Investigation of crack propagation behavior of impact-resistant functionally graded
concrete
safa
peyman
دانشگاه جامع امام حسین (ع)/ تهران
author
pouya
heydari digesara
School of Civil Engineering, University of Tehran, Tehran, Iran
author
text
article
2020
per
This paper conducted research on numerical studies of fracture mechanics related to crack propagation of projectile impact-resistant functionally graded concrete consisting of plain, fiber reinforced and tough aggregate concrete layers, which are presented by modeling a three-point bending test in presence of initial notch. To consider fracture behavior in process zone, a bilinear softening model for plain and tough aggregate concrete and a trilinear softening model obtained from traction-separation relationship of cohesive zone model is used. Extended finite element method is utilized for numerical analysis. result of numerical modeling of three-point bending test have been investigated and compared using loading versus crack mouth opening displacement (P-CMOD) curves. Functionally graded model has been studied in comparison with homogeneous plain, fiber reinforced and tough aggregate concrete models, and the results showed that homogeneous fiber reinforced concrete model has a better fracture behavior than others models. The functionally graded model has not been subjected to sudden failure in comparison with plain and tough aggregate concrete models due to the fiber reinforced in end layer. Also, effect of each layer and their thickness change in the functionally graded model are evaluated and it was observed that fiber reinforced layer due to high fracture energy created by fiber bridging has a beneficial effect on the fracture behavior related to other layers. In this way, by considering proper position and thickness for this layer, in addition to providing appropriate performance in the fracture behavior, cost of materials also be significantly reduced.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1111
1128
https://ceej.aut.ac.ir/article_3002_54698d7fa2a9353edf63058009ff08f4.pdf
dx.doi.org/10.22060/ceej.2018.14226.5618
Prediction models for estimation of exit hydraulic gradient and uplift pressure under
the influence of downstream filter
میثم
نوری
دانشگاه تبریز
author
Farzin
Salmasi
tabriz university
author
Javad
Parsa
Tabriz University
author
text
article
2020
per
This study investigates the impact of filter which is located in downstream of the hydraulic structures for reduction of uplift pressure and hydraulic gradient. Effective parameters for design of filter are: length of filter (L), distance from downstream of structure (X) and upstream water head (H). The outcomes of this study showed that design of filter with L/H equal to 0.057, results 60% reduction of downstream uplift pressure and 10% reduction of upstream uplift pressure. Thus the effect of filter in uplift pressure in downstream of floor is impressive. By increasing the filter length, exit hydraulic gradient always decreases and with increasing the distance of downstream (X), the effect of filter in reduction exit gradient increases. Design of filter with L/H equal to 0.057 have a good impact on exit hydraulic gradient reduction (65%), witch by increasing the length of filter, hydraulic gradient reduction will be reduced. Finally, regression and artificial intelligence models (RBF, MLP and SVM) were used for prediction of uplift pressure and exit hydraulic gradient in structure with filter. Comparison of these models base on two error measurements (R2, RMSE and MAE) demonstrated that regression model is a suitable model and SVM as a poor model in prediction of uplift pressure and hydraulic gradient.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1129
1144
https://ceej.aut.ac.ir/article_2992_155d4459d5af76b89081fbd7faa8feed.pdf
dx.doi.org/10.22060/ceej.2018.14461.5661
Experimental study of the effect of adding clay nanoparticles to improve strength
properties of contaminated clayey-sand soil with gasoil
Milad
Shahidi
Master Graduate of university of Zanjan
author
Farhang
Farrokhi
Department of Civil and Environmental Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran
author
Farhad
Asemi
Master Graduate of university of Zanjan
author
text
article
2020
per
