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Innovative Infrastructure Solutions
Number of Followers: 0  Hybrid journal (It can contain Open Access articles)ISSN (Print) 2364-4176 - ISSN (Online) 2364-4184 Published by Springer-Verlag  [2469 journals]
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- Effect of recycled concrete aggregate on mechanical, physical and
durability properties of GGBS–fly ash-based geopolymer concrete-
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Abstract: Abstract Low-calcium fly ash (LCFA)- and ground granulated blast furnace slag (GGBS)-based geopolymer concretes are eco-friendly novel concrete to be used as an alternative to traditional OPC concrete. Natural resources are used in the production of cement, while industrial and demolished concrete wastes such as GGBS, LCFA, and recycled concrete aggregate (RCA) are used in the production of geopolymer concrete (GPC) to save natural resources. In this study, the aim is to produce a novel geopolymer concrete with a fairly high strength, up to 85 MPa as compared to the strength achieved so far by other researchers using RCA, GGBS, and LCFA. In addition to this, the emphasis is to utilize the used coarse aggregate obtained from demolished waste. The other objective is to produce the concrete usable in arid regions where water is scarce. These objectives have been accomplished in two steps have followed. In the first step, the preparation of solid and liquid binders was accomplished. The actual solid binders were decided based on trial solid binders consisted of LCFA and GGBS in the ratios of 3:2, 2:3, and 1:4. The liquid binder taken was a solution of silicate and hydroxide of sodium. In the second step, used coarse aggregate after removing the old mortar coating from the surface, was used as a substitute for 25%, 50%, 75%, and 100% of natural coarse aggregate in the GGBS–LCFA-based GPC. The impact of the RCA on the workability, physical and mechanical properties, and durability properties of the produced GPC was determined. The mechanical properties of all the mixes were satisfactory. However, the GPC with sample mix F40G60R0 has proved to be the most satisfactory of all the properties. Sample mix F40G60R50 with 50% RCA and 60% GGBS addition showed the highest compressive strength of 84.31 MPa among all the mixes except sample mix F20G80R0. The presence of RCA in the matrix increased the number of nucleation sites available in the interfacial transition zone (ITZ), resulting in a denser matrix structure. The major difficulty faced was the complete removal of the old mortar coating from the used coarse aggregate to produce RCA. The results revealed that GPC may include a high percentage (up to 100%) of RCA with 60% of GGBS to give sufficient strength for practical applications.
PubDate: 2022-05-18
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- Enhancing the sustainability of high strength concrete in terms of
embodied energy and carbon emission by incorporating sewage sludge and fly
ash-
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Abstract: This paper discusses the properties of dried sewage sludge (SS) and its influence on the microstructure development of HVFA concrete when used as a partial replacement of binder material. A detailed characterization of dried sludge samples collected from a sewage treatment plant is carried out using XRF, XRD, TGA, and FTIR techniques. HVFA concrete mix is designed for 50 MPa with 50% fly ash of the total binder content. Sludge is ground to a particle size of 150 µ and 75 µ and replaced at levels of 5%, 10%, and 15% of the total binder content. The strength activity index of the dried sludge sample is acceptable as per standards. Taking concrete mixes with HVFA as a reference, the fresh properties of binder paste and concrete with sewage sludge have been studied. Mechanical properties that define the applicability to various infrastructure projects are reported for all the studied mixes. EI, CI, COST per unit compressive strength for all mixes are also determined to comment on the environmental impact of the use of SS in concrete. The compressive strength of concrete specimens decreases with the increase in replacement level of SS. However, in comparison with OPC concrete, 75 µm SS at 5% replacement level concrete mechanical strength is within the acceptable limit for M50 concrete mix. The addition of SS as a binder to the concrete has a lower environmental impact, embodied energy, CO2 emission, and cost per unit strength. But more than 10% replacement level resulted in reducing CS, FS, and STS by 11.17%, 6.23%, and 6.99%. Graphical abstract
PubDate: 2022-05-18
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- Thermophysical characteristics of eco-friendly mortars containing recycled
PET as partial sand replacement in dry and wet conditions-
