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Civil Engineering Infrastructures Journal - Volume:55 Issue: 1, Jun 2022

Civil Engineering Infrastructures Journal
Volume:55 Issue: 1, Jun 2022

  • تاریخ انتشار: 1401/03/22
  • تعداد عناوین: 12
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  • Mohammad Mohammadizadeh *, Farnaz Esfandnia Pages 1-17
    There are several methods to predict the compression strength of reinforced concrete columns confined by FRP, such as experimental methods, theory of elasticity and plasticity. Meanwhile, due to its good potential and high accuracy in predicting different problems, the soft computing techniques has attracted considerable attentions. Soft computing includes methods and programs to deal with complex computational problems. The objective of this study is to evaluate and compare the performance of four methods of Least Squares Support Vector Machine (LS-SVM), the Weight Least Squares Support Vector Machine (WLS-SVM), Adaptive Neuro-Fuzzy Inference System (ANFIS) and Particle Swarm Optimization - Adaptive Network based Fuzzy Inference System (PSO-ANFIS) for predicting the compression strength of reinforced concrete columns confined by FRP. A total of 95 laboratory data are selected for use in these methods. The Root Mean Square Error (RMSE) and the correlation coefficient of the results are used to validate and compare the performance of the methods. The results of the study show that the PSO-ANFIS method with the RMSE of 4.610 and the coefficient of determination of R2 = 0.9677 predicts compression strength of reinforced concrete columns confined by FRP with high accuracy and therefore, it can be a good alternative to time-consuming and costly laboratory methods.
    Keywords: ANFIS, Compression Strength, FRP-Confined Columns, LS-SVM, PSO-ANFIS, WLS-SVM
  • Jafar Sobhani *, Meysam Najimi, A. Pourkhorshidi Pages 19-29

    The current study aims to investigate influence of w/cm ratio, cementitious materials content and supplementary cementitious materials on the transport properties of concrete and chloride-induced corrosion rate of reinforcement. To do this, several mixes are designed with and without silica fume and natural zeolite as supplementary cementitious materials, w/cm of 0.4 and 0.5, and cementitious materials contents of 325 and 400 kg/m3. These mixes are subjected to evaluation of compressive strength, transport properties (i.e. absorption, water penetration depth and rapid chloride penetration test), and corrosion rate measurement through Potentiodynamic test and electrochemical measurements. The results of this study reveal that there is not strong correlation between corrosion rate of reinforcement and the measured strength and transport properties. The corrosion rate of reinforcement significantly decreased through reduction of water-to-cementitious materials ratio and use of supplementary cementitious materials; of which w/cm showed a more considerable influence. Increase in cement content, however, increased the transportation of water and chloride into the concrete and thus increased the corrosion rate of reinforcement.