The release of oil pollutants in the soil causes changes in the structure, texture and the relationship between the soil particles. This has destructive effects on the physical and mechanical properties of soils. In recent years, improvement of degraded engineering properties of these soils for their use in construction projects has been a challenge for researchers and engineers. In this paper, the effect of adding two types of clay nanoparticles on the improvement of mechanical properties of Clayey Sand contaminated with gas-oil has been investigated. For this purpose, after determining the basic properties of natural soil, soil with 6% and 8% gas-oil, contaminated soil stabilized with nano-clay in values of (0.5, 1, 2 and 3%) and organo-clay in values of (0.3, 0.5, 0.7 and 1%), standard compaction and unconfined compressive strength tests during the two curing periods (7 and 28 days) were performed on them. Scanning electron microscopy (SEM) was also used to evaluate the microstructure of natural soil samples. Also, the microstructure of natural soil, contaminated soil and contaminated soil stabilized with nanoparticles was studied with the help of SEM. The results of the tests showed that maximum dry density, optimum water content, and unconfined compressive strength have decreased in the soil with gas-oil. The stabilization of contaminated soil using clay nanoparticles showed that adding 2% of nano-clay to contaminated soils of 6 and 8% of gas-oil resulted in the highest increase in compressive strength of 58% and 56%, respectively. In addition, adding 0.7% organo-clay to soil containing 8% of gas-oil leads to an increase of 37.56% in compressive strength. It was also observed that the addition of nano-clay and organo-clay to the contaminated soil resulted in an increase in optimum water content and a decrease in the maximum dry density. In general, it can be concluded that the contaminated soil with gas-oil has the potential to improve strength properties by adding clay nanoparticles.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1145
1162
https://ceej.aut.ac.ir/article_2953_7aeae49520848d2c6735b47a284f0e47.pdf
dx.doi.org/10.22060/ceej.2018.14287.5612
Evaluating the Rheology Properties of Self-Consolidating Concrete Using the Plate
Test Method
ali akbar
shirzadi javid
assistant professor, school of civil engineering, iran university of science and technology
author
Parviz
Ghoddousi
iran university of science and technology
author
mohammad
jaberizadeh
Iran university of science and technology
author
behnam
bozorgmehr
Iran University of Science and Technology
author
text
article
2020
per
Setting time and thixotropy of self-consolidating concrete (SCC) mixtures are two important parameters that affect the early age properties. In order to determine these parameters, there are traditional methods that have advantages and disadvantages such as low accuracy or high cost of testing. The aim of this study is introducing an acceptable method (called plate test) of determining setting time and thixotropy of SCC mixtures. The proposed method is including a rough plate immersed in fresh mixture from one side and attached to the accurate scale from another side. In this study the thixotropy of different self-consolidating concrete mixtures (SCC) containing silica fume and slag were tested. Results of the thixotropy obtained from the plate test were compared with the results obtained from penetration resistance and rheometer respectively. Results showed that the mixture containing slag produced the less temperature comparing with the mixture containing silica fume. It was also shown that the amount of thixotropy obtained from the plate test had a difference of 4% up to 10% in comparison with the rheometer and the results of the setting time had also shown a maximum difference of 9% compared with the results of penetration resistance test. The results proved that the plate test has an acceptable accuracy and can be recommended.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1163
1176
https://ceej.aut.ac.ir/article_2952_5cd7015606aa41da21e2a3083fbc53cc.pdf
dx.doi.org/10.22060/ceej.2018.14305.5619
Structural system identification of elevated steel water tank using ambient vibration
test and validation of numerical model
Mohammad
Alembagheri
دانشگاه تربیت مدرس
author
text
article
2020
per
The present research aims to investigate the feasibility of using ambient vibration tests for system identification of elevated water tank. To this end, the elevated water tank located in Tarbiat Modares University (TMU) campus is utilized. The tank is instrumented with a sensitive velocimeter sensor and the ambient velocity of the tank is recorded for 30 minutes in three perpendicular axes. The amplitude of the velocity signal reaches to about 30 mm/s. Using the peak picking method, the fundamental frequency of the tank is determined about 1.9 Hz. Although, considering the non-perfect symmetry of the tank and the misaligned orientation of the sensor, the obtained values in two lateral directions differ 5%. Then, the numerical model of the tank is prepared in software and calibrated. In the primary modeling, the values of natural frequencies of the tank are in good agreement with the results of the ambient vibration data. It shows the calibration of the numerical model which can be used in the assessment of the seismic behavior of the elevated water tank.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1177
1186
https://ceej.aut.ac.ir/article_2951_740fa132ac733d21c52c5dbd1a42eacd.pdf
dx.doi.org/10.22060/ceej.2018.14331.5625
Mashhad Subsidence Monitoring by Interferometric Synthetic Aperture Radar