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Abstract: Plastic has become one of the most widely manufactured materials in the world and a key part of daily life. However, a large amount of plastic waste must be recycled to protect the environment. One of the ways of recycling is to use this waste as a substitute for raw material. This study aims to provide a thermophysical characterization of an eco-friendly mortar. This material is characterized by the partial replacement of sand with recycled PET. The sand was partially substituted (5, 10, 15, and 20%) by recycled PET with a water/cement ratio of 0.5. Thermophysical properties, which are thermal conductivity, volumetric specific heat, and thermal diffusivity, were measured experimentally in the dry and wet (water-saturated) state. These properties were determined as a function of the percentage of recycled PET using a Hot Disk analyzer. The workability, density, ultrasonic pulse velocity, and compressive strength of the samples were also evaluated. Experimental results revealed that with the addition of recycled PET, workability increased to a maximum value of 370 mm. The density of the mortar decreased by approximately 6.76% in the dry state and 4.28% in the wet state for a substitution rate of 20%. Thermophysical parameters also decreased linearly when 20% PET was added to the cement mortar: 46.81% for thermal conductivity with a minimum value of 0.693 W/mK, 26.80% for specific volumetric heat, and 27.34% for thermal diffusivity. A very good correlation (R2 = 0.9847) was shown between compressive strength and ultrasonic pulse velocity, both decreasing with increasing percentages of recycled PET. The use of recycled PET as a partial replacement of sand affects the thermophysical properties of the cement mortar due to its porosity compared to the control mortar, thus highlighting the potential use of these mortars as energy-efficient and environmentally friendly construction materials. In addition, this is an ecological and sustainable practice as it conserves natural resources. Graphical abstract
PubDate: 2022-05-18
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- A critical assessment of existing prediction models on the shear capacity
of recycled aggregate concrete beams-
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Abstract: Abstract The open literature evidently indicates that the shear capacity of reinforced concrete beams is adversely affected by the replacement of natural concrete aggregate by recycled concrete aggregate (RCA), and several equations for estimating the shear capacity were proposed. This paper provides a critical assessment of the existing prediction equations for estimating the shear capacity of RAC beams. The assessment is conducted utilizing Bayesian parameter estimation for comparison between the seventeen existing prediction models of the shear capacity of RAC beams. This robust assessment technique against false conclusions yields more informative and richer inferences than a mere comparison with the experimental shear capacities by providing a complete distribution of the mean and standard deviation of the quality of the prediction (i.e., test-to-predict shear values). A clear ranking of the existing prediction equations is performed based on the degree of conservatism and uniformity of the design provided by each of the shear strength prediction equations. This paper also directly addresses the significant parameters that influence the shear strength of RAC beams based on the grey correlation analysis (GCA) and check whether the existing prediction equations include these important parameters.
PubDate: 2022-05-18
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- Use of fly ash in the production of geopolymers: a literature review
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Abstract: Abstract Currently, the high pollution derived from the production of Portland cement is a major problem, therefore the development of alternative cements obtained by processes with lower gas emissions and low energy consumption is a new line of research of worldwide interest. It is proved that geopolymers can replace Portland cement in some application in the construction industry; however there are lack of critical reviews about finding of it during the last years. The main objective is to perform a critical analysis of the existing literature on material sources, physical and chemical characteristics of fly ash, combination, geopolymer manufacture and its properties; to complete that 91 indexed manuscripts from different data sources were analyzed. This review reveals that the optimal burning of the materials improves their characteristics and generates a higher compressive strength of the geopolymers, and it is also concluded that the most practical way to mix the inputs is by combining at the same time the alkaline solutions and the fly ashes. In the case of mortars and concretes, similar and higher values in compressive strength have been reported, but lower values in flexural strength with respect to conventional Portland cement. While alternative activators such as CCA, it is proven that their inclusion does not affect the strength of the mixture, finally it is found that fly ashes can contain heavy metals, and these are encapsulated and immobilized in the geopolymerization process, complying with environmental standards.
