Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
A synopsis about the effect of metakaolin on the durability of Portland cement – An overview
579
603
EN
Alaa M.
Rashad
Building Materials Research and Quality Control Institute, Housing & Building National Research Center, HBRC, Cairo, Egypt
alaarashad@yahoo.com
Metakaolin (MK) produced by suitable thermal treatment of either kaolin or paper sludge. MK can be used to modify some properties of Portland cement (PC) system. Many authors studied the effects blended PC with MK on durability characteristics. The current investigation focuses on, to review, the effect of MK on the durability of blended PC. A review on resistance of abrasion, fire, freeze-thaw, seawater, chloride-ion diffusion, carbonation, acid, sulfate, chloride, corrosion, creep, shrinkage, alkali-silica reaction (ASR) and near surface is presented.This overview can be considered as a short guide for Civil Engineers.
Portland cement,Fire resistance,Freeze-thaw resistance,chloride-ion diffusion,chemical resistance,carbonation resistance,Durability
http://scientiairanica.sharif.edu/article_1888.html
http://scientiairanica.sharif.edu/article_1888_4275c00e87e752c2c1d69441d00ac885.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Nonlinear Behavior of Concrete End Diaphragms in Straight Slab-Girder Bridges
604
614
EN
Himan
Hojat Jalali
Department of Civil Engineering, Sharif University of Technology, Tehran, P.O. Box 11155-9313, Iran
Shervin
Maleki
Department of Civil Engineering, Sharif University of Technology, Tehran, P.O. Box 11155-9313, Iran
smaleki@sharif.edu
The seismic behavior of concrete end diaphragms of bridges has not been studied before and there are no significant design provisions available. According to the American Association of State Highway and Transportation Officials (AASHTO), the end diaphragms being part of the seismic load path have to remain elastic under the prescribed seismic design forces, regardless of the type of bearings used. In this paper, using a three-dimensional finite element model and nonlinear time history analyses the behavior of reinforced concrete end diaphragms in straight single-span slab-girder bridges has been investigated. The results are compared to AASHTO’s design provisions. It is concluded that for slab-girder concrete bridges the concrete diaphragms remain elastic under design earthquake loading. It is also concluded that AASHTO’s recommended seismic design force for end diaphragms could be unsafe in most cases.
Bridge,seismic analysis,Reinforced Concrete,diaphragms,elastomeric bearing
http://scientiairanica.sharif.edu/article_1889.html
http://scientiairanica.sharif.edu/article_1889_5ff10acc707976d02216670833ce1e68.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Nonlinear Finite Element Analysis of Rectangular Reinforced Concrete Slabs Strengthened by Fiber Reinforced Plastics
615
628
EN
Cindrawaty
Lesmana
Department of Civil Engineering, Maranatha Christian University, Bandung 40164, Indonesia
Hsuan-Teh
Hu
Department of Civil Engineering, National Cheng Kung University, Tainan 701, Taiwan
hthu@mail.ncku.edu.tw
Strengthening reinforced concrete members by bonding fiber reinforced plastics on the tension face has become viable alternative to address strength deficiency problems. This paper investigates rectangular composite slabs subjected to distributed load using Abaqus finite element software. A parametric study using appropriate constitutive models is generated to stimulate the nonlinear material behavior of reinforced concrete and FRP. The numerical analysis examines the behavior and maximum capacity of composite slabs. The paper presents the finite element analysis results for concrete slabs strengthened with FRP material. The proposed fitted equation is applicable in preliminary investigation for engineering applications.