Technique
Mohammad
Khorrami
Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
Saeed
Abrishami
Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
author
Yasser
Maghsoudi
Department of Photogrammetry and Remote Sensing, Faculty of Geodesy and Geomatics Engineering, K. N. Toosi University of Technology, Tehran, Iran
author
text
article
2020
per
Deep groundwater withdrawal in Mashhad, one of the largest municipalities in Iran, caused severe land subsidence. Land subsidence in this area can be destructive for urban infrastructures and can create serious environmental issues and structural damages. The main aim of this research is to precisely determine the vertical ground deformations in Mashhad to evaluate and compare the current situation with the previous reports on this area. For this purpose, we have applied Persistent Scatterer Interferometric Synthetic Aperture Radar technique to complement previous works by using more accurate data and procedure in the interested urban area. Furthermore, we considered geotechnical properties which were not focused in the previous studies. For this purpose, 69 descending and ascending C-band radar images, provided by relatively high-resolution Sentinel-1A satellite, were used to estimate the deformation-trend. The method was applied to the images from October, 2014, to February, 2017. The assessment procedure demonstrated a high-rate of subsidence in northwest of Mashhad with the significant deformation of 140 mm/year. The outputs were validated using in-situ measurements data and hydraulic head variations respecting piezometric data extracted from groundwater wells. Subsequently, the geotechnical properties of the chosen area were considered to interpret the results. The results of this study illustrated that the land subsidence in the case study is brutally continuous in most areas and there is no sign of decrease in the amount of deformation rate.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1187
1204
https://ceej.aut.ac.ir/article_3019_58533165c387c6bc4fb614d5346cf2ba.pdf
dx.doi.org/10.22060/ceej.2018.14300.5617
Effect of Filler Type on Moisture Susceptibility of Asphalt Mixtures by Successive
Freeze-Thaw Cycles and Comparing Results with Components of Surface Free Energy
Fereydoon
Moghaddasnezhad
Department of Civil Engineering and Environmental, Amirkabir University of Technology
author
Mohammad
Arbabpour Bidgoli
School of Civil and Environmental Engineering, Road and Transportation Engineering, AmirKabir University of Technology, Tehran, Iran
author
Koorosh
Naderi
Department of Civil Engineering and Environmental, Amirkabir University of Technology
author
Seyedeh Zahra
Mirtabar
Department of Civil Engineering and Environmental, Amirkabir University of Technology
author
text
article
2020
per
Based on the important effects of filler on performance-related properties of asphalt mixtures, this study investigates the influence of filler type on moisture susceptibility of asphalt mixtures under multiple freeze-thaw cycles. Furthermore, the effect of changing the type of mineral fillers, especially replacing fillers with recycled concrete materials on moisture resistance of asphalt mixture, with sustainable development approach, is evaluated. In this study, first, the indirect tensile strength and the resilient modulus tests are conducted following 1, 3, 6, and 10 cycles of freeze-thaw and then the fracture energy is calculated through the results of indirect tensile test. Next, the surface free energy components of mastics with different types of filler are calculated using the static contact angle measurement method. The results of performance-based moisture susceptibility tests showed that replacing natural filler with Portland cement can result in the best performance compared to control mixture, limestone filler, and RCA filler. However, the evolution of mechanical properties of control filler, limestone filler, and RCA filler depends on the number of freeze/thaw cycles. At higher conditioning cycles, TSR values demonstrate a different behavior such that the TSR values of the asphalt mixture containing RCA filler increase up to 15% on average compared to the asphalt mixture containing limestone filler after the first cycle. Although the results of mechanical properties in initial freeze-thaw cycles are similar to surface free energy results. However, these results cannot predict the behavior of asphalt mixtures at higher freeze-thaw cycles.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1205
1220
https://ceej.aut.ac.ir/article_2938_d229c9e3e13d2d5e802fca65e2e3a304.pdf
dx.doi.org/10.22060/ceej.2018.14396.5643
Recovering the Temporal Release Rate of Pollutant Sources in the River in Two dimensional and real condition
siamak
amiri
water structures engineering department, agriculture faculty, Tarbiat Modares university, Tehran, Iran
author
مهدی
مظاهری
هیات علمی دانشگاه تربیت مدرس
author
jamal
mohammad vali samani