PubDate: 2022-05-12
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- Thermal, chemical and rheological properties of asphalt binders extracted
from field cores-
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Abstract: Abstract The intermediate-temperature performance of extracted asphalt binders (EABs) is altered when recycled asphalt shingles (RAS) and/or reclaimed asphalt pavement (RAP) are included in asphalt mixes. This happened as a result of the RAP’s aged asphalt binder and the RAS’s oxidized air-blown asphalt. Thus, the rheological properties of EABs from field cores were examined at intermediate temperatures. The fatigue life and the Superpave fatigue cracking parameter were among the rheological properties. Thermogravimetric analysis and Fourier transform infrared were used to analyze EABs’ thermal and chemical characteristics, respectively. The relationships between EABs’ fatigue cracking resistance, thermal, and chemical characteristics were scrutinized. Ages of mixes, percentages of RAP and/or RAS, and intermediate performance grade (PG) temperatures of virgin asphalt binders (VABs) controlled the resistance of EABs to fatigue cracking. Considering VABs with the same intermediate PG temperatures, EABs from older mixes with higher RAS percentages had higher resistance to fatigue cracking than those from younger mixes with lower RAP percentages. When RAP percentages in asphalt mixes were increased, EABs’ resistance to fatigue cracking deteriorated. Thermal and chemical analyses along with rheological characteristics are suggested as indicators of EABs’ intermediate-temperature performance.
PubDate: 2022-05-11
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- Durability performance of expansive soil ameliorated with binary blend of
additives for infrastructure delivery-
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Abstract: Abstract In the course of reducing environmental nuisance, the usage of waste residue is gaining momentum in soil re-engineering protocols. This is because of the pozzolanic tendencies attributed to these waste derivatives during the treatment of weak engineering soils. This necessitated the present study to explore the utilization of binary additive materials known as cement kiln dust (CKD) and metakaolin (MTK) in ameliorating the durability performance of black cotton soil (BCS). Black expansive clayey soils are complex materials, especially during seasonal changes, thereby becoming a road material cancer to the civil engineering profession. Using Scheffe’s technique, a total of twenty (20) different mix combinations of black cotton soil, water, cement kiln dust, and metakaolin were taken into consideration for the experimental protocols and modelling of the durability performance via loss of strength on immersion technique. The deployment of Scheffe’s design of experiment approach occasioned a peak durability performance of 87% at a mixture ratio of 1.0:0.30:0.35:0.50 with a corresponding mass conversion (%) values of 1.93:0.579:0.676:0.965 for black cotton soil, water, cement kiln dust, and metakaolin, respectively. Interestingly, the level of adequacy of the model was verified by means of statistical packages such as t-test and ANOVA; the upshot of the test shows better a correlation between the model and control results. Also, the program was found useful in predicting the tested soil property. In a step further, non-destructive test termed scanning electron microscopy (SEM) was explored to understudy the ups and downs at the micro level of both the virgin and optimally treated soil materials. Judging from the outcome of the SEM experiments, the unaltered soil was at variance with the ameliorated soil.
PubDate: 2022-05-10
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- The effect of using low reactive metakaolin on performances of geopolymer
binder-
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Abstract: Abstract Commercial MK is widely used in the synthesis of geopolymer binders because of its high kaolinite content and reactivity. However, the possibility of producing geopolymers with low reactive MK is not sufficiently experienced and deserves to be verified. The present study deals with the potential use of a low reactive traditionally elaborated metakaolin (MK) and a local ground-granulated blast-furnace slag (GGBFS) as precursors for geopolymer synthesis. The precursor composition (MK/GGBFS: 100/0, 80/20 and 50/50 wt%) and the activator properties (SiO2/Na2O molar ratio (MR): 2; 1.5 and density: 1.4; 1.3 g/cm3) are the variables used to formulate twelve geopolymer mixes. Furthermore, various curing conditions (temperatures of 60, 80 and 100 °C and durations of 6, 24 and 48 h) were chosen for the hardening of geopolymer pastes. An optimization approach has been used in the attempt to deduce the optimal formulation and curing conditions allowing the synthesis of geopolymer with good performances. Tests of setting times and compressive strength were performed on geopolymer pastes in order to assess the effects of different MK/GGBFS contents, activator properties and curing conditions on the performances of geopolymer pastes. The hardened samples were analyzed by scanning electron microscopy (SEM). It has been demonstrated that the used MK, despite its low reactivity, may lead to geopolymer of good performances. The best formulation was 80/20 of MK/GGBFS activated with a sodium silicate solution, the MR and the density of which were 1.5 was 1.4 g/cm3, respectively. On the other hand, the suitable curing temperature was often 60 °C, especially for curing duration of 48 h.
