Current State of Numerical Simulations and Testing for the Blast and Impact Protection of the Build Civil Engineering Infrastructure

The identification of the critical infrastructure has shown that the build civil engineering infrastructure is almost involved everywhere, even with the IT-infrastructure. Therefore, the passive safety of structures is demanded. Security associations have analysed that most assaults came along with explosion and impact scenarios, which amount in 80% of assaults. Consequently, these are the extraordinary loads the structures have to be planned and designed for. To carry out such an engineering job, the engineer has to be educated in multiple disciplines as physics, material science , continuum mechanics, numerical mechanics, testing, structural engineering and related specific fields as wave propagation etc. In this paper we will concentrate on the subjects of numerical simulation and testing.

Integrating ACAD with GIS for Civil Engineering Applications

GIS is a computerized database management system that provides geographic access (capture, storage, retrieval, analysis and display) to spatial data. Civil Engineering projects involve the management, analysis and integration of large amounts of geographic information to ensure success. This can include a wide range of information such as detailed design drawings originating from CAD solutions, detailed mapping, air photography, geological investigations, population information, traffic flows and environmental models. Although there are some similarities between CAD and GIS there are many differences. The most fundamental difference is that GIS mode is the world as it exists, whereas CAD models artifacts yet to be produced. As a result the data manipulated by a GIS is an order of magnitude larger and more complex than CAD systems have to deal with, and the nature of the data, its sources and its uses are quite different. In this paper, the selected area was Nahrain University. Many data were saved on the site map as a transparence layers built by using AutoCAD (2006). Then a digital library was built for the selected area and many data were saved on the site map as a themes built by using ArcView software.

Boulder-induced form roughness and skin shear stresses in a gravel-bed stream

Boulder spacing in mountain rivers and near-wake flow zones within the boulder array is very useful for fish habitat and growth of aquatic organisms.The present study aims to investigate how the boulder array and spacing influence the near-bed flow structures in a gravel-bed stream.Boulders are staggered over a gravel-bed stream with three different inter-boulder spacing namely(a)large(b)medium and(c)small spacing.An acoustic Doppler velocimeter was used for flow measurements in a rectangular channel and the results were compared with those acquired from numerical simulation.The time-averaged velocity profiles at the near-wake flow zones of boulders experience maximum flow retardation which is an outcome of the boulder-induced form roughness.The ratio of velocity differences associated to form and skin roughness and its positive magnitude reveals the dominance of form roughness closest to the boulders.Form roughness computed is 1.75 to 2 times higher than the skin roughness at the near-wake flow region.In particular,the collective immobile boulders placed at different inter-boulder spacings developed high and low bed shear stresses closest to the boulders.The low bed shear stresses characterised by a secondary peak developed at the trough location of the boulders is attributed to the skin shear stress.Further,the spatial averaging of time-averaged flow quantities gives additional impetus to present an improved illustration of fluid shear stresses.The formation of form-induced shear stress is estimated to be 17%to 23%of doubleaveraged Reynolds shear stress and partially compensates for the damping of time-averaged Reynolds shear stress in the interfacial sub-layer.The quadrant analysis of spatial velocity fluctuations depicts that the form-induced shear stresses are dominant in the interfacial sub-layer and have no significance above the gravel-bed surface.

Tensile Strain Capacity Prediction of Engineered Cementitious Composites (ECC) Using Soft Computing Techniques

Plain concrete is strong in compression but brittle in tension,having a low tensile strain capacity that can significantly degrade the long-term performance of concrete structures,even when steel reinforcing is present.In order to address these challenges,short polymer fibers are randomly dispersed in a cement-based matrix to forma highly ductile engineered cementitious composite(ECC).Thismaterial exhibits high ductility under tensile forces,with its tensile strain being several hundred times greater than conventional concrete.Since concrete is inherently weak in tension,the tensile strain capacity(TSC)has become one of the most extensively researched properties.As a result,developing a model to predict the TSC of the ECC and to optimize the mixture proportions becomes challenging.Meanwhile,the effort required for laboratory trial batches to determine the TSC is reduced.To achieve the research objectives,five distinct models,artificial neural network(ANN),nonlinear model(NLR),linear relationship model(LR),multi-logistic model(MLR),and M5P-tree model(M5P),are investigated and employed to predict the TSCof ECCmixtures containing fly ash.Data from115 mixtures are gathered and analyzed to develop a new model.The input variables include mixture proportions,fiber length and diameter,and the time required for curing the various mixtures.The model’s effectiveness is evaluated and verified based on statistical parameters such as R2,mean absolute error(MAE),scatter index(SI),root mean squared error(RMSE),and objective function(OBJ)value.Consequently,the ANN model outperforms the others in predicting the TSC of the ECC,with RMSE,MAE,OBJ,SI,and R2 values of 0.42%,0.3%,0.33%,0.135%,and 0.98,respectively.