water structures engineering department, agriculture faculty, Tarbiat Modares university, Tehran, Iran
author
text
article
2020
per
Over the past three decades, many approaches and methods have been investigated based on the inverse problem solving to recover the temporal release rate of pollutant sources, especially in groundwater. But, number of studies is limited about the rivers; therefore, developing a method which can determine temporal release rate of pollutant sources in the river precisely and at the same time be able to consider the conditions of the flow and bed is promising. In the present study, the inverse solution of the advection-dispersion equation for recovering the temporal release rate of pollutant sources leads to the solution of a linear overdetermined system of equations type of ill-posed problem. Therefore, in this research a numerical model based on the inverse matrix approach based on the Tikhonov regularization method and the results of the superposition principle has been applied to the recovery of the temporal release rate of pollutant sources and the exact time of release of the pollutant from the source. The model has been designed to retrieve the complexity time of multiple pollutant sources in a complex state. Also, the model has been verified using real two-dimensional data of Ohio River located in the United States. Finally, a general and practical framework has been introduced to apply in real condition. Eventually, the computational results were showed that, the inverse model can recover the temporal release rate of pollutant sources using the lowest field and downstream data containing high error rate at each point of the river.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1221
1240
https://ceej.aut.ac.ir/article_3077_d10e42de1406c3d449f23f724545166c.pdf
dx.doi.org/10.22060/ceej.2018.14503.5675
Strengthening Optimization of RC Columns with Rectangular Section by FRP
Wrapping
Kourosh
Nadimi Shahraki
Islamic Azad University KhomeiniShahr Branch
author
Mohammad
Reisi
Islamic Azad Univiersity, Khomeinishahr branch
author
text
article
2020
per
Wrapping reinforced concrete (RC) column with FRP sheets improves compressive strength of concrete. Since stress-strain curve of concrete confined with FRP is different from stress[1]strain curve of normal concrete, equations presented by codes for design and analysis of normal (unstrengthened) RC column and based on stress-strain curve of normal concrete cannot be used for design and analysis of columns strengthen with FRP. In this research, first by using stress-strain curve of confined concrete presented by researchers and ACI code, an algorithm was designed to determine axial and flexural capacity of strengthened column and implemented in Visual C# environment. Verification of this work was investigated and confirmed by comparing it with experimental results. The programming was developed in a way that it could be used to optimize the design. Thus, by specifying required information including cross sectional dimensions, number and diameter of rebars, applied axial load and bending moment on column, FRP sheet properties and price, the performed programming can determine which type of FRP, if used, while providing the required flexural and axial capacity , has also the minimum price.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1241
1260
https://ceej.aut.ac.ir/article_3015_7429200e31db7072010d43bf10a87fb1.pdf
dx.doi.org/10.22060/ceej.2018.14493.5672
Design and construction of inclined plane device for modeling the interface interaction
of geo-synthetic layers
Payman
Shaykhi
Department of Civil Engineering, Arak Branch, Islamic Azad University, Arak, Iran
author
seyed hamid
LAJEVARDI
دانشگاه آزاد اسلامی اراک
author
text
article
2020
per
One of the important applications of geo-synthetics in the earth’s slopes, such as landfills and waste disposal areas, is to use them as liner system. Proper assessment of the interaction of geo-synthetics at slopes, such as landfill, is an important issue in preventing the slip and instability of the slopes. The inclined plane is a suitable method for assessing the interaction between the geo[1]synthetics interacting in a sloping and tilted state under low normal stresses. The European Standard EN ISO 12957-2 provides a “standard displacement” for estimating the geo-synthetic interface’s friction angle. In this paper, inclined plane device, which for the first time in Iran was completely designed and constructed, describes the technical characteristics of the device and prepares the sample. This apparatus has the ability to perform experiments to investigate the interaction of soil-soil, soil/geo-synthetics and geo-synthetic/geo-synthetic interfaces at low normal stress. Experiments are carried out on geo[1]membrane and geotextile types to investigate the interaction of their surface. By changing the type of geo-synthetics, it was observed that friction angle of geo-synthetic interfaces is not constant and depends on the type of geo-membrane and the woven or non-woven geo-textile. The geo-membrane/geo-textile interface is the least amount of geo-membrane with hard polyethylene, and the highest amount is used when polyvinyl chloride is used.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1261