PubDate: 2022-05-08
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- Artificial neural network-based roughness prediction models for gravel
roads considering land use-
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Abstract: Abstract The Wyoming Technology Transfer Center (WYT2/LTAP) is in the process of developing a holistic and integrated Gravel Road Management System (GRMS). As a part of this effort, gravel roads condition prediction models have been developed. The developed models aim to predict the roughness of gravel roads in terms of International Roughness Index (IRI) considering the land use and the traffic volume levels. Approximately 700 miles of gravel roads in Laramie County, Wyoming were tested and evaluated. The land use of each road was classified into three groups: residential, agricultural, and industrial. While the traffic volume, for the purpose of this study, was categorized into three levels: low, moderate, and high. Both land use and traffic volume levels were found to have significant effect on the IRI deterioration over time. Initially, multiple linear regression was used to develop IRI prediction models. The developed multiple linear regression models represented the data with accepted coefficient of determination (R2) level. Also, Artificial Neural Network (ANN) was used to develop prediction models for the IRI. ANN process started by using 70% of the data to train the model, then the remaining 30% were used for validation and testing. One ANN prediction model was developed for each land use. ANN prediction models showed significantly more ability to represent the data than multiple linear regression. The developed prediction models can be an essential part for developing a holistic GRMS and improving better understanding for gravel roads deterioration behavior.
PubDate: 2022-05-06
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- Vulnerable member assessment of power transmission towers collapsed during
Vardah cyclone-
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Abstract: Abstract The investigation on power transmission tower failures during the Vardah cyclone has forced the need for assessing the most vulnerable parts of the towers and their failure mechanisms. In India, Vardah cyclone brought a huge devastating effect that includes the failure of more than 500 power transmission lines and the collapse of 54 high tension transmission towers which lead to huge power disruption. In this research, one such similar transmission tower is considered and initially checked for its capacity followed by static linear buckling analysis to evaluate its critical members of failure. The parameters such as critical stress, joint forces, maximum displacement and failure modes are assessed considering the strong wind force of Vardah having a speed of about 155 Km/hr. The linear buckling analysis has been carried out by SAP2000 commercial software, which illuminated the critical stress and the panel failures for both leg and the diagonal members. The study focuses on the spotting of the most vulnerable member by assessing the parameters like critical stress, maximum panel drift ratio and joint forces by which the integral stability of the tower panel can be identified. The numerical research findings are validated with the actual real-time post failure patterns of the transmission towers. The members with high critical stress, joint force and maximum panel drift are considered to be the most vulnerable members and they act as the failure initiators leading to a progressive collapse condition. These vulnerable members need more attention during the design and implementation phases. Suggestions are highlighted to strengthen these vulnerable members where the emphasis can be given to avoid such similar failure scenarios.
PubDate: 2022-05-06
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- Performance evaluation of post-grouted drilled shafts: a review
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Abstract: Abstract Base grouting in drilled shafts has been used to improve the foundation performance. The main objectives of this technique are to generate a preload in the base soil, induce negative friction on the pile side, and improve the soil surrounding the shaft. In recent years, new experimental and numerical studies were published, which have helped to better understand the soil–post-grouted drilled shaft interaction mechanism. Likewise, new grouting devices were developed, and design methodologies were introduced. This review paper focuses on the analysis of available approaches to investigate the performance of post-grouted drilled shafts (PGDS). The mechanisms of post-grouting of drilled shafts to improve the bearing capacity of pile foundation are discussed, and some properties of the grout typically used in this procedure (such as water–cement ratio, type of grout, etc.) are described. Based on the literature survey, this study presents the devices used to distribute the grout at the tip and side pile, the grouting techniques, and the effect of grout pressure and grout volume on pile behavior. The investigation indicated that the enhancement in pile bearing capacity is affected by the grout quantity, grouting pressure, pile dimensions, soil type, etc. Subsequently, full-scale field tests, small-scale tests, and numerical investigations published to analyze the performance of PGDS are summarized. Finally, the design methodologies available in the technical literature and future developments for this type of foundation are discussed.