Artificial Intelligence Prediction of One-Part Geopolymer Compressive Strength for Sustainable Concrete

Alkali-activated materials/geopolymer(AAMs),due to their low carbon emission content,have been the focus of recent studies on ecological concrete.In terms of performance,fly ash and slag are preferredmaterials for precursors for developing a one-part geopolymer.However,determining the optimum content of the input parameters to obtain adequate performance is quite challenging and scarcely reported.Therefore,in this study,machine learning methods such as artificial neural networks(ANN)and gene expression programming(GEP)models were developed usingMATLAB and GeneXprotools,respectively,for the prediction of compressive strength under variable input materials and content for fly ash and slag-based one-part geopolymer.The database for this study contains 171 points extracted from literature with input parameters:fly ash concentration,slag content,calcium hydroxide content,sodium oxide dose,water binder ratio,and curing temperature.The performance of the two models was evaluated under various statistical indices,namely correlation coefficient(R),mean absolute error(MAE),and rootmean square error(RMSE).In terms of the strength prediction efficacy of a one-part geopolymer,ANN outperformed GEP.Sensitivity and parametric analysis were also performed to identify the significant contributor to strength.According to a sensitivity analysis,the activator and slag contents had the most effects on the compressive strength at 28 days.The water binder ratio was shown to be directly connected to activator percentage,slag percentage,and calcium hydroxide percentage and inversely related to compressive strength at 28 days and curing temperature.

Effects of the Water-Cement Ratio and the Molding Temperature on the Hydration Heat of Cement

The effects of the water-cement ratio and the molding temperature on the hydration heat of cement were investigated with semi-adiabatic calorimetry.The specimens were prepared with water-cement ratios of 0.31,0.38,and 0.45,and the molding temperature was specified at 10 and 20℃.The experimental results show that,as the water-binder ratio increases,the value of the second temperature peak on the temperature curve of the cement paste decreases,and the age at which the peak appears is delayed.The higher the water-cement ratio,the higher the hydration heat release in the early period of cement hydration,but this trend reverses in the late period.There are intersection points of the total hydration heat curve of the cement pastes under the influence of the water-cement ratio,and this law can be observed at both molding temperatures.With the increase in the molding temperature,the age of the second temperature peak on the temperature curve of the cement paste will advance,but the temperature peak will decrease.The higher the molding temperature,the earlier the acceleration period of the cement hydration began,and the larger the hydration heat of the cement in the early stage,but the smaller the total heat in the late period.A subsection function calculation model of the hydration heat,which was based on the existing models,was proposed in order to predict the heat of the hydration of the concrete.

Nonlinear vibration of Timoshenko FG porous sandwich beams subjected to a harmonic axial load

In this study,the instability and bifurcation diagrams of a functionally graded(FG)porous sandwich beam on an elastic,viscous foundation which is influenced by an axial load,are investigated with an analytical attitude.To do so,the Timoshenko beam theory is utilized to take the shear deformations into account,and the nonlinear Von-Karman approach is adopted to acquire the equations of motion.Then,to turn the partial differential equations(PDEs)into ordinary differential equations(ODEs)in the case of equations of motion,the method of Galerkin is employed,followed by the multiple time scale method to solve the resulting equations.The impact of parameters affecting the response of the beam,including the porosity distribution,porosity coefficient,temperature increments,slenderness,thickness,and damping ratios,are explicitly discussed.It is found that the parameters mentioned above affect the bifurcation points and instability of the sandwich porous beams,some of which,including the effect of temperature and porosity distribution,are less noticeable.