    Keywords: Concrete, Corrosion, Silica Fume, Transport Properties, Zeolite
  • Ehsan Dehghani *, Maryam Soltani Mohajer Pages 31-41
    In the Second World Conference on Disaster Risk Reduction (WCDRR) the concept of resilience has been presented as an Effective Strategy to improve post-earthquake conditions. One of the principles of resilience is “quick response”, which requires having relevant information to determine the level of vulnerability of the city. For this purpose, many studies have been done in recent years to investigate the seismic behavior of a variety of infrastructures in a city. The fragility curve is one of the most popular tools among researchers to investigate the probabilistic seismic behavior of structures. It expresses the degree of structural vulnerability by indicating the exceedance probability of damage versus the given level of ground shaking. In this study, 24 fragility curves are developed for four typical intermediate Reinforced Concrete Moment Resistant Frame structures in Qods town (located in Qom, Iran) with two number of stories (4 and 8) and two number of bays (1 and 2). They are derived through nonlinear incremental dynamic analysis in one and two horizontal directions under two sets of near-field and far-field ground motion records. The results indicate that the seismic response of structures is the same for uni-directional and bi-directional analyses. Also, it seems that the response of the structures with periods greater than 1 sec is in correlation with the mass-to-stiffness ratio. Change in the width and number of bays of the structure does not affect the probability of failure, as far as the width to the number of bays ratio remains constant. Furthermore, the probability of failure is higher when the structure is subjected to near-field earthquake ground motion records.
    Keywords: Damage Evaluation, Fragility Curve, Incremental Dynamic Analysis, Reinforced Concrete Moment Resistant Frame, SAP2000
  • Chenna Rajaram *, Ramancharla Pradeep Kumar Pages 43-58
    An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. It ruptured 340 km along three faults namely, the Susitna Glacier, Denali and Totschunda faults in central Alaska. The earthquake was recorded at 23 stations in Alaska and the Peak Ground Acceleration (PGA) of 0.32g was recorded at station PS10, which was located 3 km from the fault rupture. In this study, strike-slip Denali fault has been considered for studying the characteristics of ground motions through modified semi-empirical approach. The ground motion records of the 2002 Denali earthquake are generated through MATLAB code. The results revealed that modified semi-empirical approach is fairly good in agreement with observed ground motion records at all stations. A perfect match is observed between Fourier amplitude spectra of simulated and observed ground motions at PS09 and CARLO stations. A good match is observed between elastic response spectra of observed and simulated ground motions.
    Keywords: Denali Earthquake, Fourier Amplitude Spectrum, Ground Motion Prediction Equation, Synthetic Accelerogram
  • Iman Abbasi Nattaj Omrani, Azizollah Ardeshir-Behrestaghi *, Ali Saeedian Pages 59-74
    Polyvinyl alcohol is one of the most efficient synthetic fibers in concrete technology; however, the size effect was rarely evaluated in Polyvinyl alcohol fiber-reinforced concretes. In this research, six types of SCC mixtures containing two dosages of PVA fibers were designed in two strength levels and different sizes of cylindrical specimens were cast. The fresh properties, 28-day compressive strength, and pre-peak energy per unit volume of PVA-FRSCC were evaluated through laboratory tests. several theoretical models, including Size Effect Law, Modified Size Effect Law, Multi-fractal Scaling Law, and Sim et al. model, were also refined to study the size effect in the designed mixtures under uniaxial compressive failure. Based on the obtained results, the inclusion of Polyvinyl alcohol fibers had significant effect on the performance of the designed concretes. The incorporation of PVA fibers reduced the specimen size effect and improved the ductility and pre-peak energy absorption of plain SCC.
    Keywords: compressive strength, Energy Absorption, Polyvinyl Alcohol Fiber, Self-Consolidating Concrete, Size effect
  • Amir Talebi, Ali Derakhshani * Pages 75-87
    P-y analysis approach is among the most widely used methods implemented for simulating the pile behavior under lateral loading. To obtain the p-y curve of a pile group, that of a single pile should be modified by a group reduction factor which is conventionally determined by the pile spacing to diameter ratio and the pile row number in the group. The pile section types and soil characteristics i.e. internal friction angle are among other important factors affecting the group reduction factor. However, the influence of these parameters has not been investigated in previous researches, thoroughly. In this study, continuum models of eight pile groups with different conditions regarding pile section types and soil properties were built and analyzed. It was found that the group reduction factor of the pile group with square tube section is less than that of the group of piles with pipe sections, due to group effects. On the other hand, for the pile groups of both section types, the greater internal friction angle, increases the shadowing and edge effects which results in lower group reduction factor. Moreover, the group reduction factors calculated based on numerical modeling results were compared with the recommendations of AASHTO and FEMA guidelines. It was also shown that the continuum model results conform with the results of experimental studies.
    Keywords: Group Reduction Factor, Internal friction angle, Pile Group, P-y Curve, Section Properties, Soil-Pile Interaction
  • AliReza Ghanizadeh *, Nasrin Heidarabadizadeh, Vahid Khalifeh Pages 89-108

    This research aim is to develop a procedure for backcalculation of flexible pavements moduli based on the hybridization of the Artificial Neural Network (ANN) and the Jaya optimization algorithm. The ANN was applied to predict the pavement deflection basin, and the Jaya was employed for moduli backcalculation. The comparison of hybrid ANN-Jaya procedure with some backcalculation software indicates the high ability of the developed method to perform backcalculation of flexible pavements moduli. The comparison of the computational speed and accuracy of hybrid ANN-Jaya with ANN-PSO and ANN-GA indicates the superior performance of ANN-Jaya compared to other methods.

