytical formulation is presented to study an exponentially graded transversely isotropic tri-material under applied axisymmetric point-load and patchload with the aid of Hankel transform and use of a potential function. The given formulation is shown to be reducible to the special cases of (1) an inhomogeneous nite layer on a rigid base; (2) exponentially graded bi-material or half-space under applied buried loads; (3) homogeneous tri-material or bi-material solid. Several numerical solutions are presentedto explain inhomogeneity eect on the stress transfer process in the inhomogeneous threelayered medium by means of a fast and accurate numerical method.
Functionally graded material
Exponentially graded
Transversely isotropic
Displacement potential
Tri-material
Axisymmetric green's function
2017
06
01
966
978
http://scientiairanica.sharif.edu/article_4080_26175b101812b4f22012ffeaa811784d.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Influence of foundation flexibility on the seismic response of low-to-mid-rise moment-resisting frame buildings
H.
Tahghighi
M.
Rabiee
Recent studies have shown that the effects of Soil-Structure Interaction (SSI) may be detrimental to the seismic response of structure, and the neglect of SSI in analysis may lead to an un-conservative design. The objective of this study is to simulate the performance of multi-storey building-foundation systems through a Winklerbased approach. Four typical steel Moment-Resisting Frame (MRF) buildings on three soil types with shear wave velocities of less than 600 m/s subjected to actual ground motion records of varied hazard levels are modeled with and without SSI. It is observed that the performance level of models supported by flexible foundation, particularly in an intense earthquake event, may alter signicantly in comparison to fixed-based structures. Moreover, for MRFs on soft soil, the nonlinear foundation is found to have a signicanteffect on the force and displacement demands. This indicates the necessity for consideration of flexible foundation behavior in the modern design codes in order to accomplish a more economic yet safe structural design.
seismic response
Soil-structure interaction
Moment-resisting frame
Nonlinear Analysis
Design code
2017
06
01
979
992
http://scientiairanica.sharif.edu/article_4081_584b5cb4fa10a69e40eb0bc2734e50a5.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Application of trend analysis and artificial neural networks methods: The case of Sakarya River
G.
Ceribasi
E.
Dogan
U.
Akkaya
U.E.
Kocamaz
Various articial intelligence techniques are used in order to make prospective estimations with available data. The most common and applied method among these artificial intelligence techniques is Artificial Neural Networks (ANN). On the other hand,another method which is used in order to make prospective estimations with available data is Trend Analysis. When the relation of these two methods is analyzed, Artificial Neural Networks method can present the prospective estimation numerically, while there is no such a case in Trend Analysis. Trend Analysis method presents result of prospective estimation as a decrease or increase in data. Therefore, it is quite important to make a comparison between these methods which brings about prospective estimation with the available data, because these two methods are used in most of these studies. In this study, annual average stream flow and suspended load measured in Sakarya River along with average annual rainfall trend were analyzed with trend analysis method. Daily, weekly, and monthly average stream flows and suspended loads measured in Sakarya River and average daily, weekly, and monthly rainfall data of Sakarya were all analyzed by ANN Model. Results of trend analysis method and ANN model were compared.
Trend analysis
Artificial Neural Networks
Sakarya river
Rainfall
Stream flow
Suspended load
2017
06
01
993
999
http://scientiairanica.sharif.edu/article_4082_7efaafcf4da6866f1b089304b1c78a32.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Development of group method of data handling based on genetic algorithm to predict incipient motion in rigid rectangular storm water channel
I.
Ebtehaj
H.
Bonakdari
F.
Khoshbin
Ch. Hin Joo
Bong
A.
Ab Ghani
Sediment transport is a revalent vital process in fluvial and coastal environments, and \incipient motion" is an issue inseparably bound to this topic. This study utilizes a novel hybrid method based on Group Method of Data Handling (GMDH) and Genetic Algorithm (GA) to design GMDH structural (GMDH-GA). Also, SingularValue Decomposition (SVD) was utilized to compute the linear coecient vectors. In order to predict the densimetric Froude number (Fr), the ratio of median diameter of particle size to hydraulic radius (d=R) and the ratio of sediment deposit thickness to hydraulic radius (ts=R) are utilized as eective parameters. Using three different sources of experimental data and GMDH-GA model, a new equation is proposed to predict incipient motion. The performance of development equation is compared using GMDH-GA and traditional equations . The results indicate that the presented equation is more accurate (RMSE = 0:18 and MAPE = 6:48%) than traditional methods. Also, a sensitivity analysis is presented to study the performance of each input combination in predicting incipient motion.
genetic algorithm (GA)
Group Method of Data Handling (GMDH)
Rigid rectangular channel
Incipient motion
Sediment transport
Storm water
2017
06
01
1000
1009
http://scientiairanica.sharif.edu/article_4083_f71e5aa91c3f919a4d3add7cb056cb59.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Fundamental period of vibration for seismic design of concrete shear wall buildings
A.
Badkoubeh
A.
Massumi
simple expression is proposed to estimate the fundamental period of vibration for concrete Shear Wall (SW) buildings. Most seismic codes specify empirical period formulas for seismic design. In this study, fundamental period data for concrete SW buildings recorded during California earthquakes between 1971 and 1994 were compared with the current US code formulas. It is shown that these formulas are inadequate for estimation of the fundamental period of concrete SW buildings. A closed-form period solution based on Rayleigh's method using SW displacement as a parameter is proposed to estimate the fundamental period of concrete SW buildings in low, moderate, and high seismicity regions. The accuracy of the closed-form solution is veried using recorded periods, and it conrms that the proposed expression provides reasonable estimates of thelower bound of a period. The results show that the fundamental period of concrete SW buildings depends signicantly on the displacement and mechanical properties of the SW.
Fundamental period
Concrete shear wall buildings
Code periods
Closed-form solution
Lower bound period
2017
06
01
1010
1016
http://scientiairanica.sharif.edu/article_4084_07d54c457ee9b05c303a31fe3e91c4b0.pdf
Scientia Iranica
Scientia Iranica
1026-3098
1026-3098
2017
24
3
Effects of petrochemical wastes incinerator ash powder instead of Portland cement on the properties of concrete
D.
Mostonejad
S.
Noorpour
M.
Noorpour
R.
Karbati Asl
V.
Sadeghi Balkanlou
A.
Karbati Asl
Petrochemical wastes incinerator ash is generated from industries in which the landfill is the last step for their flowing. This research was performed for waste management of ash and its possible large-scale utilization in making concrete. An experimental investigation carried out to evaluate the mechanical properties of concrete mixtures in which Portland cement type II was partially replaced with Petrochemical Complex IncineratorAsh Powder (PCIAP). The cement was replaced with various amounts of PCIAP, i.e. 5%, 10%, 15%, 20%, and 25%. Tests were performed on the properties of fresh concrete as well as hardened concrete. Compressive, splitting tensile and flexural strengths, and modulus of elasticity were determined in 7, 28, and 90 days. Test results indicated that by using PCIAP as partial replacement of cement, stabilization, solidication, and neutralization treatment processes for the industrial wastes management were carried out, and the testresults of the mixture M-2 (5% PCIAP) indicated that it can be used to make concrete which is lighter than normal concrete and heavier than structural lightweight aggregate concrete.
concrete
Incinerator ash
compressive strength
Splitting-tensile strength
Flexural strengths
Elastic modulus
2017
06
01
1017
1026
http://scientiairanica.sharif.edu/article_4085_53a45a7524b5534e5b47c4289c09e57c.pdf