Enhancing the Decomposition of Paper Cups Using Galleria Mellonella and Eisenia Fetida

The composition of paper cups creates a challenge for the recycling industry,as the paperboard–plastic film composite is hard to separate.Therefore,paper cups are sent to landfills or waste incinerators.This study explores the combined use of red worms(Eisenia fetida)and Greater wax moth(Galleria mellonella)in the biodegradation of paper cups.The study investigates the conditions and combinations that promote using Eisenia fetida and Galleria mellonella for degrading paper cups.The study considered the influence of environmental temperature,the presence of food waste,varying the number of Eisenia fetida worms,and the presence of a Galleria mellonella growth-slowing agent on the degradation process.To achieve the study objectives,the study followed a quantitative approach.The study monitored the degradation of paper cup cuts that were placed in jars containing different combinations of Eisenia fetida worms,Galleria mellonella larvae,food waste,bedding material,and Galleria mellonella growth-slowing agents.The study found that the best operating temperature is 30oC.The study found that using food waste improves the performance of Eisenia fetida worms and Galleria mellonella larvae significantly.The study found that adding a Galleria mellonella growth-slowing agent slightly enhances the degradation of the paper cup.Finally,a numerical model was obtained to simulate the paper cup degradation efficiency.

Correction to:Error Calculation of Large-Amplitude Internal Solitary Waves Within the Pycnocline Introduced by the Strong Stratification Approximation

In the original publication the third author name is published incorrectly as“Hayatdavoodi Masoud”.The correct author name should be read as“Masoud Hayatdavoodi”.The correct author name is available in this correction.

Nonlinear Study on the Mechanical Performance of Built-Up Cold-Formed Steel Concrete-Filled Columns under Compression

Given their numerous functional and architectural benefits,such as improved bearing capacity and increased resistance to elastic instability modes,cold-formed steel(CFS)built-up sections have become increasingly developed and used in recent years,particularly in the construction industry.This paper presents an analytical and numerical study of assembled CFS two single channel-shaped columns with different slenderness and configurations(backto-back,face-to-face,and box).These columns were joined by double-row rivets for the back-to-back and box configurations,whereas they were welded together for the face-to-face design.The built-up columns were filled with ordinary concrete of good strength.Finite element models were applied,using ABAQUS software,to assess mechanical performance and study the influence of assembly techniques on the behavior of cold-formed columns under axial compression.Analytical approaches based on Eurocode 3 and Eurocode 4 recommendations for un-filled and concrete-filled columns respectively were followed for the numerical analysis,and concrete confinement effects were also considered per American Concrete Institute(ACI)standards for face-to-face and box configurations.The obtained results indicated a good correlation between the numerical results and the proposed analytical methodology which did not exceed 8%.The failure modes showed that the columns failed due to instabilities such as local and global buckling.

Impact of COVID-19 on Safety Performance for Motorcycles: Pre-and during-Pandemic Conditions

Florida has the highest number of motorcycle fatalities in the United States and contains the second largest population of registered motorcycles. The COVID-19 pandemic influenced the roads, traffic, and driving behavior in the continental United States. Motorcycle crashes decreased during the COVID-19 years (2020 and 2021) while the fatality rates increased. The purpose of this study is to 1) investigate motorcycle crashes before and during the Pandemic period to understand the impacts on motorcycle safety and contributing factors to the crash severity levels;2) develop the crash predictive model for different degrees of severity in motorcycle crashes in Florida. Florida statewide crash data were collected. T tests have been conducted to compare the contributing factors between two periods. The injury severities are significantly different among all five levels between those during normal period and the Pandemic period. A crash predictive model has been developed to determine the facts to injury severity levels for motorcycle crashes. A total of eight variables are found to significantly increase the injury severity levels for motorcycle crashes during the Pandemic period.

