జర్నల్ ఆఫ్ సివిల్ అండ్ ఎన్విరాన్‌మెంటల్ ఇంజినీరింగ్

Buckling and post-buckling are among the most important failure factors in thin walled structures. The loadcarrying behavior of cylindrical thin-walled shell structures under external pressure load is strongly dependent upon the nature and magnitude of the initial imperfections. These imperfections are invariably caused by an assortment of manufacturing processes like installing or welding. One of the most important imperfections caused by welding that has been reported to have an essential detrimental effect on the buckling resistance of these shells under external pressure load is longitudinal imperfections. Buckling and post buckling capacity of the shells depend on the H/R and t/ R ratios (H the height, R the radius and t the thickness of a cylindrical shell). The present work discusses the finiteelement models labeled as SS (Shallow Slim), DS (Deep Slim), ST (Shallow Thick) and DT (Deep Thick). The samples of first group are modified to include a line longitudinal imperfection, amplitudes of 0.5t, 1t, 2t, 3t, 4t and 8t in depth (t is the thickness of cylindrical shell). The results presented are in agreement with international codes and theories concerning buckling.

Our sustainable future is currently not clear as we continue to unsustainably use our natural resources for modern civilization, urbanization and technological advancement. The need for change in attitude towards the environment and a diligent search for using the environment sustainably are therefore, on the lips of everyone. Universities however, are especially placed in the diligent search for sustaining the environment given their combined mission of research, civic education and engagement. The purpose of this article therefore, was to find out the extent to which Ghanaian Technical University (GTUs) are fulfilling this role. The study design was descriptive. Data was gathered from four GTUs using semi-structured questionnaires. The quantitative component, measured on a three-point Likert scale was analyzed using descriptive statistics (percentages) with the help of the Statistical Package for the Social Sciences (SPSS). The qualitative component was analyzed using thematic analysis. One of the key findings of the study was that, although energy and water sustainability were generally part of the competencies required of student, sustainable projects, pollution management, recycling and the use of sustainable building materials were rarely considered. A key recommendation was that energy and water conservation and development issues should be made part of the range of courses offered by technical universities.

There can be many causes of deterioration in concrete structures. Concrete repaired is a specialist activity requiring fully trained and competent consultants and companies at all stages of the process. Often simple “patch and paint” strategies have been employed as short term cosmetic repairs which have failed to address the root cause of the problem and have, as a result, often failed to meet structure owners expectations. Nanotechnology provides insight into the use of nanomaterials in the following areas: Protection against ingress– moisture control– concrete restoratio – structural strengthening– physical resistance to chemicals– preserving or restoring passivity- increasing resistivity– cathodic control– cathodic protection control of anodic areas. This paper is state of the art for using nanotechnology in repair and protection of concrete structures. It is hoped that this paper will help researchers to be aware of the most recent progress in this important field.

In Japan, nearly a half or even more of the existing bridges with a span exceeding 15 meters were predicted to be over 50 years old in next 10 years. Appropriate repair, strengthening, or replacement work should be performed on aged steel bridge structures to ensure their performance in service condition. A novel strengthening method using rubber-latex mortar, glass fiber reinforced polymer plates, lightweight rapid hardening concrete, and reinforcement bars is proposed for strengthening short-span steel railway bridge superstructures and for improving the seismic performance of aged column structures. To confirm the effectiveness of the strengthening method, loading tests were performed on test specimens for short-span steel railway bridges, longitudinal-lateral beam connections as well as steel columns. Numerical models were also built to simulate the structural behavior of both original and strengthened steel structures. According to the obtained results, the present renovation method can significantly enhance both rigidity and load carrying capacity of short-span steel bridge superstructure, connections, and column structures, resulting in the extension of the residual fatigue service life of bridge tarp structures and improvement of seismic performance of column structures.

Simulations and field tests have shown that the connected vehicle technologies would not only enhance the mobility and safety of traffic operation, but also possibly reduce fuel consumption and exhaust emissions. So far, there is no consistent evaluation procedure on the perfomances of these in vehicle messages to drivers in work zone area. The objective of this research is to test, compare and develop a warning system to prevent occurring of work zone crashes and reduce vehicle emission. The main purpose of this study is to test and evaluate the different set of warning messages in the advance warning area of a work zone and develop an evaluation system for the warning system from the perspective of speed, acceleration rate, brake positions, lane changing positions, emission and work load. The work load of the three types of warning system is evaluated based on the NASA-TASK Load Index. The application of the mixed audio and image messages was able to reduce the overall vehicle emissions (CO₂, CO, HC, and NOx). With the help of the both audio and image messages, drivers tend to recognize the road situation earlier than in the conventional situation and this will have a positively influence on driving safety. Especially, the mixed messages scenario outweights the other two scenarios in speed, acceleration rate, braking positions, emission, and work load.

Secondary flows are present in open channel due to the complex three-dimensional flow structures as a result of the existing natural features (e.g. different boundaries) affecting the flow. This paper experimentally examined the structure of secondary flow in open channel with a patchy gravel and vegetated beds using two different experimental conditions. A high resolution three-dimensional instantaneous velocity measurement over the gravel and vegetated bed were made using the acoustic Doppler velocimeter (ADV) and the secondary flow quantities determined. The results reveal that the magnitude of secondary flow over the gravel bed in experiment one is relatively large with occurrence of down-flow, and up-flow over the flexible vegetated bed. The lateral interaction and momentum transfer between the two-bed roughness (gravel and vegetated beds) is achieved by the secondary flow, at the lower region of the flow, the transverse motion is directed from the gravel bed towards the grass bed, and at the upper region, and the flow is transported laterally in the opposite direction.

