Concrete flat roof defects such as water leakage present a significant and common problem in large building, particularly in tropical countries, where rainfall is high. To monitor this condition, effective non-destructive test methods are required to detect problems at an early stage, especially hidden defect within the concrete roof, which are critical. This paper presents the potential use of electromagnetic (EM) waves for determining possible leakage of the concrete flat roof as a result of failure of the waterproof membrane layer. This study was assessed, experimentally by investigation of the propagation of EM waves through the roof and their interaction with water. Novel Microwave sensors described in the paper operates in the 6 GHz to 12 GHz frequency range using a Marconi 6200A microwave test set. A range of existing current methods were overviewed and analysed. Results of experimental tests confirmed that microwaves could be used as an alternative non-destructive method for identifying water ingress caused by membrane failure into the concrete roof.

This study evaluated the effects of Warm Mix Asphalt (WMA) additives on the compaction temperature and properties of Crumb Rubber Modified (CRM) asphalt binder and mixture. Two different WMA additives (named as Sas and Evm) were used to prepare warm-mix CRM asphalt binder and mixture. The viscosity of different warm-mix CRM asphalt binders and mastics were measured at different temperatures. The rheological and mechanical properties of different warm-mix CRM asphalt binders were tested. At the mixture level, the volumetric properties of different warm-mix CRM asphalt mixtures were experimented by Gyratory compactor at different temperatures and the performance of different warm-mix CRM asphalt mixtures were evaluated. It was found that, both of the two WMA additives could lower the compaction temperatures of CRM asphalt mixtures by 10°C~20°C. However, they have different influences on rheological properties of CRM binder and performance of CRM mixture. The Sas warm-mix additive can improve the anti-rutting performance of CRM mixture but may degrade its low-temperature performance and moisture stability. The Evm warm-mix additive has no adverse effects on the high-temperature and low-temperature performance of CRM asphalt mixtures and can improve its moisture stability.

In this paper, the assessment of four short-span steel bridges from 24 to 42 m under local overloaded trucks and ground motion records are presented and discussed. Bridges were virtually located in Mexico, and so the vehicular live loads, earthquake loads due to local seismicity, and other local loads were adapted in the design. A realistic condition of the local design truck for Mexico was selected from survey traffic flows reported for local highways. Nonlinear dynamic analyses were carried out using seven historical records associated with the largest vertical intensities from subduction earthquakes in Mexico. Results are intended to evaluate the local practice, which frequently adopts the current AASHTO LRFD Specifications in the absence of an official local design code for bridge structures. Thus, this research pretends to provide design recommendations for short-span steel bridges in Mexico.

The determination of the parameters of concrete (i.e., elasticity modulus, tensile strength) is very crucial task in material engineering. For this purpose, in general, structural codes propose some empirical formulas to estimate the parameters of materials and is useful for designers rather than the experimental process. However, the estimated results usually vary for different standards. Hence, this research paper aims to compare the elasticity modulus formulas considering six standards (TS 500, ACI 318M-05, CSA A23.3-04, SP 52-101-2003, EN 1992-1-1 and AS-3600-2001) with experimental elasticity modulus test results. In the evaluation of the results, the TS 500 and EN-1992-1-1 overestimate the elasticity modulus and the SP-52-101-2003 estimates the values more close to experimental results. In addition, a new equation for modulus of elasticity including the compressive strength and the density is derived for RAC. Also, in this paper energy capacities of concretes (elastic energy capacity, plastic energy capacity and toughness) are evaluated considering compressive strength test data. As a result, according to energy capacities of concretes, the proportions 5% silica fume (SF) and 30% recycled aggregate are proposed as the optimum ratio.