Finite element analysis (FEA),Reinforced Concrete,Laminates,Slab,Numerical analysis,Strengthened
http://scientiairanica.sharif.edu/article_1890.html
http://scientiairanica.sharif.edu/article_1890_959120f76f5cfdea707080eac7eca855.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Pile head displacements with different cross sectional shapes under lateral loading and unloading in granular soils
629
638
EN
Pejman
Vahabkashi
Department of Civil Engineering, Amir Kabir University of Technology, No. 209, Faculty of Civil Eng., 424, Hafez Ave., Tehran, Iran
vahabkashi@aut.ac.ir
Alireza
Rahai
Department of Civil Engineering, Amir Kabir University of Technology, No. 611, Faculty of Civil Eng., 424, Hafez Ave., Tehran, Iran
rahai@aut.ac.ir
Piles in structures’ foundations, which are used to load transmission from main structure to bed, are generally subjected to lateral loads. In order to study the effect of concrete pile geometry on its structural behavior, several models with different shapes and dimensions were selected and analyzed assuming the nonlinear behavior for soil. The behavior of pile models were studied, evaluated, and tabulated using numerical analysis in different conditions such as: changes in pile geometry and shape and soil properties. Therefore, the displacements of piles` head situated in granular soil with different compaction levels under a lateral load were studied in loading and unloading cycles. The dissipated energy was calculated based on pile head displacements in different load steps in the first and second cycles of loading. The "performance index" is defined as the ratio of dissipated energy to the maximum pile head displacement to compare these two factors effect on different pile models' behavior concurrently. It was observed that piles with rectangular cross sections and smaller width, have the maximum dissipation of energy and the minimum displacement occurs in dense soil.
Soil–pile interaction,Lateral load,Loading and unloading,Pile head displacements,Cross sectional shapes,Dissipated Energy
http://scientiairanica.sharif.edu/article_1891.html
http://scientiairanica.sharif.edu/article_1891_a928078ada8298de67c4e748a3437877.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Development of Nonlinear Transfer Matrix Method for Inelastic Analyses of Beams
639
649
EN
Minho
Kwon
Dept. of Civil Engineering, ERI, Gyeongsang National University, South Korea
Minho
Kwon
Dept. of Civil Engineering, ERI, Gyeongsang National University, South Korea
kwonm@gnu.ac.kr
Jinsup
Kim
Dept. of Civil Engineering, ERI, Gyeongsang National University, South Korea
Jinsup
Kim
Dept. of Civil Engineering, ERI, Gyeongsang National University, South Korea
jskim0330@gmail.com
Hyunsu
Seo
Dept. of Civil Engineering, ERI, Gyeongsang National University, South Korea
Suchart
Limkatanyu
Dept. of Civil Engineering, Faculty of Engineering, Prince of Songkla University, Thailand
The objective of this study is to develop a material-nonlinear-analysis algorithm based on the transfer matrix method (TMM). This newly developed algorithm can be used to perform nonlinear analyses of continuous beam systems. The nonlinear transfer matrix is derived from the general frame stiffness matrix and the Gauss-Lobatto integration scheme is employed for numerical integration. In the TMM, the system equation has a constant number of system unknowns regardless of the total degree-of-freedom number in the structure and the system response (either linear or nonlinear). As a result, TMM can be used efficiently both for linear and nonlinear structural analyses. In this study, a secant nonlinear algorithm required in nonlinear TMM is employed due to its good compromise between the convergence rate and numerical stability. To verify accuracy and efficiency of the developed TMM, four numerical examples are selected and analyzed. The analysis results are compared with those obtained by the highly accurate flexibility-based frame model in terms of global and local responses.