PubDate: 2022-05-03
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- A state of review: challenges and techniques of laterite soil
stabilisation using chemical, economical, and eco-friendly materials-
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Abstract: Abstract To date, the instability, as well as the strength of laterite soils in the construction application, has been widely addressed by many scholars. One of the main strategies to improve the laterite soil’s characteristics is to utilise an effective soil stabiliser (i.e., chemical stabilisation). Previous studies have shown that the strength of the laterite soil has been increased considerably through the utilisation of effective soil stabilisers in various applications. Besides tackling the limitations of laterite soils, concerted efforts worldwide have sought to achieve the desired engineering soil properties by using a cost-effective and environmental-friendly approach. To this end, this study aims to thoroughly review the existing soil stabilisers in the literature, which were developed in previous experimental studies. First, an introduction of the laterite composition and the laterite soil’s stabilisation mechanism was provided, followed by a detailed discussion on a variety of soil stabilisers. Various materials were investigated in terms of their effectiveness as efficient soil stabilisers. However, this study primarily focused on economical and eco-friendly materials, including industrial solid waste, agricultural wastes, mineral solid wastes, chemical materials, geo-polymeric binders, and various ashes. The effectiveness of these materials has been assessed using the unconfined compressive strength test and the California bearing ratio test. Finally, several key challenges and future scope of the laterite soil stabilisation using soil stabilisers were carefully addressed.
PubDate: 2022-05-03
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- An experimental study on the rocking behavior of circular and square
footings under slow-cyclic loading-
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Abstract: Abstract Previous studies have emphasized the potential merits of employing the soil–foundation system in dissipating seismic energy and limiting the inertia forces transmitted to the superstructure. This philosophy in design, termed “rocking isolation,” encourages the exhibition of nonlinear behavior in the soil–foundation system rather than structural elements, thereby reducing structural demand. Circular foundations are commonly used to support single-pier slender structures such as wind turbine towers, industrial chimneys, and power towers. The adoption of the rocking isolation concept in the design of such structures' foundation can significantly help their structural integrity as they are highly prone to form plastic hinges in their column base when exposed to intense seismic forces. This study aims to first discuss the main parameters affecting the rocking performance of a typical square foundation and then uses the findings to investigate the shape effect on the rocking behavior of the square and circular foundations. Square and circular foundations with equal areas were systematically tested using a single-degree-of-freedom structure model in various initial static vertical factors of safety ( \(F{S}_{v}\) ) values and subgrade conditions in a series of 1g slow-cyclic experimental tests. The results revealed that in similar \(F{S}_{v}\) values, the lightly loaded foundation rested on loose sand settles more and establishes considerable residual rotation in comparison with the heavily loaded foundation rested on dense sand. The square foundation exhibited superior moment capacity and rotational stiffness considering both \(F{S}_{v}\) parameter and critical contact area ratio ( \(A/{A}_{c}\) ), whereas the circular foundation excelled in terms of the settlement and recentering capability based on \(F{S}_{v}\) parameter.
PubDate: 2022-05-03
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- Developing machine learning model to estimate the shear capacity for RC
beams with stirrups using standard building codes-
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Abstract: Abstract Shear failure in reinforced concrete (RC) beams with a brittle nature is a serious safety concern. Due to the inadequate description of the phenomenology of shear resistance (the shear behavior of RC beams), several of the existing shear design equations for RC beams with stirrups have high uncertainty. Therefore, the predicted models with higher accuracy and lower variability are critical for the shear design of RC beams with stirrups. To predict the ultimate shear strength of RC beams with stirrups, machine learning (ML)-based models are proposed in the present research. The models were created using a database of 201 experimental RC beams with stirrups gathered from earlier investigations for training and testing of the ML method, with 70% of the data being used for model training and the rest for testing. The performance of suggested models was evaluated using statistical comparisons between experimental results and state-of-the-art current shear design models (ACI 318–08, Canadian code, GB 510010–2010, NZS 3101, BNBC 2015). The suggested machine learning-based models are consistent with experimentally observed shear strength and current predictive models, but they are more accurate and impartial. To understand the model very well, sensitivity analysis is determining as input values for a specific variable affect the outcomes of a mathematical model. To compare the results with different machine learning models in training and testing R2, RMSE and MSE are also established. Finally, proposed ML models such as gradient boost regressor and random forest give higher accuracy to evaluate the shear strength of the reinforcement concrete beam using stirrups.