Effect of Tillage Practices on Hydro-Physical Properties of Soils in a Rice-Grown Environment in North Central Nigeria

This study details soil’s physical and chemical properties in a rice-grown environment in Minna environs Niger State, Nigeria, under different soil and water conservation practices. Soil samples were collected at 0 - 10 cm, 10 - 20 cm and 20 - 30 cm, respectively, using a soil auger to determine their physical and chemical properties such as moisture content, particle size, bulk density, particle density, porosity and organic matter. The textural classification determined the percentage dominance of the soil types in each study site location. The moisture content of site 1 ranged between 14.3% to 13.7%, site 2 ranged between 13.2% to 10.2%, site 3 ranged between 15.4% to 13.2%, site 4 ranged between 15.6% to 13.6% and site 5 ranged between 16.1% to 10.9%. The clay content of sites 3, 4 and 5 is higher than that of sites 1 and 2, while the silt contents of sites 1, 2 and 3 are higher than that of sites 4 and 5. The mean value of soil organic carbon from each study location was 2.37%, 2.03%, 2.43%, 2.07% and 2.17% for sites 1, 2, 3, 4, and 5, respectively. Therefore, site 1 is susceptible to erosion because of poor infiltration rate and well-ploughed or cultivated land by the tractor (harrowed). The particle sizes analysis indicated that the soil type in Site 1 and Site 2 is mainly sandy loam, while Site 3 and Site 5 are mainly loamy and predominantly clay loam in Site 4.

Development of Accident Prediction Model under Mixed Traffic Conditions:A Case Study

Accident prediction models are developed under mixed traffic conditions.Two models have been developed.The first model is a city based traffic accident prediction model.City population and vehicle ownership are the two parameters used to develop the model.A case study of Surat city in Gujarat is taken up.Total accident occurred in the city are regressed with population and vehicle ownership.Second model is the urban arterial based accident prediction model.Past accident record of ring road of Surat city shows that there are eight different locations on a ten kilometer stretch of ring road where the accidents took place consistently.These locations are picked up as accident spots.As there are many contributing factors and causes to road accidents.A comprehensive study of road safety found that human error was the sole cause in 57%of all accidents and was a contributing factor in over 90%.Keeping this in view a new term driver-pedestrian index is used to develop this model.Regression function of Microsoft excel is used for model development.Both the models are checked with R-statistics and t-statistics further the models are validated by using statistical goodness of fit(chi square test).Hence these models can be used to predict number of accidents in future subjected to the same geometric standards.Keeping this in mind improvement measures can be taken up by the district authorities.

The Early Basilica Church, El-Ashmonein Archaeological Site, Minia, Egypt: Geo-Environmental Analysis and Engineering Characterization of the Building Materials

El-Ashmonein is a significant archaeological site with different buildings from various eras. Between the villages of El-Idara and El-Ashmonein are there mains of Hermopolis, one of the ancient Egyptian metropolis capitals of the fifteenth century of Upper Egypt, called the hare. The buildings in this archaeological site are exposed to many causes of destruction and damage. The remaining structures and granite free standing columns in this area are suffered from plenty of geo-environmental and geotechnical problems. The main objectives of this study are 1) to assess the current state of preservation of this important archaeological site, especially the basilica church with its free standing huge columns, 2) to analyze the different actions which cause the destruction of the archaeological site, in particular the old flash floods and earthquakes, and 3) to identify the geochemical and engineering properties of the construction materials of the granitic columns and other limestone structures of the basilica church by using different kind of sophisticated analytical and diagnostic tools and methods. The multi-criteria analysis allowed the integration of several elements for mapping the vulnerable zones. Results revealed that about 80% of the study area was exposed to high and medium old floods vulnerability because of the vicinity to the Nile River. The structural and non-structural measures recommended in this research will help the decision makers and planners to effectively develop strategies for future site management, intervention retrofitting and rehabilitation of this unique archaeological site.

Dynamic discrete element method and its application in rock mass engineering

Based on conventional discrete element method, the idea and calculating method of dynamic discrete element (DDEM) was proposed, and a relevant program was developed. The application of the method is presented in rock mechanics and engineering, which indicates that the method can be widely used in dynamic response and stability analysis of jointed rockmass under dynamic load. [

The Consequence of Particle Crushing in Engineering Properties of Granular Materials

This paper presents experimental investigation for particles breakage for natural sand. The particle breakage was induced by subjecting the sample to one dimensional compression. Grain size analyses were performed before and after induced breakage. Thereafter, the sand shear strength parameters were assessed using direct shear box tests and the coefficient of permeability was assessed using constant head permeameter. Examining the obtained results revealed that the amount of breakage due to one dimensional compression was of order higher than the amount occurring during direct shear test. Peak shear strength parameters decreased with the particles breakage increasing. Moreover, dilation angle of shear strength pronouncedly decreases with the amount of particles breakage increasing. Crushing has obvious effect on the evaluated coefficient of permeability.