Existing method of forecasting inflows at Tarbela have some limitations, also system needs an adequate operating policy model to deal with highly volatile inflow of summer months of June, July, August and September. In this paper, historical data of inflows from 1986 to 2014 have been used to forecast upcoming inflows at dam. Bayesian predictive distribution is used to predict future inflows. These forecasted inflows were further incorporated into operating policy model to determine the optimal release during the prescribed months. Weather volatility is a major factor causing unstable inflows. High temperature during summer period cause high inflows at dam. Considering weather volatility, this policy model is proposed for the flood season (15th June to 30th September), in which inflows and outflows are higher than rest of the year. This model maximizes the expected profit from hydro power production, minimizes the expected loss from flood damage and updates the proper estimate of current stage of reservoir storage.

Several R.C. (reinforced concrete) beams research have been surveyed in the shear area using fiber-reinforced polymer (FRP) composites and ended in collapse in the shear due to the separation of the FRP. The NSM method utilizing fiber fortified polymer (FRP) bars is currently an entrenched method for the reinforced concrete strengthening structures. The main proposal of this search is to look into experimentally for strengthening shear behavior with RC NSM carbon fiber reinforced polymer (CFRP) bars and exhibit the numerical outcomes for strengthened beams in shear with various FRP types; carbon fiber bar (CFRP), aramid fiber bar (AFRP), and glass fiber bar (GFRP) in shear. Three-dimensional beam models using finite element method are formed with software ANSYS-2013 to study the behavior of FRP in strengthening. Finally, a simply proposed equation is produced to estimate the shear strengthening capacity. The proposed equation affirms the exactness and viability of the experimental numerical result.

Air Pollution may be defined as any atmospheric condition in which certain substances are present in such concentrations that they can produce undesirable effects on man and his environment. The Air Quality Index (AQI) is a reporting system and an important tool of risk communication. It informs the public about the level of ambient air quality, and the potential health risk it would impose. AQI converts complex air quality data of various pollutants into a single number (index value), nomenclature and colour. AQI is represented as numeric value varies from 0 to 500. If score is 0, it is the best air quality and if score is 500, it is the worst air quality. There are six AQI categories, namely Good, Satisfactory, Moderate, Poor, Very Poor, and Severe. Each of these categories is decided based on ambient concentration values of air pollutants and their likely health impacts. In Tamil Nadu, under National Ambient Air Quality Monitoring Programme, Ambient Air Quality (AAQ) is being monitored by Central Pollution Control Board in association with Tamil Nadu Pollution Control Board in 28 locations covering cities, major towns and major industrial areas viz. Chennai, Salem, Coimbatore, Madurai, Trichy, Cuddalore, Mettur, and Thoothukudi. The AAQ data from January 2015 to December 2015 for the above cities and towns is collected and AQI is calculated for four months covering four seasons (i.e.,) January (winter), May (summer), July (monsoon), November (post monsoon). Almost all the stations’ AQI fall under good and satisfactory category except Trichy where the majority of the days the AQI fall under moderate category. From the AQI of all the stations, it is observed that responsible pollutant is PM10. The other parameter (i.e.,) SO2 and NO2 fall under good category for all stations for all days. The higher value of PM10 is mainly due to vehicular pollution.

The effect and optimization of using self-compacting rubberized concrete was investigated by using Taguchi method. Design of experiment was performed via orthogonal array to accommodate four factors with four levels. These factors were the percentage of fine rubber, coarse rubber, fly ash and viscocrete in the concrete mix. The signal-to-noise (S/N) ratio and the analysis of variance (ANOVA) were employed to study the performance characteristics of self-compacting rubberized concrete (SCRC). Rubberized concrete can be improved using the concrete proportioned as self-compacting concrete. The results indicate that there was a reduction in the strength with increasing rubber content but there was an increase in impact resistance. However, the replacement of 10% of coarse aggregate with coarse rubber gave more strength than that of zero rubber mix by 124% at 90 days. Replacement of 20% of both fine and coarse aggregates with fine and coarse rubber respectively, increased impact resistance by 453% compared to the corresponding SCRC control mix.

The electromagnetic radiation (EMR) emitted by mobile phone devices (n=52) has been monitored as a function of the operation mode and the distance from the device. Measurements (electric field, V/m) were administered in the metropolitan area of Athens, Greece and involved a total of 52 mobile phone devices operating in the 1.5 GHZ-2.1 GHz frequency range. Five distinct operation modes of the device (“long term inactivity”, “ringing/call effort”, “usage”, “right after the end of the call”, “short term inactivity”) and a total of two distances from the device (0 m and 1 m) were employed. Depending on the intensity of the individual peaks observed in the experimental spectra at 0 m, the mobile devices were shown to cluster into three subgroups as follows: Subgroup 1 (n1=24, peak intensities>1 V/m), Subgroup 2 (n2=9, peak intensities in the range of 0.1 V/m - 1 V/m), Subgroup 3 (n3=19, peak intensities<0.1 V/m). Statistical analysis via repeated-measures analysis of variance (RM-ANOVA) provided evidence for a statistically significant effect of the operation mode on the emitted EMR by the mobile device. The effect was more prominent at the shortest distance (0 m) and for the devices of one specific subgroup (Subgroup 1). The transition between operation modes which shows the largest effect (increase) in the emitted EMR is the one from “long term inactivity” to “Ringing/Call effort” irrespective of device subgroup. Examination of the effect of the distance on the emitted EMR resulted to the following findings: At the longer distance employed (1 m), the devices belonging to Subgroups 2 and 3 continue to exhibit mean EMR intensity similar to the one at 0 m under all operation modes. On the other hand, upon distance increase, the emitted EMR intensity of the devices belonging to Subgroup 1 displays a statistically significant decrease in all operation modes except the one of ‘long term inactivity”.