This paper addresses the ambient vibration based finite element model updating of long span reinforced concrete highway bridges. The procedure includes ambient vibration tests under operational conditions, finite element modeling using special software and finite element model updating using some uncertain parameters. Birecik Highway Bridge located on the 81stkm of Şanlıurfa-Gaziantep state highway over Fırat River in Turkey is selected as a case study. Because of the fact that the bridge is the sole in this part of Fırat, it has a major logistical importance. The structural carrier system of the bridge consists of two main parts: Arch and Beam Compartments. In this part of the paper, the beam compartment is investigated. Three dimensional finite element model of the beam compartment of the bridge is constituted using SAP2000 software to determine the dynamic characteristics analytically. Operational Modal Analysis method is used to extract dynamic characteristics of the beam compartment by using Enhanced Frequency Domain Decomposition method. Analytically and experimentally identified dynamic characteristic are compared with each other and finite element model of the beam compartment of the bridge is updated by changing of some uncertain parameters such as section properties, damages, boundary conditions and material properties to reduce the differences between the results. It is demonstrated that the ambient vibration measurements are enough to identify the most significant modes of long span highway bridges. Maximum differences between the natural frequencies are reduced averagely from %46.7 to %2.39 by model updating. Also, a good harmony is found between mode shapes after finite element model updating.

This paper presents a numerical model based on  the explicit finite difference method for contaminant transport under electrokinetic remediation process. The effect of adsorption, precipitation and water auto-ionization reactions were considered  to  set of algebraic equations. Also the effect of electrolysis reaction in anode and cathode cells was considered with appropriate boundary conditions. The model predictions are compared with experimental results of electrokinetic lead removal from kaolinite in the literature. The coefficient of determination and index of agreement between the lead concentration of experimental result and model prediction was 0.974 and 0.884, respectively. The coefficient of determination and index of agreement between the pH value of  the experiment and the pH prediction was 0.975 and 0.976, respectively

In this article, general procedures for vulnerability assessment and retrofitting of a generic seismically designed bridge are outlined and the bridge’s damage criteria for blast resistance are explained. The generic concrete bridge is modeled and analyzed with the finite element technique implemented in ANSYS LS-DYNA environment and explosion threats are categorized into three main levels. Uncoupled dynamic technique is adopted to apply the blast loads on the bridge structure, damage and performance levels are resulted based on quantitatively verified damage mechanisms for the bridge members. The results show that, amongst different loading scenarios, the explosions that happen under deck are more critical comparing to blasts initiating from over deck sources. Furthermore, two retrofitting methods 1) concrete filled steel tube (CFST) and 2) concrete jacket are applied on the bridge columns. The program AUTODYN is used with coupled dynamic analysis of a column to compare the effectiveness of each method. Afterward, more efficient method for a column is applied to the whole bridge and its efficiency is revaluated. It is shown that CFST can decrease concrete spall, scabbing, rotation, displacements and shear forces more than the concrete jacket. Considering the proposed damage and performance levels, the bridge retrofitted with CFST reacts with lower damage level and higher performance level to blast loads.

In this study, the usage of the Level of Service (LOS) concept, which was developed specifically for pedestrian satisfaction and safety, was critically analyzed. The focuses of this investigation were the Fruin and Highway Capacity Manual (HCM) LOS values, which were evaluated and compared in terms of their anthropometric dimensions. In this paper, new LOS values are proposed on the basis of the critical evaluation of the HCM and Fruin LOS values revealing the inconsistencies between the LOS values and the analysis. The importance of emptiness area in calculating human comfort and satisfaction in terms of the anthropometric dimensions and LOS value is also discussed. A software program called Laborer Image Analysis Software (LIAS) was developed to evaluate and compare the impacts of different body dimensions on the LOS values and on the space requirements for pedestrians. LIAS is presented as a facilitation tool for calculating more concise and effective emptiness areas and LOS values. The comfort area concept is also presented and discussed. This discussion is used to reveal the contrasts and inconsistencies in the existing usage of the LOS concept and to highlight the importance of the emptiness area approach. The paper presents a different perspective and discussion on the existing utilization of LOS levels, particularly for pedestrians in different structures. The research contributes to the LOS analysis discussion in terms of the anthropometric scale according to changing user profiles and develops facilitator(s) for analyzing and applying amendments to pedestrian needs, which can be used in transportation buildings.