1276
https://ceej.aut.ac.ir/article_3024_f2f04d1bf5f356b01187aedb6a4917fc.pdf
dx.doi.org/10.22060/ceej.2018.14276.5611
Evaluating Pavement Roughness Based on Vibration Analysis Due to Road Health
Monitoring System
Mohammad
Arbabpour Bidgoli
School of Civil and Environmental Engineering, Road and Transportation Engineering, AmirKabir University of Technology, Tehran, Iran
author
Amir
Golroo
Transportation group, Civil dept, AUT
author
Ali
Ghelmani Rashidabad
MSc Student, Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran
author
Amir Abolfazl
Suratgar
Electrical Eng Faculty, amirkabir University of Technology
author
Mohammad Azam
Khosravi
Assistant Professor, Department of Electrical Engineering, Amirkabir University of Technology, Tehran, Iran
author
text
article
2020
per
The implementation of an efficient pavement management system is dependent on the acquiring desired information from the pavement condition. The automatic data collection is welcomed by mechanized systems due to adequate precision and speed. However, the various systems are developed that have high construction and operation costs. Therefore, the development of cost-effective devices that is independent from the vehicle vibrations and equipped with instrumentation is necessary. In this study, the health monitoring system is developed as a system of longitudinal profile measurement and road roughness evaluation based on response-type vehicle with applying the accelerometers, distance meter, geographical positioning system. Upon harvesting of the vibration response of the health monitoring system and the vehicle, data preparation and signal filtration are performed through the digital signal processing techniques. Therefore, the dynamic equations governing on the behavior of the health monitoring system are derived based on one degree of freedom. The dynamic parameters of system are extracted based on optimization approach using the genetic algorithm and the particle swarm optimization algorithm. Afterwards, the extracted longitudinal profile based on the vibration responses is became to the longitudinal profile with the specific speed by the developed algorithm which is set by the relationship between speed and frequency of harvested data. Then, the International Roughness Index is calculated from the longitudinal profile of the studied pathway by ProVal software. Accuracy of the health monitoring system results is validated by manual method with measuring of the error percentage average and the root mean square error normalized between the outputs of the system and the Road Surface Profiler with values of 19.72% and 9.68% respectively. Finally, evaluation of the repeatability and the obtained results from the validation output indicates accuracy and significant quality of the road health monitoring system.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1277
1296
https://ceej.aut.ac.ir/article_2894_9e5ce95ee12e0125468116acb8da3406.pdf
dx.doi.org/10.22060/ceej.2018.14136.5569
Interaction of axial, shear and bending loads in buckling behavior of pierced and nonpierced long steel plates
Amin
Yazdi
Amirkabir University of Technology
author
Mohammad
Alembagheri
دانشگاه تربیت مدرس
author
text
article
2020
per
Nowadays, there is a spread use of plates for various purposes because of their good performance and economic advantages. Hence, it seems that it is necessary to investigation the plate behavior. In this study buckling behavior of long plates under the combination of bending, shear and axial loads are studied using the finite element method. The effect of boundary conditions of the long plate under the combination of loads is considered. The effects of adding holes to the long plates are also considered. The holes have various radii with a unique array. The behavior of load intersection in non-pierced and pierced plates is compared. The loading consists of bending, axial and shear which all of them are in-plane and are applied to the plates’ edges. For this purpose, more than 1000 models were created. For the investigation, two of the loads are applied to the plate and the load bearing capacity of the third load is calculated. Results showed that long plates under axial load have less sensitivity to holes in comparison with the shear and the bending loads. The holes with diameters equal to or less than 0.06 of plate’s width can hardly influence the buckling behavior.
Amirkabir Journal of Civil Engineering
Amirkabir University of Technology
2588-297X
51
v.
6
no.
2020
1297
1312
https://ceej.aut.ac.ir/article_3001_1db2ec732c0f7f3f9d08823ec2d4f777.pdf
dx.doi.org/10.22060/ceej.2018.14483.5668