Material Nonlinear,stiffness matrix,TMM (Transfer Matrix Method),Nonlinear Analysis,Beam Model
http://scientiairanica.sharif.edu/article_1892.html
http://scientiairanica.sharif.edu/article_1892_5c0f105cfda9d22aef38db36c160080f.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Bi-Level Optimization of Resource-Constrained Multiple Project Scheduling Problems in Hydropower Station Construction under Uncertainty
650
667
EN
Zhe
Zhang
School Economics & Management, Nanjing University of Science and Technology, Nanjing 210094, P. R. CHINA
Jiuping
Xu
bState Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University; Uncertainty Decision-Making Laboratory, Sichuan University, Chengdu, 610065, P. R. CHINA
Hui
Yang
School Economics & Management, Nanjing University of Science and Technology, Nanjing 210094, P. R. CHINA
Yang
Wang
National Key Laboratory of Air Traffic Control Automation System Technology, Sichuan University; College of Computer Science, Sichuan University, Chengdu, 610065, P. R. CHINA
The aim of this paper is to deal with the resource-constrained multiple project scheduling problems (RCMPSP), which consider the complex hierarchical organization structure and fuzzy random environment in the decision making process. A bi-level multiobjective RCMPSP model with fuzzy random coecients is presented by taking into account the strategy and process in the practical RCMPSP. In the model, the project director is considered as the leader in the upper level, who aims to minimize total tardiness penalty of all sub-projects and the consumption of resources. Meanwhile, the sub-project manager is the follower in the lower level, regards the target to minimize the duration of each sub-project. To deal with the uncertainties, the fuzzy random parameters are transformed into the trapezoidal fuzzy variables first, which are de-fuzzified by the expected value index subsequently. A multiobjective bi-level adaptive particle swarm optimization algorithm (MOBL-APSO) is designed as the solution method to solve the model. The results and analysis of a case study are presented to highlight the practicality and eciency of the proposed model and algorithm.
Bi-level Programming,fuzzy random variables,resource-constrained scheduling problem,multiple projects,Multi-objective optimization,Particle swarm optimization
http://scientiairanica.sharif.edu/article_1893.html
http://scientiairanica.sharif.edu/article_1893_f428d0ac21a21ce17aa9fe0c0318200e.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Integrating system dynamics and fuzzy bargaining for quantitative risk allocation in construction projects
668
678
EN
Farnad
Nasirzadeh
Dept. of Civil Engineering, Faculty of Engineering, Payame Noor University, Tehran, Iran
f.nasirzadeh@gmail.com
Mehdi
Rouhparvar
Department of Project Management and Construction, Science and Research Branch, Islamic Azad University, Tehran, Iran
mehdi.rouhparvar@gmail.com
Hamed
Mazandarani Zadeh
Dept. of Technical- Engineering, Imam Khomeini International University, Qazvin, Iran
hzadeh@iust.ac.ir
Mahdi
Rezaie
Dept. of Civil Engineering, Iran University of Science and Technology, Tehran, Iran
mahdirezaie@gmail.com
Quantitative approaches to risk allocation have been developed to overcome the limitation of qualitative approaches and to determine how the responsibility of risk should be shared between contracting parties. This paper integrates a system dynamics simulation scheme with fuzzy bargaining game theory for quantitative risk allocation. The behaviour of contracting parties in the quantitative risk allocation negotiation process is modelled as players' behaviour in a game. A system dynamics based model is employed to determine the contractor and client costs (players' payoffs)at different percentages of risk allocation. Having determined the players' payoffs, the common interval between the players' acceptable risk allocation percentages is determined. The bargaining process is then performed between two parties accounting for the common interval and a desirable and equitable percentage of risk allocation is determined.
Quantitative risk allocation,Bargaining game theory,system dynamics,Fuzzy Logic,Negotiation
http://scientiairanica.sharif.edu/article_1894.html
http://scientiairanica.sharif.edu/article_1894_b8188ecf7ce83639dfde357bfebf822f.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Measuring wave velocity, damping and stress-strain behaviors of geo-materials using GAP-SENSOR
679
698
EN
A.
Aghaei Araei
Department of Geotechnical Engineering, Road, Housing and Urban Development (BHRC), Tehran, P.O. Box 13145-1696, Iran
A.
Aghaei Araei
Department of Geotechnical Engineering, Road, Housing and Urban Development (BHRC), Tehran, P.O. Box 13145-1696, Iran
xmszgnzq@scientiaunknown.non
I.
Towhata
Geotechnical Engineering Group, Department of Civil Engineering, University of Tokyo, 7-3-1 Hongo Bunkyo-ku, Tokyo, P.O. Box 113-8656, Japan
S.
Hashemi Tabatabaei
Department of Geotechnical Engineering, Road, Housing and Urban Development (BHRC), Tehran, P.O. Box 13145-1696, Iran
cokbmyoj@scientiaunknown.non
H.R.