PubDate: 2022-04-27
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- Electroless nickel (EN) coating of mild steel bar as an innovative
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Abstract: Abstract The effective supplementary preventative measures must be implemented during the building stage of base structures due to rebar corrosion. In the current research work more than five experiments are conducted to assess the performance of high yield strength steel bars, both with and without protective coating. Bond strength and adhesion tests are used to evaluate the efficiency of corrosion resistant qualities of 10 μm, 20 μm, and 30 μm coated steel over a period of time. The obtained result shows that the coating is stable. Finally, it is determined that the investigated EN plated rebars, regardless of coating thickness, have the desired corrosion resistance qualities required to meet Indian and ASTM standards. And it is fit for construction in coastal and other areas.
PubDate: 2022-04-25
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- Influence of spatial variability of soil elastic modulus on elastic
settlement of rectangular footing under fuzzy uncertainty-
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Abstract: Abstract It is quite unlike having a uniform soil stratum in-situ because of various methods of formation of the soil over depth. Different depositional processes make the soil nonhomogeneous and more commonly a material (soil) with inherent variability, which necessitates considering inherent soil variability in line with the reliability assessment of geotechnical structures. Therefore, in this paper, an attempt is made to assess the reliability of elastic settlement of rectangular footing resting on both homogeneous and layered cohesionless soil strata using the fuzzy set theory coupled with the finite element method. The elastic modulus of the soil is assumed as a fuzzy variable following the triangular membership function. Moreover, spatial variability of soil elastic modulus is considered for both isotropic and anisotropic scales of fluctuation. Analyses are carried out for both homogeneous and layered (stronger layer underlain by a weaker layer) soil medium. A parameter indicating the required limiting settlement to achieve zero probability of failure is proposed, and a number of design charts are presented for different aspect ratios of footing and scales of fluctuation of soil elastic modulus. Results reveal that the increment in the failure probability is observed as the aspect ratio of footing increases. It is also noticed that the anisotropic scale of fluctuation always predicts conservative results in terms of foundation safety.
PubDate: 2022-04-22
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- Razzaza Lake, a natural water body: its hydraulic characteristics and
water quality-
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Abstract: Abstract Razzaza Lake is a depression that has been used for water storage created by the water management system in Iraq. This research examines the hydraulics characteristics and water quality of Razzaza Lake for the period 2006–2020. The hydraulic characteristics of Razzaza Lake are concerned with the quantity of Razzaza Lake storage and water level fluctuations, whilst the quality of water is concerned with the total dissolved salts (TDS), hardness of water, chlorides (Cl−) and sulfates (SO4−2). Results provide invaluable information on the water level. The monthly discharge inflow to the lake through the study period is found to be 15 m3/sec, which is less than the minimum designed inflow discharge of 100 m3/sec of the lake. This phenomenon reduced the water level from the annual average of 23.05 to 20.81 m.a.s.l. during the studied period and caused a decrease in the average annual capacity storage of the lake from 2.418 × 109 to 1.042 × 109 m3 and shrinkage in the top surface area from 742.55 × 106 to 483.66 × 106 m2. Results of water quality showed that the annual TDS is 11435 ppm; hardness of water is 4617.08 ppm; Cl− is 3713.58 ppm and SO4−2 is 2,951.25 ppm with extremely high rates according to the World Health Organization (WHO). This study yields logical results which attributed to low rates of inflow discharges to Razzaza Lake, high rates of evaporation of 6.5 cm/month and due to low rates of rainfall for the studied period.