Steel bridges play a very important role in every country’s transportation system. To ensure that bridges perform reliably, engineers monitor their performance which is referred to as Structural Health Monitoring (SHM). An important element of SHM includes the prediction of service life. There is ample historical evidence that bridge damage is pervasive and their life time is decreasing. To manage costs and safety, service life prediction of bridges is necessary. We present a statistical method to predict service life for steel bridges. A nonparametric statistical model based on the bootstrap method for stress analysis for fatigue life prediction of steel girder bridges is proposed. The bootstrap provides a simple approach for reproduction of the probability distribution of measured strain data. The bootstrap is sensitive to the number of events in the verification sample (data), thus we introduce a stable survival distribution function (SDF). An index is presented in this paper for inferring the service life of steel bridges, which can be known as the Life Index (µ). The life index function shows variation of the age of steel bridges under daily traffic loads. A regression model is developed which relates the service life of steel bridges using a bridge life index based on measured operational strain time histories. The predicted remaining service life derived from the model can contribute to effective management of steel bridges. The proposed method assists bridge engineers, bridge owners, and state officials in objective assessment of deteriorated bridges for retrofit or replacement of deteriorated bridges. Timely repair and retrofit increase the safety levels in bridges and decrease costs.

The seismic performance levels are discrete damage states selected from among the infinite spectrum of possible damage states that buildings could experience as a result of earthquake response. The observation of building damage during strong motion earthquakes showed that correlation of structural damage with a single parameter such as peak ground acceleration or the total seismic duration is low while peak ground acceleration is often used as a main seismic parameter to evaluate seismic performance of structures. Main objective of this study is to determine the relationship between several seismic acceleration parameters and the Target Displacement (TD) of steel frame structures, which is an important parameter to identify performance levels. For this purpose, first, nonlinear analysis is performed on the SAC 3- and 9-story frames subjected to several far-field earthquakes and then target displacements and seismic parameters are calculated for each structure.The relationship between the target displacement and seismic parameters is evaluated in the form of correlation coefficient. It is shown that PGA has poor correlation with the target displacement. On the other hand, HOUSNER intensity, spectral pseudo-acceleration, spectral pseudo-velocity and peak ground velocity exhibit strong correlation with TD.

From practical point of view, optimum design of structures under time variable loadings faces many challenges. Issues such as time-dependent behavior of constraints and the computational costs of the gradients could be mentioned. In order to prevent such difficulties, in this paper, response spectrum method has been utilized instead of applying direct time history method. Additionally, seismic design of structures is defined as a design for a specific response spectra not for an individual acceleration time history. Furthermore, here, in order to guarantee the global optimal designs, the obtained results from gradient-based method are compared with those from the discrete optimization technique (Genetic algorithm). As well, the P-Delta effects are considered in a seismic analysis. In addition, many practical constraints according to the Iranian national building code (NBC) are included in the optimization problem. The developed MATLAB based computer program is utilized to solve the numerical examples of low, intermediate and relatively high-rise braced and un-braced steel frames.

Most of the proposed methods for obtaining the free vibration natural frequency of the retaining wall have been presented, assuming the behavior of the wall in two-dimensional domain, and they are not able to express the three-dimensional behavior of these structures in a satisfying manner. In this paper, the plate theory is employed to analyze the free vibration of wall-soil system in three-dimensional domain. So the retaining wall is modeled as a clamped-free plate and the stiffness of the soil existing behind the wall is modeled as a set of springs. Using the approximate Rayleigh method, new analytical expression for obtaining the free vibration natural frequencies for the three first modes of the wall is represented. The results of the proposed model are compared with both the results of the other researchers and the ones from finite element method (FEM). They are also compared with the results of a full-scale experiment and it shows a good agreement. The comparison shows that modeling the wall in two-dimensional form is not accurate enough to calculate all the natural frequencies of the wall. The results of this paper show that there is a considerable difference between two- and three-dimensional behavior of the walls. The proposed method also gives the free vibration natural frequencies of the wall extensional modes with an acceptable accuracy. Finally, the effect of tensile and compressive behavior of the soil on the fundamental frequency is studied. This research can be considered as a new field in three-dimensional calculation of the retaining walls.