Razeghi
School of Civil Engineering, Iran University of Science and Technology (IUST), Tehran, P.O. Box 16765-163, Iran
S.
Hashemi Tabatabaei
Department of Geotechnical Engineering, Road, Housing and Urban Development (BHRC), Tehran, P.O. Box 13145-1696, Iran
A triaxial testing system is described for measuring the wave velocity, stiness, damping and stress-strain behavior of layered granular materials and rock specimens under impact, cyclic and monotonic loading. The system is equipped with high-frequency GAPSENSORs (GSs) in front of target plates connected on the side of a specimen surface to measure wave velocity, axial and radial deformations locally, LDTs to measure axial and radial deformations locally, and a load cell. Based on the rst arrival of compressional wave of the deformation time-histories under impact loading, the pulse velocity is evaluated. In addition, using a reduced deformation amplitude technique at dierent elevations of the specimen, damping ratio is calculated. Results indicate that measurement of the wave velocity and damping ratio using low noise level GSs is a simple, nondestructive and reproducible method. Comparing the results of small strain shear modulus and damping ratio using local axial and radial strains measured by LDTs and GSs in the cyclic loading, with those of the proposed method, the high precision of the used innovative method is conrmed. Using this system, a continuous stress-strain relation for a strain range of 0.0001% to several % can be obtained fro a single test using a single specimen.
Wave velocity,modulus,damping,Monotonic,Dacite,Mudstone,Tire chips,Toyoura
http://scientiairanica.sharif.edu/article_1895.html
http://scientiairanica.sharif.edu/article_1895_7c7861852fad58ad59e2bbd370de3c6e.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Shear-Torsion Interaction of RC Beams Strengthened with FRP Sheets
699
708
EN
Sayed Behzad
Talaeitaba
Department of Civil Engineering, Isfahan University of Technology, Isfahan, Islamic Republic of Iran
talaeetaba@iaukhsh.ac.ir
Davood
Mostofinejad
Civil Eng. Department, Isfahan University of Technology, Isfahan, Islamic Republic of Iran
dmostofi@cc.iut.ac.ir
One of the most common options for structural strengthening and rehabilitation is the use of FRP sheets for shear-torsion strengthening of reinforced concrete beams (RCBs). Their widespread use owes much to their ease of application in addition to many other advantages. The availability of technical references and construction codes today make it easy to calculate the shear and torsion capacities of strengthened beams. Practically, however, it is the combined shear and torsion rather than pure torsion that develops in beams. The present article investigates the use of FRP sheets in strengthening RC beams. For the purposes of this study, 14 RC beams were used that were classified into three different sets: one set consisted of 5 non-strengthened (plain) beams and two sets (one with 5 and the other with 4 beams) consisted of RC beams strengthened with CFRP sheets in two different strengthening patterns. The shear-torsion interaction curves were derived for them by loading the beams under a variety of eccentricities ranging from 0 (pure shear) to infinity (pure torsion). The supports were constructed with flexure and torsion rigidity. Laboratory tests revealed that the shear-torsion interaction curves for all the three sets of beams were close to straight lines.
Interaction curve,reinforced concrete beams,Combined shear-torsion,FRP sheets,Strengthening
http://scientiairanica.sharif.edu/article_1896.html
http://scientiairanica.sharif.edu/article_1896_64de19568ca0752a715726a78e3e90e6.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Extent of riprap layerwith different stone sizes around rectangular bridge piers with or without an attached collar
709
716
EN
M.
Karimaee Tabarestani
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
A. R.
Zarrati
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
zarrati@aut.ac.ir
M. B.
Mashahir
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
E.
Mokallaf
Department of Civil and Environmental Engineering, Amirkabir University of Technology, Tehran, Iran
In the present study, extent of riprap layer with different sizes around bridge piers is investigated. Rectangular piers with or without an attached protective collar aligned with the flow and skewed at different angles are tested. The optimal configurations of riprap extent for each pier condition with different sizes are determined. Experiments showed that in case of aligned rectangular pier without a collar only 8% of the area around the pier is critical and the remaining 92% area can be protected with about 60% smaller riprap stones. As the skew angle of the pier increases up to 20o, the critical area increases up to 23% of the riprap extent. In case of protected pier with collar, the collar prevents the critical region around the pier in aligned and 5o skewed pier. However, by increasing the flow attack angle up to 20o, only a small area up to 30% in the riprap extent around the collar is critical and the remaining area can be placed with 40% smaller riprap size. Finally, the design algorithm for riprap extent with different sizes is presented.
