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The behavior of Shear Connectors in Steel-Normal Concrete Composite Structure under Repeated Loads
No full textIn today's construction industry, the use of composite beams is becoming more and more important, particularly for long-span bridges that must withstand repeated loads from moving automobiles. This work investigates the behavior of composite beams through experimentation. Six push-out steel-concrete specimens are made and tested with various levels of static and repetitive loading applied. The specimens are made of rolled steel sections that are joined to concrete decks on both sides by stud shear connectors. Two approaches”one static and the other repeating”applied a push-out load to two sets of samples. One has a stud shear connector measuring 16 mm, and the other measures 25 mm. Three specimens were made for each group. To determine the final load, one specimen from each group underwent a static push-out test in the first stage. In the subsequent phase, repeated loads of 0-80% and 25-80% of the maximum static load were applied to the remaining ones. The analysis process measured the variation in slip between the concrete decks and the steel section over several load cycles. It was found that the recorded slip values at the ultimate load increased about four times just before the failure. The recorded values of the residual slip at the end of each load cycle decreased with the increase in load cycle numbers. Also, it was found that the values of the residual slip depend on the values of the lower and upper limits of the load level. Doi: 10.28991/CEJ-2024-010-01-013 Full Text: PD
Geotechnical Properties of Fly Ash Blended Expansive Soil: A Review
No full textFly ash, an industrial byproduct, is used as both a building material and a soil stabilizer due to its pozzolanic properties. Moreover, it is challenging to extrapolate the results based on an inadequate amount of laboratory data because of the non-homogeneous character of the soil and the diversity in the chemical properties of fly ash. This review article fills in the gaps by providing an overview of the existing data related to the geotechnical characteristics of expansive soil stabilized with fly ash. The chemical composition of fly ash is provided in terms of oxides of various elements to help identify the kinds produced in different nations. Additionally, information about the physical and geotechnical characteristics of fly ash blended expansive soil is provided in order to comprehend the influence of the fly ash's chemical composition and the expansive soil's fines percentage. While the geotechnical property comprises Atterberg's limit, compaction, UCS, shear strength, free swelling index, CBR, and consolidation, the physical property includes specific gravity and durability. Shear modulus, damping ratio, and Poisson's ratio are used to describe the dynamic properties of the modified expansive soil. The published data in this field and the research gap will be identified by the researchers with the aid of this article. Doi: 10.28991/CEJ-SP2024-010-06 Full Text: PD
Experimental and Numerical Analysis of Concrete Columns under Axial Load Based on European Design Norms
No full textThis study presents a comparison between numerical and experimental results for reinforced concrete columns subjected to axial compression. Depending on the columns support and their organization within the structure, columns primarily work under either concentric or eccentric compression, respectively, bending in situations where horizontal actions such as wind or/and earthquakes are present in the structure. Different countries have specific design codes, and in this study, the calculation of columns is based on the European design codes, specifically EN 1992-1-1. As a common practice in most cases during research, tests are conducted using computational models, and based on the obtained results through the application of similarity theory, an attempt is made to transition to the actual behavior of structural elements. Therefore, this paper applies a logic of "almost real" testing, where two columns with square cross-sections were produced and tested. The columns had a rectangular base with cross-section dimensions of 20/20 cm and a height (L) of 300 cm, with a concrete strength of fcm,cube=61.80 MPa. They were reinforced with longitudinal reinforcement (4í˜12 mm) and had a tensile strength of ftm=588.10 MPa. Additionally, stirrups of í˜8 mm were placed at every sw=25 cm. Experimental results show a closer alignment with software calculations using SEISMOSOFT with an accuracy of 96%, while results according to EN 1992-1-1, based on simplified methods, show 64% for the Nominal Stiffness Method and 59% for the Curvature Method. Doi: 10.28991/CEJ-2024-010-02-05 Full Text: PD
Assessment of Ground Penetrating Radar for Pyrite Swelling Detection in Soils
No full textPyrite swelling in soils below buildings is a major issue. It leads to severe deformations in floor foundations. A survey is carried out at a selected site in the city of Laval, Quebec, to assess the usefulness of ground-penetrating radar (GPR) to detect deformations that may be indicative of the presence of pyrite. Four soil samples are taken from the aforementioned site to determine the soil type below the concrete slab. The results indicate the presence of limestone, moor clay, and shale sediments, which are prone to pyrite swelling. The GPR data were collected using the GSSI SIR 4000 with a high frequency antenna and processed using RADAN software. The GPR data indicate the presence of severe deformation in many locations of the concrete slab. The most important wave reflections indicative of pyrite swelling are the rebar reflections, showing interesting pushed-up and dropped-down reflections. These reflections appear in two forms. The first is the attenuated reflections that may occur due to pyrite-rich materials. The second is the high amplitude reflections that occur because of the air void, which can be formed due to heaving the concrete slab because of pyrite swelling. As a result, GPR appears to be an effective method for assessing and mapping the effect of pyrite swelling below concrete slabs. Doi: 10.28991/CEJ-2024-010-03-05 Full Text: PD