An experimental program was carried out in order to investigate the usability of recycled coarse aggregate (RCA) concrete with and without ground granulated blast furnace slag (GGBFS). The RCA was derived from concrete having compressive strength of 47.6 MPa. Twelve concrete mixtures having various RCA (0-25-50-100%) and GGBFS (0-30-60%) replacement levels were designed with a water-to-binder (w/b) ratio of 0.50. Fresh concrete properties were observed through workability and slump loss. Compressive strength, tensile splitting strength, bond strength, ultrasonic pulse velocity, water absorption and density of hardened concretes were also determined at 7 and 28 days and the relations between physical properties and mechanical properties of RCA concretes with/without GGBFS were investigated. The RCA content significantly improved the tensile splitting strength of the concrete according to the compressive strength and the use of 60% GGBFS content in RCA concrete had a marginal increasing effect on the tensile splitting strength. The mixes containing 100% RCA was found to be noticeably beneficial in terms of the bond strength and the highest bond strengths were obtained with the use of 60% GGBFS content in RAC for all series at 28 days. However the lowest density and the greatest water absorption was obtained for RAC and an inverse relationship between the density and the water absorption ratio was determined.

Bridges normally undergo nonlinear deformations during a near field strong ground motion resulting in a critical deviation of their columns from the plumb state due to considerable residual deformations. These excessive residual deformations make a bridge, which has not collapsed, ‘irreparable’ and in turn ‘not operable.’ Therefore, reasonable prediction of these types of bridge piers deformations is of great importance in order to evaluate the serviceability of bridges subjected to a seismic scenario. Conventional hysteresis models formulated for typical concrete columns are normally used for this purpose which most of times fail to correctly predict the residual deformations occurred as a result of a one-sided or directivity pulse excitation. The present research aims at development of a peak oriented hysteresis model being able to regenerate residual deformations more reasonable compared to the conventional hysteresis models. This multi linear peak oriented model considers strength deterioration in each half cycle in addition to stiffness degradations in unloading cycles. Yielding points differ in both positive and negative sides of the hysteresis model that enables us to define a different elastic stiffness of both sides in asymmetric concrete sections. Another remarkable property of this model is breaking points and strength deterioration in unloading and reloading stages. This work also compares the obtained results to the conventional hysteresis models, namely bilinear, Clough, Q-Hyst, Takeda and Bouc-Wen in terms of prediction of residual nonlinear deformations in cyclic or dynamic analysis of reinforced concrete single-column bridge piers. The obtained results prove higher relative accuracy of the proposed model.

The study presents a model for the evaluation of construction projects from the point of view of the investor. The problem lies in choosing the best solution from the point of view of many criteria. The proposed model is based on a multi-criteria comparative analysis using fuzzy logic. The first part of the paper presents a selection of criteria describing the construction project along with their description. The set of attributes describing the analyzed object was determined on the basis of the synthesis of specific proposals for the parameters of construction projects. The set of criteria has been divided into two groups: technical, technological and organizational criteria and separately the economic criteria. Then, the number of variables describing the observations was checked using principal component analysis (PCA). Course of action was presented in the event of multiple criteria analysis using the fuzzy set theory. Both the weights and the evaluations of individual criteria were modelled using membership functions due to the fact that when describing a construction project, or the validity of the criteria of describing variables, they are approximate. An analysis of the correlation of selected project criteria was presented. The proposed decision support model of assessing a construction project makes possible to compare various variants based on 11 factors identified. The use of fuzzy logic has enabled more accurate description of the phenomenon analysed when the exact parameters of the project in the planning and preparation stage of the project are not known.

In this study, a comparison is made between force and displacement controlled non-linear FE analyses for an RC beam in flexure with partially developed steel bars. An FE model with slightly unsymmetrical reinforcement was analyzed by applying two-point loading using both force and displacement controlled methods. The responses obtained using ANSYS-13 were validated against available experimental data. Combined comparative display of flexural response of the beam using force and displacement controlled analysis, that has least been addressed in the literature, is given here. Study choses large-deformation-nonlinear plastic analysis scheme, discrete modeling approach for material modeling and program-chosen incremental scheme following Newton-Raphson method. The results show that displacement controlled approach is efficient in terms of time saving and less disk space requirement along with the ability to give falling branch of load-deflection response, if element displacement capacity still exists. Moreover, it gives an early estimate of the load carrying capacity of the structural element along with suitable values of convergence and non-linear solution parameters. However, for a beam with unsymmetrical detailing, force controlled analysis method seems to yield more realistic and practical results in terms of mid span deflection and beam cracking behavior compared with assumed symmetric displacement controlled technique. It also gives true fracture prediction at ultimate load level, which is not true for the displacement controlled method as the computer code forces the model to maintain equal displacements at two load points, falsely increasing the capacity of the beam.