PubDate: 2022-04-22
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- An experimental study on silica fume and metakaolin doped portland
cement-based mortars using silica aerogel and air-entraining admixture-
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Abstract: Abstract Ordinary Portland Cement (OPC) is an expensive material and has negative effects on environmental health as it increases greenhouse gas emissions. These problems accelerate the search for substitute materials. Although metakaolin (MK) and silica fume (SF) show high potential as substitute materials, they are used at a limited rate in the construction industry. Considering plain Portland Cement may be insufficient in aggressive conditions, it was aimed to increase interest and awareness regarding the application by using two materials together. For this study, a critical substitution ratio (20%), was shared equally between metakaolin (10%) and silica fume (%10). In addition, silica aerogel (SA) (at 1, 2, 3, and 4%) and air-entraining admixture (AEA) (at 0.1, 0.4, 0.7, and 1%) were examined in terms of mechanical and thermal properties for the building construction in sustainable cities. Although these additives bring important advantages, their information is limited, especially in aggressive conditions. The 7 and 28 days compressive and flexural strengths and physical properties were found for 10 series. Also, the freezing–thawing and high-temperature tests were applied, and the scanning electron microscopy (SEM) analyzes were performed. According to the results, metakaolin and silica fume increased flexural strength by 5.67% and compressive strength by 8.07% due to their high pozzolanic properties. Also, 1% silica aerogel strengthened the cement paste and increased the compressive strength by 2%. Also, it maintained this performance after the durability tests. Although 0.1% air-entraining admixture decreased the strength results, it increased the compressive strength by 4% after freezing–thawing.
PubDate: 2022-04-21
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- Numerical study on the behaviour of resilient beam-column end plate
connection with dual structural fuse-
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Abstract: Abstract The beam-column connections are generally failed due to geometrical and material properties of connection under seismic conditions. Towards damage control of the connection, the forces must be mitigated away from the connection. The steel plates are used as a structural fuse that receives the forces from connection and fail first. The steel plates are not only used as dissipative fuse and also used as alternative force transfer path, which increases the moment capacity of the connection. In this research, a novel beam-column end-plate resilient connection is proposed. The connection is made resilient by incorporating the structural fuse. Two different types of fuses, such as single and dual fuse are modelled. The shape of the fuse has vital importance and it is modelled in the shape of an hourglass. The main objective of the current research is to study the effect of single fuse, dual fuse and combined action of fuse and damper in beam-column end-plate connection under cyclic loading. The objective is attained by two different types of studies such as component method and finite element analysis (FEA). The mechanical model is developed for the novel end-plate connection based on Eurocode 3. The parametric analysis is conducted using the component approach to study the effect of connection components such as end-plate thickness, bolt diameter and number of bolts. The appropriate geometrical configuration of the fuse plate is obtained using finite element analysis. The specimens are configured as five different forms based upon the number of fuses (single and dual fuse), the position of fuse (beam top flange alone, both top and bottom flange) and subjected to monotonic and cyclic loading. The moment of resistance, hysteresis response, stiffness, energy dissipation capacity and strain in the fuse were critically assessed in the present investigation. In the comparison of single and dual fuse, the ultimate moment of dual fuse is marginally higher than single fuse. The fuses present in the tension region directly took part in enhancing the moment capacity of connection whereas the fuses in the compression side were acted as a damping element which circuitously enhanced the moment capacity. Under cyclic conditions, it is good to have fuse on both sides (tension and compression) to get the benefit of both fuse and damping action.
PubDate: 2022-04-21
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- Evaluation of impact factor parameters for T-girder concrete bridge
considering multi-lane vehicle movement-
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Abstract: Abstract Many of the bridge design codes consider the vehicles’ dynamic effect by magnifying the static response of the bridge by a factor called impact factor (IM) or dynamic load allowance (DLA). In some of the current bridge design codes, the value of IM is specified based on a single parameter such as span length or fundamental frequency without mentioning the applicability of the same in multilane bridges. However, most of the analytical and experimental studies showed that the value of IM is influenced by a large number of parameters. In this paper, the effect of an increasing number of loading lanes, span length, vehicle weight, vehicle speeds, natural frequency, and vehicle loading positions on IM is investigated by using AASHTO (American Association of State Highway and Transportation Officials) and IRC (Indian Road Congress) vehicle loadings. Furthermore, the maximum IM is obtained from this study compared with the values specified in six different bridge design codes, and it is found that most of the current design codes overestimate the values of IM for straight T-girder concrete bridges with a good deck surface. The results are helpful to revisit the codal provisions.
PubDate: 2022-04-20
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