    Keywords: artificial neural network (ANN), Backcalculation, Falling Weight Deflectometer (FWD), Flexible Pavements, Jaya Optimization Algorithm
  • Alireza Haji Hossein, Hamidreza Bigdeli, Fardad Mokhtari, Sepehr Jahantab, Asghar Habibnejad Korayem * Pages 109-120
    In this paper, the feasibility of employing amorphous carbon powder as a viable degradation inhibitor for cement mortars made with siliceous aggregates was investigated. Amorphous carbon powder is a by-product of the paraffin industry and was replaced by 0, 4, 6 and 8% of aggregate. Mechanical strength, rheology and water absorption were analyzed considering three common physical factors of concrete namely strength, workability and durability. Mechanical properties of mixtures were obtained using flexural and compressive strengths and rheological attributes were collected through flow table test. Results revealed that adding amorphous carbon powder to the bulk cement mortar could enhance the strength and durability of cement mortar. Replacing 8 wt.% of siliceous aggregate dust filler by amorphous carbon powder caused an increment about twofold in the 28-day compressive strength and reduction of the flow table results by about 20% compared to those of the control mixture. Moreover, hydrophobicity and impermeability properties of amorphous carbon -modified cement mortars, resulted in reduced moisture susceptibility.
    Keywords: Amorphous carbon, Cement Composites, durability, Permeability
  • Majid Moradi *, Hamidreza Tavakoli Pages 121-137
    Post-earthquake fire is a rare event with catastrophic consequences. The occurrence of fire after an earthquake can cause a catastrophe. Structural damage during earthquake loading affects the capacity of the element in the fire following earthquake loading. In this study, the probability of collapse and collapse time probability of a 4 story RC frame under earthquake and post-earthquake fire loading are assessed. At first structural sections are modeled in ABAQUS and heat transfer analysis is performed in them. After the results extraction of heat transfer analysis, the frame is modeled in openSees software base on the Finite Element method. For assessment seismic collapse probability, Incremental Dynamic Analysis (IDA) is conducted and the fragility curve is extracted for three performance levels. Then, seismic and fire loading are applied to frame consecutively and collapse probability is calculated. The probability distribution functions and the cumulative distribution function of the structural collapse time are calculated in the post-earthquake fire analysis. The results show that increasing PGA increases collapse probability and decrease collapse time in the RC frame under post-earthquake fire loading.
    Keywords: Collapse Time, Heat transfer, Post-Earthquake Fire, Probability Assessment, RC Frame
  • MohammadKazem Bahrani *, Amin Nooralizadeh, Mahdy Sharify, Najmeh Karami Pages 139-160

    Bridges are critical highway structures, and damage to them can result in the loss of vital lifelines. Many bridges reaching the end of their expected lifespans should have their seismic performance evaluated immediately. The study utilized a 1/3 scale model of two-column bridge bents developed within the last 20 years that split from the deck under cyclic loads. The purpose is to investigate seismic performance and define performance levels utilizing experimental observation. The damage estimates from previous studies for each performance level were reviewed and, where necessary, revised. Damage and performance levels for joints were estimated differently than for other components such as cap beams and columns, according to the findings. The present study proposes new performance levels including joint damage. The overall seismic performance of the concrete bridge bents revealed that the anticipated mechanisms did not occur, but that flexural hinges formed in the joint region rather than in the columns, as required by current codes.

    Keywords: Concrete Pier, Cyclic Loading, damage, Performance level, Seismic performance
  • Amir Nohekhan, Amir Samimi *, Sara Zahedian Pages 161-181
    This paper explores the transferability of the Multiple Discrete-Continuous Extreme Value (MDCEV) model for activity type and duration using various transfer methods and sample sizes. This study employs the data of travel demand studies in two major cities, Shiraz and Mashhad in Iran. The model is first developed for Shiraz and then transferred to Mashhad. The adopted transfer methods are transfer scaling, Bayesian updating, combined transfer estimation, and joint context estimation. Aggregate and disaggregate transfer measures are adopted to examine the transferred models' general prediction and policy predictability. The results indicate the joint context estimation method's superiority in terms of estimation and policy prediction powers. The available massive data to the authors enabled measuring the value of sample size in this study. The sample size sensitivity analysis revealed a decrease in the marginal gain of the transferred model's performance as the sample size increases. Remarkably, the transferred model outperforms even the locally estimated model when 1) advanced transfer techniques are applied (i.e., the combined transfer estimation and the joint context estimation), and 2) the application context sample size is large enough (i.e., more than 30 percent).
    Keywords: Bayesian Updating, Combined Transfer Estimation, Joint Context Estimation, MDCEV Model, Model Transfer, Spatial Transferability, Transfer Scaling
  • Abed Kordi, Mussa Mahmoudi * Pages 183-194
    In recent years, damage detection has been an important issue in the condition assessment of structures. This research presents a new method for the detection of damaged members in truss bridges under moving load using the time history response and influence line curves of the members. For this reason, two different Finite Element (FE) models of truss bridges under moving load with different damage scenarios have been investigated. The damaged members are detected by adapting the difference curve shape of displacement responses obtained from the intact and damaged models to the axial force influence line curve shape of these members. The results demonstrate that when a member of a truss bridge is damaged, the difference curve of displacement responses is similar in shape to the influence line curve of the damaged member. It should be noted that the proposed method can accurately diagnose the damaged members with the displacement response of only one desired point of the truss bridge.
    Keywords: Damage Detection, Displacement, Influence Line Curve, Moving Loads, Truss Bridge