In this paper, the probabilistic seismic performance of vertically irregular steel buildings, considering soil-structure interaction effects, is evaluated. Various irregular distributions of structural properties, including mass, stiffness and strength along the height of three-dimensional moment resisting steel frames were intended. The finite element model of soil medium was created with solid elements below the structure. The nonlinear material behavior of soil was considered as well. Nonlinear incremental dynamic analysis was performed to evaluate the flexible-base structural performance in the framework of probabilistic performance-based earthquake engineering. According to the median curves of intensity-demand of structures, it is concluded that non-uniform height-wise distribution of lateral resistance properties of steel structures varies the displacement demand and the seismic capacity of the irregular frames, compare to the regular structure. The capacity variation of most irregular frames is more obvious at the nonlinear phase of structural behavior. Due to the foundation flexibility, the damage concentration raises in the bottom floor and the irregularity increase the seismic demands of the lower floors of the system. Among all the irregular steel frames, the average increase of the displacement demand and reduction of the seismic capacity are maximal for the strength and concurrent variation of stiffness and strength irregularity models, respectively. Additionally, mass irregularity shows minor influence in the seismic demand and capacity variations of the steel frames. The predominant influence of stiffness and strength irregularities (soft and weak story) is observed in reduction of the structural ductility factor and the mean annual frequency of exceeding limit states.

This paper presents a comparative numerical research on the overall seismic behavior of RC frames with different types of rebars (normal versus high strength rebar). A nonlinear numerical model is developed and is validated using experimental results. Comparing the numerical and experimental behaviors shows that the developed model is capable of describing the hysteretic behavior and plastic hinges development of the experimental RC frames with various strength longitudinal steel bars. The validated model is then used, considering the influences of axial load ratios and volumetric ratios of longitudinal rebars of column, to investigate the effects of reinforcement strength on the overall seismic behavior of RC frames. The simulation results indicate that utilizing high strength reinforcement can improve the structural resilience, reduce residual deformation and achieve favorable distribution pattern of plastic hinges on beams and columns. The frames reinforced with normal and high strength steel bars have comparable overall deformation capacity. The effect of axial load ratio on the energy dissipation, hysteretic curves and ultimate lateral load of frames with different strength rebars is similar. In addition, increasing the volumetric ratios of longitudinal rebars can increase the ultimate lateral load of frame and improve the plastic hinge distribution of frame.

For years, coupling shear walls have been used in  the mid to high-rise buildings as a part of lateral load- resisting system mostly, because of their ability to control the displacement of structures, Recently by changing the design codes from strength based design to performance based  design, nonlinear behavior of coupled walls became important for practical engineers, so that many researchers  are looking for ways to improve and also predict the behavior of coupled walls under severe earthquakes. This paper  presents  the results of   linear,  nonlinear static ( pushover)  and  nonlinear inelastic time-history analysis  of a 10-story  two- dimensional coupling shear wall (CSW) which is perforated with 3 different patterns which are taken from considering  the S22 stress of shell elements used for modeling shear walls,  nonlinear static analysis results confirm that perforation can increase the response modification  factor of coupled walls up to 33 percent and also the results of  linear analysis and design indicate that perforation can reduce the amount of reinforcement of coupling beams and other frame's  structural components. Also results of nonlinear inelastic time history  analysis confirm that by using perforation patterns the base shear- roof displacement hysteretic response get better and the  systems with perforation patterns can absorb more energy under severe earthquakes.

The present paper addresses the comparative study of two adjacent single-degree-of freedom structures for elastic and inelastic systems with and without pounding and also in the presence and absence of TMD under seismic excitations. The tuned mass damper considered for the present study is a passive device attached to single main structural unit in the form of weak storey at the top of main system. Total eight models have been considered depending upon the presence and absence of pounding as well as TMD in the analysis. The entire numerical simulation is carried out in time domain by considering the inputs of four real earthquake ground motions. An elastic adjacent structural system always overrates the pounding forces than the inelastic adjacent structural units. The use of TMD reduces the pounding forces in the adjacent structures. In pounding, structural displacement response is much sensitive for inelastic systems mostly under consideration or ignorance of TMD. Structural energy formation in the adjacent structures shows much variation with and without consideration of pounding as well as TMD.