A model test system with a dynamic load device for geotechnical engineering in cold regions

A model test system with a dynamic load device for geotechnical engineering in cold regions is presented. This system consists of a model test tank, a refrigeration device and temperature controller, a dynamic load device, together with sensors and data loggers for detecting stress, deformation, and temperature changes. The system can accommodate soil blocks up to 3 m in length, 2.5 m in width, and 1 m in height. The lowest temperature provided by the refrigeration device is -20 ℃. The maximum load provided by the dynamic load device is 100 kN and the vibration fi＇equency of the dynamic load can range from 0.1 to 10 Hz. A number of waveforms, such as sine waves, rectangular waves, triangle waves, and other user-defined waves can be generated by the dynamic load device controller.

Impact of COVID-19 on the Contracting &Engineering Companies in Gaza Strip

Construction projects are among the riskiest projects, which require the application of the right rules and to abide by the proper safety standards. Thus, this study aims to study the impact of COVID-19 on the construction and engineering companies due to the Corona pandemic in the Gaza Strip, and introducing the means used in dealing with this pandemic and how to avoid, limit and deal with it. And to shed light on the most important obstacles and challenges facing the construction sector in the light of the outbreak of the epidemic. To achieve this, a cross-sectional study based on an online questionnaire was conducted by Google Forms. Then, the data collected was analyzed using the thematic analysis approach. The results show that best procedures to mitigate the impact of this epidemic and to prioritize the safety and health of employees in contracting and engineering companies, to provide a safe work environment and developing plans to confront the spread of injury in the work-environment. The study recommends that government may provide financial support to companies and reduce taxes imposed on them in order to be able to confront this pandemic.

Hydraulic and volume change behaviors of compacted highly expansive soil under cyclic wetting and drying

The wide engineered application of compacted expansive soils necessitates understanding their behavior under field conditions.The results of this study demonstrate how seasonal climatic variation and stress and boundary conditions individually or collectively influence the hydraulic and volume change behavior of compacted highly expansive soils.The cyclic wetting and drying(CWD)process was applied for two boundary conditions,i.e.constant stress(CS)and constant volume(CV),and for a wide range of axial stress states.The adopted CWD process affected the hydraulic and volume change behaviors of expansive soils,with the first cycle of wetting and drying being the most effective.The CWD process under CS conditions resulted in shrinkage accumulation and reduction in saturated hydraulic conductivity(k sat).On the other hand,CWD under CV conditions caused a reduction of swell pressure while has almost no impact on k sat.An elastic response to CWD was achieved after the third cycle for saturated hydraulic conductivity(k sat),the third to fourth cycle for the volume change potential under the CV conditions,and the fourth to fifth cycle for the volume change potential under the CS conditions.Finally,both swell pressure(s s)and saturated hydraulic conductivity(k sat)are not fundamental parameters of the expansive soil but rather depend on stress,boundary and wetting conditions.

引入强分层近似对含密度跃层情况下的大幅内孤立波计算误差研究

At present,studies on large-amplitude internal solitary waves mostly adopt strong stratification models,such as the twoand three-layer Miyata–Choi–Camassa(MCC)internal wave models,which omit the pycnocline or treat it as another fluid layer with a constant density.Because the pycnocline exists in real oceans and cannot be omitted sometimes,the computational error of a large-amplitude internal solitary wave within the pycnocline introduced by the strong stratification approximation is unclear.In this study,the two-and three-layer MCC internal wave models are used to calculate the wave profile and wave speed of large-amplitude internal solitary waves.By comparing these results with the results provided by the Dubreil–Jacotin–Long(DJL)equation,which accurately describes large-amplitude internal solitary waves in a continuous density stratification,the computational errors of large-amplitude internal solitary waves at different pycnocline depths introduced by the strong stratification approximation are assessed.Although the pycnocline thicknesses are relatively large(accounting for 8%–10%of the total water depth),the error is much smaller under the three-layer approximation than under the two-layer approximation.