The present study focuses on measuring the effects of industrial wastewater disposed from thermal electricity power plant as by-product on the geotechnical properties of sandy soil and applying washing process to remediate the contaminated soil samples and measure the efficiency of washing technique. The disturbed sandy soil samples were obtained from Al-Kufa City located to the southwest of Iraq and the industrial wastewater obtained from Al-Musayib thermal electricity power plant. The intact sandy soil was contaminated in the laboratory with four percentages of industrial wastewater (10, 20, 40 and 100%) calculated according to the weight of dry soil. The industrial wastewater is mixed with distilled water to constitute the solution used in the contamination process of soil through soaking the soil by this solution for 30 days. The study results showed that with increasing the percentages of the contaminant, there was a slight increase in both the liquid limit and particle size, while there was a significant increase in the optimum water content. Nevertheless, a slight decrease was observed in the specific gravity, maximum dry unit weight, and void ratio, while, a considerable decrease was noticed in the angle of the internal friction and coefficient of permeability of soil. The proposed remediation technique “soil washing” is efficient, economical, and time saving when used to remediate sandy soils. After remediation, the results showed an increase in the cohesion, angle of internal friction and maximum dry unit weight. Also, a slight increase was observed in the specific gravity, void ratio and permeability coefficient of remediated soil samples when compared with that of contaminated samples. The removal efficiencies of contaminant from soil were (97.63, 96.79, 96.58, and 93.87%) for the soil samples contaminated with industrial wastewater by (10, 20, 40 and 100%), respectively.

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.

To study and predict the behavior of flexible pavement over expansive soils, a pavement structure was subjected to different laboratory and fieldwork experiments. The existing pavement was replaced and designed based on California Bearing Ratio (CBR) method, with a new one, and subjected to the traffic from various number of load cycles from 12.1 up to 155.52 kcycles of standard axle load (80 kN) through dual wheel assembly over a 6-month period. As the preliminary step, the deflection measurements were taken at the asphalt surface layer, using a Total station at different distances as function of truckload applications. The numerical analysis is carried out with the Finite Element software package PLAXIS version 2012. In the new model, the calculation of the transferred pressure to the pavement through contact area of tires is 3D it was turned into a 2D problem, and the pavement was subjected to a static loading using a ratio factor of dynamic additional charge. The materials’ behavior was simulated with nonlinear models: Mohr–Coulomb (MC) for pavement layers and soft-soil model (SSM) for the expansive subgrade, in saturated drained and undrained conditions. The results indicate that displacements under static loading in saturated drained conditions and when non-linear materials are present are the closest to field measured deflections.

Soils with poor engineering properties have been a concern to construction engineers because of the need to strike a balance between safety and economy during earthworks construction. This research work investigates the effects of treating a soil having poor geotechnical properties with a bio-enzyme to determine its suitability for use as road pavement layer material. The elemental composition and microstructure of the soil was determined using energy dispersive X-ray spectroscopy and scanning electron microscopy, respectively. The specific gravity, Atterberg limits, compaction, strength and permeability characteristics of the soil was determined for various dosages of the bio-enzyme. The mountain soil is classified as clayey sand and A-2–4, according to unified soil classification and AASHTO classification systems, respectively. With increasing dosage of the bio-enzyme, the plasticity index, maximum dry unit weight and permeability of the soil decreased, while its 28-day California bearing ratio value, unconfined compressive strength and shear strength increased. Consequently, the application of bio-enzyme to the soil improved its plasticity and strength, and reduced its permeability. It, therefore, became more workable and its subgrade quality was improved for use as a road pavement layer material. The stabilized soil can be suitably used for constructing pavement layers of light-trafficked rural (earth) roads, pedestrian walkways and bicycle tracks.

The effects of effective stress and void ratio on the secondary compressibility of the sandy and clayey soils were investigated in this study. The coefficient of secondary compression of Ottawa sand in single stage and stepwise loading tests increases with effective vertical stress while that of saturated kaolinite decreases with effective vertical stress. Multi-staged loading tests showed that at a given effective stress, the higher the void ratios of the soils, the higher the coefficients of secondary compression of the soils are. It was concluded that the secondary compressibility of a soil depends on not only the effective stress, but also the void ratio of the soil. A general relationship between the coefficient of secondary compression, and effective stress and void ratio was proposed for soil. The discrepancy of the dependency of secondary compressibility on effective stress for different soils was well explained using this relationship, moreover, the quasi-overconsolidated state of clayed soil induced by time effect and the effect of surcharge preloading on the secondary compressibility of soft ground were discussed in light of the general relationship.