Local scour,Rectangular bridge pier,Critical region,Riprap extent,Collar,Riprap sizing
http://scientiairanica.sharif.edu/article_1897.html
http://scientiairanica.sharif.edu/article_1897_67346995878c5820efbfbf8a625b086d.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
Multi objective optimization of orthogonally stiffened cylindrical shells using optimality criteria method
717
727
EN
Ghazaleh
Eslami
Department of Civil Engineering, AmirKabir University of Technology, Tehran, Iran
Mohammad Z.
Kabir
Department of Civil Engineering, AmirKabir University of Technology, Tehran, Iran
mzkabir@aut.ac.ir
A multi objective optimality criteria (OC) is used to obtain optimum design of metal cylindrical shells under combined external loading. The objectives are to maximize the axial and hoop stiffness and minimize the mass of stiffened cylinders subject to the constraints including functions of weight and buckling load in such a way that the stiffened shell has no increase in the weight and no decrease in the buckling load with respect to the initial unstiffened shell. The optimization process contains six design variables including shell thickness, number of circular ring stiffeners, number of longitudinal stringer stiffeners, height of ring stiffeners, width of ring stiffeners, and longitudinal stiffeners eccentricity from shell's centerline. In analytical solution, the Rayleigh–Ritz energy procedure is applied and the ring stiffeners are treated as discrete elements. The shapes of the ring and stringer stiffeners are assumed as rectangular and Z, respectively. The shell is subjected to the uniform axial and non-constant external pressure, simultaneously. The longitudinal stringers are placed in equal spacing, whereas, the rings can be placed in unequal space due to non-constant of external pressure over the cylinder length. The results show that the iteration numbers depends on the ring stiffener space states.
Multi objective optimization,Stiffened cylindrical shell,Optimality criteria,ring stiffeners,stringers stiffeners
http://scientiairanica.sharif.edu/article_1898.html
http://scientiairanica.sharif.edu/article_1898_71597b462f026dcbeecb1c0dd4b8c4a7.pdf
Sharif University of Technology
Scientia Iranica
1026-3098
2345-3605
22
3
2015
06
01
A seismic slope stability probabilistic model based on Bishop's method using analytical approach
728
741
EN
A.
Johari
Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
johari@sutech.ac.ir
S.
Mousavi
Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
A.
Hooshmand nejad
Department of Civil and Environmental Engineering, Shiraz University of Technology, Shiraz, Iran
Probabilistic seismic slope stability analysis provides a tool for considering uncertainty of the soil parameters and earthquake characteristics. In this paper, the Jointly Distributed Random Variables (JDRV) method is used as an analytical method to develop a probabilistic model of seismic slope stability based on Bishop's method. The selected stochastic parameters are internal friction angle, cohesion and unit weight of soil, which are modeled using a truncated normal probability density function (pdf) and the horizontal seismic coefficient which is considered to have a truncated exponential probability density function. Comparison of the probability density functions of slope safety factor with the Monte Carlo simulation (MCs) indicates superior performance of the proposed approach. However, the required time to reach the same probability of failure is greater for the MCs than the JDRV method. It is shown that internal friction angle is the most influential parameter in the slope stability analysis of finite slopes. To assess the effect of seismic loading, the slope stability reliability analysis is made based on total stresses without seismic loading and with seismic loading. As a result two probabilistic models are proposed.
Reliability,Jointly distributed random variables method,Monte Carlo simulation,Seismic slope stability,Limit equilibrium method
http://scientiairanica.sharif.edu/article_1899.html
http://scientiairanica.sharif.edu/article_1899_5597f0b014b5b80bfc2f11d556f93c5d.pdf