Minimum reinforcement ratios provided in the standards are remaining at very low levels especially at large systems subject to the effects of earthquake. Thus, arranging the reinforcement ratios intended for preliminary design can provide significant ease and safety in project design phase, and speed and simplicity in the project control phase. Moreover, a more realistic limitation becomes ensured compared to general minimum reinforcement ratios given in the standards. System characteristics which may affect the reinforcement ratios can be specified by general and simple parameters. As the result of many extensive studies, expressions for reinforcement ratios intended for preliminary design which will cover systems having different parameters can be composed. Today, thanks to the development levels of finite elements programs which can perform reinforced concrete modeling, meeting this requirement is much more possible compared to the past. Structure of parameters should neither be very special nor very general. Otherwise, reinforcement ratios intended for preliminary design will either be valid for a single system or they will remain at very low limits such as the minimum reinforcement ratios given in the standards. For this reason, in this study it was tried to follow a route in between these two extreme conditions. Today, it is possible to perform many studies on the systems having different and comprehensive inclusive parameters and to determine practical ratios which will constitute a recommendation for the project designs. For this purpose, an eight storey reinforced concrete system with single spacing whose shear wall cross-section is 25x250cm, column cross-section is 25x30cm, and beam cross-section is 25x50cm was addressed, and its non-linear planary analyses under static earthquake loads were performed through the ANSYS finite elements program for 13 different reinforcement case. The reinforcement ratios to be recommended for the addresses system and similar systems were tried to be revealed. The examined system was arranged as to get the most critical and extreme values for many parameters which can be considered, but it was tried for the reinforcement ratios to be recommended to be valid not only for this system but also for the general system network having similar properties to this system. In the future researches, expressions of general and inclusive preliminary design reinforcement ratios can be obtained as per the results of many studies to be made on systems having different parameters.

One of the main concerns in an essential or highly important building is finding the appropriate structural system, while the efficiency of each conventional structural system varies in different cases. In this paper a new multi objective structural configuration is proposed and its efficiency for protecting buildings against the multi-hazards including earthquake, explosion and typhoon is shown in a case study of a 10 stories building sample. To create the optimum and efficient configuration of the structural elements, and to make some large spans, a configuration including Vierendeel girders is used. In this type of configuration, the inner suspended floor parts protect the outer elements by balancing perimeter span loads. This system makes a new condition for the building to be protected against the progressive collapse due to the terrorism attacks. Furthermore, the partially suspended floors in special stories act like tuned mass dampers (TMDs), which are suitable to decrease the amplitude of the displacement response of the structure during an earthquake.

During the entire life cycle of a pavement, highway agencies are expected to maintain adequate surface frictional properties to facilitate traction between car tires and pavement surface. Traditionally the repair method for a friction-deficient pavement surface is the application of a new surfacing layer. The monitoring and remedying practice is important however, it is a passive approach toward the problem. A more proactive approach would be to test the hot mix asphalt in the laboratory during its initial mix design stage to ensure that aggregate combinations used in the asphalt pavement will provide adequate friction over the life of the pavement. Toward this objective the polishing behavior of laboratory-prepared HMA specimens made of eight different job mix formulas has been studied in terms of friction values. In addition, a robust statistical analysis of the obtained surface friction values has also been carried out in an attempt to verify the success in developing this new asphalt polisher that is used to simulate the tire-pavement interaction. Furthermore, polishing behavior (i.e., polishing trend, rate of friction loss and absolute and percent values of decrease) were all fully investigated to capture surface frictional deterioration of HMA specimens. In conclusion, the new asphalt polisher showed a good degree of repeatability. Additionally, it has been concluded that the decrease in polish number is maximum during the first hour of polishing. With the passage of time the drop in friction decreases and stabilizes.

In recent times, Bus Arrival Time Prediction (BATP) systems are gaining more popularity in the field of Advanced Public transportation systems (APTS), a major functional area under Intelligent Transportation Systems (ITS). BATP systems aim to predict bus arrival times at various bus stops and provide the same to passenger’s pre-trip or while waiting at bus stops. A BATP system, which is accurate, is expected to attract more commuters to public transport, thus helping to reduce congestion. However, such accurate prediction of bus arrival still remains a challenge, especially under heterogeneous and lane-less traffic conditions such as the one existing in India. The uncertainty associated with such traffic is very high and hence the usual approach of prediction based on average speed will not be enough for accurate prediction. In order to make accurate predictions under such conditions, there is a need to identify correct inputs and suitable prediction methodology that can capture the variations in travel time. To accomplish the above goal, a robust framework relying on data analytics is proposed in this study. The spatial and temporal patterns in travel times were identified in real time by performing cluster analysis and the significant inputs thus identified were used for the prediction. The prediction algorithm used the Adaptive Kalman Filter approach, in order to take into account of the high variability in travel time. The proposed schemes were corroborated using real-world GPS data and the results obtained are very promising.