The correlations and relationships between electrical resistivity and geotechnical parameters of soils have become very important for site investigation. However, there is a lack of understanding about the relationships between electrical resistivity and geotechnical parameter values. The resistivity piezocone penetration tests and laboratory tests have been conducted for geotechnical investigations of marine clay in Jiangsu province of China to establish quantitative relationships between electrical and geotechnical data. The geotechnical investigation reveals that electrical resistivity values are very low for marine clay in Jiangsu, ranging from 5 to 10 Ω m. The correlations between electrical resistivity and geotechnical parameters are examined using Spearman’s rank correlation test that is a rank-based test for correlation between two variables without any assumption about the data distribution. It was shown that the electrical resistivity has strong bonds with the moisture content, void ratio, salt content and plasticity index. In terms of quantitative relationships, good fitting relationships between electrical resistivity and selected geotechnical parameters are observed. The statistical analysis indicates that the electrical resistivity is a good indirect predictor of selected geotechnical parameters. The data studied demonstrates the usefulness of the in situ resistivity method in geotechnical investigations, which have an advantage over other geotechnical methods in cost performance.

Present work is devoted to a better insight into the identification of carbonation versus efflorescence formation in alkali-activated blast-furnace slag and investigates the relation between the chemical composition of the alkali-activator and the extent of the occurrence of these two phenomena. Obtained results showed that mixes of relatively lower alkali contents suffers not only from weak compressive strength due microstructural defects, but also from carbonation during the first few days. On the other hand, mixes containing relatively higher alkali contents strongly suffers from efflorescence formation in spite of their interestingly high compressive strengths. Carbonation during the first few days can partially neutralize the alkali content of the surface layers of the material which in turn significantly affects the activation mechanism leading to the formation of binding compounds of lower degree of Si substitution with Al in the molecular structure.

The reinforced concrete bifurcation in hydropower station is consistently under high internal water pressure, and its diameter is usually larger than common duct junctions. In order to diminish or to decrease the heavy plastic zone and stress concentration, structure rounding is commonly used on bifurcation. This will bring some changes to the flow characteristic of bifurcation, and it is an interesting attempt to figure out the influence of structure rounding optimization. The Realizable k-ε model was employed in Computational Fluid Dynamics numerical simulation. The water pressure distribution was compared quantitatively at several certain sections. Furthermore, uneven pressure is analyzed by relative standard deviation. Hydraulic characteristics are discussed as well, including flow pattern, excavation volume and head loss in different working conditions. The results indicate that the pressure of pipe wall is uneven, and the maximum and minimum pressure value has a differential of 0.3% - 1.2% compared to relative static water pressure. The pressure unevenness will increase after structure rounding, and it has a positive correlation with structure rounding radius. At the same time, it is more reasonable for structure rounding in obtuse angle region than that in acute angle region, on account of well-distributed flow conditions and better economic benefit.

One kind of the irregularities in structures, with considerable effect on seismic performance, is setback in elevation that causes large damage especially in the vicinity of the irregularity. The main objective of this research is to propose and develop drift based index to estimate damage to Reinforced Concrete Moment Resisting Frames (RCMRFs) with setback. For this purpose, first, inelastic dynamic time-history analysis is performed on several frames with different types of setbacks subjected to various earthquake records and damage to them is computed by the Park-Ang damage index. Then two relations between the damage and drift are derived by applying irregularity indices to account for setback effects. It is shown that the proposed damage indices are capable to estimate the damage index of setback frames.

The motorcycle is considered as one of the most applicable transportation modes for different types of trips in Iran. According to the report by Iran Police Department in 2011, almost 25% of all crash fatalities are related to the motorcycle riders and their passengers. The objective of this study is to identify the most important factors that contribute to the fault of motorcyclists involved in crashes. This is done by using the Classification And Regression Trees (CART) model to differentiate between at-fault and not-at-fault cases. The results show that the most important factor in determining at-fault probability of motorcyclists is the collision type. According to this fact, the probability of rear-end collision is the highest, while the probability of side collisions is the lowest. The importance of other factors is variable considering the collision type. In the case of rear-end collisions, the passengers characteristics and the age of the rider are the most important factors. However, in the case of side collisions, lighting condition and area type (in both urban and rural roads) are the most important. Finally, it is suggested that, training of riders can reduce rear-end collisions as well as installing systems that warn drivers when they are close enough to motorcycles in side collisions.

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.

Stilling basins and hydraulic jumps are designers’ favorable choice for energy dissipation downstream of spillways and outlets. A properly designed stilling basin can ensure considerable energy dissipation in the short distance of a basin. In this study, experiments have been conducted to evaluate effects of a perforated sill and its position on the length of a favorable B-type hydraulic jump in a stilling basin. Perforated sills with different heights and ratio of openings were placed in different positions of the stilling basin. Tests were carried out for three tail water depths to assess the sensitivity of the jump to tail water. The hydraulic characteristics of the jump were measured and compared with continuous sill-controlled and free hydraulic jumps. Results of the experiments confirmed significant effect of the perforated sill on dissipation of energy and development of the jump in a shorter distance. Results are also presented in the form of mathematical models for estimation of the sill height, sill position, and basin length with the inflow measurable parameters of depth and velocity.

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.

This paper investigates the frequency response method for waterhammer phenomenon in piping networks. The unsteady flow governing equations are solved in time domain using the method of characteristics. They are also solved in frequency domain using the transfer matrix method. For the pipe network under consideration, critical transient excitation scenarios are identified. For each scenario, the frequency responses of the system as well as the time history of the transient pressures at the network nodes are calculated. The model is applied against a real pipe network and the results of the transfer matrix method are compared with those of the method of characteristics. It is concluded that the frequency response method not only presents a very fast algorithm for analyzing pipe systems but also, has an acceptable accuracy compared to the method of characteristics. The frequency response method requires linearization in some terms of the governing equations. Instead of that, it needs no computational discretization and interpolation necessary in time-space domains when using the method of characteristics.

Manufacturing industries synthesize new chemical products every day, which eventually find their ways into domestic and industrial wastewaters. As a result, wastewater is becoming increasingly more complex in nature. The emerging pollutants escape the treatment systems and appear in the receiving water bodies. Wastewater treatment plants in India still report effluent parameters in terms of BOD and COD at ppm level, whereas these emerging pollutants, many of whom are non-biodegradable, can be toxic and carcinogenic at ppb level. Therefore, it is imperative to look for alternatives or upgrade the existing systems which safely remove these harmful compounds from wastewater. In this research, efficiency of electrocoagulation process was assessed in a laboratory-scale setup in removing recalcitrant carbon from a real wastewater. The wastewater was collected from an effluent treatment plant that receives domestic wastewater and industrial effluents from chemical, bulk drugs and allied industries, for treatment. In this study the wastewater sample was analysed for total dissolved solids (TDS) and total organic carbon (TOC), and then treated biologically in a respirometer using aerobic microorganisms. After the oxygen uptake curve plateaued, indicating a cessation of biological process, the sample was analysed for TDS and TOC and put in a lab-scale electrocoagulation setup. Iron and Aluminium electrodes were used in the study and efficiency of the system in removing the recalcitrant / residual carbon and TDS was studied with respect to the reaction time. The results showed that electrocoagulation can be a potential post-biological treatment system for removal of recalcitrant carbon from wastewaters.