Post-Earthquake Liquefaction Vulnerability Mapping by Swedish Weight Sounding and Standard Penetration Test
No full textOn September 28, 2018, a 7.5-magnitude earthquake struck Palu City, Sigi Regency, and Donggala Regency in Central Sulawesi. It triggered liquefaction in different locations, including Balaroa, Petobo, Jono Oge, and Sibalaya; Typically, a significant number of studies conducted in the Balaroa region relied on a small amount of field test data to cover a rather large area. This research aims to map the liquefaction vulnerability by analyzing the data from both the Swedish Weight Sounding (SWS) and the Standard Penetration Test (SPT) in the Balaroa area. The SWS data was acquired through mapping using a systematic grid sampling method at ten different locations. The liquefaction potential was analyzed based on the N values by converting the SWS data (Nsw and Wsw) to Nvalues using the Inada equation (1960). Afterward, the analysis findings were verified by comparing them with the SPT data obtained from the same area. Based on the SWS and SPT data analysis results, all locations, including the adjacent areas, exhibited very high liquefaction vulnerability. In contrast, the SPT data indicated that the areas further from the spots exhibited low and very low liquefaction. The findings indicated that the occurrence of post-earthquake liquefaction in Balaroa and other regions within Palu City is prone to recurrence following earthquakes of specific magnitudes. Doi: 10.28991/CEJ-2024-010-07-09 Full Text: PD
Spatial and Temporal Analysis of Surface Water Pollution Indices Using Statistical Methods
No full textThis study was conducted to evaluate surface water quality using pollution indices including the organic pollution index (OPI), comprehensive pollution index (CPI), and water quality index (WQI), cluster analysis (CA), with the support of one-way analysis of variance (One-way ANOVA), and principal component analysis (PCA). Water quality data at 42 locations, with 22 water quality parameters including temperature, pH, turbidity, salinity, chloride, total dissolved solids, electrical conductivity, sulfate, dissolved oxygen, total suspended solids, biological oxygen demand, chemical oxygen demand, nitrite, nitrate, ammonium, orthophosphate, coliform, E. coli, arsenic, cadmium, lead, and copper, were used for the evaluation. The results showed that all the pollution indices fluctuated spatially and temporally. The OPI index ranged from slight organic pollution to heavy organic pollution, and the OPI values in February and April were higher than those in other months. OPI values were classified as moderate with 54.76% of the locations and heavily polluted with 45.24%. Assessment based on the CPI revealed that 16.7% and 83.3% of locations were classified as moderately contaminated and heavily contaminated, respectively. The WQI classified 45% of the locations as poor and 55% of the locations as having average water quality. In particular, the water quality in August, October, and December was better than that in other months. PCA results showed that eight polluting sources were responsible for 77.1% of the water quality variation. The main surface water polluting sources could be natural sources (riverbank erosion, rainwater runoff), wastewater (domestic, agricultural, and industrial), water discharge from the national park, and livestock areas. Local environmental management agencies need to have appropriate solutions to improve water quality. Future research should focus on the contribution sources to surface water degradation. Doi: 10.28991/CEJ-2024-010-06-07 Full Text: PD
Groundwater Quality Assessment in the Middle-Upper Pleistocene Aquifer
No full textThe study was conducted to assess groundwater quality and identify the main pollution sources of groundwater in Hau Giang province, Vietnam. Groundwater samples were collected at five locations (GW1-GW5) at qp2-3 aquifer in May and October 2022. Principal component analysis (PCA), cluster analysis (CA), water pollution index (WPI), and groundwater quality index (GWQI) were applied in the study. The results revealed that the groundwater quality was influenced by TDS, NH4+-N, permanganate index, and Fe. On the basis of WPI, GW2 and GW3 had the lowest water quality, exceeding a value of 1. The results of GWQI showed that groundwater quality was divided into three categories (excellent, poor, and unsuitable for drinking) in May and four categories (good, poor, very poor, and unsuitable for drinking) in October. The study also revealed seasonal variations in groundwater quality, particularly in GW5 (Vi Thuy district, Hau Giang, Vietnam). The CA results formed four water quality groups in both periods based on the similarity of groundwater parameters. PCA results presented that the three PCs explained 79.55% of the variation in groundwater quality. Three potential sources of pollution are derived from the discharge of wastewater (domestic, industrial, and agricultural), landfilling, and seawater intrusion. Doi: 10.28991/CEJ-2024-010-07-018 Full Text: PD
Estimation of Soil Loss using Remote Sensing Data in a Regional Tropical Humid Catchment Area
No full textSoil erosion has been and continue to be a major threat to environmental degradation especially in the developing countries. Accurate estimation of soil loss will provide reliable information in the management and mitigation solutions to soil erosion. In this study, the soil loss in an erosion prone Anambra State of South East region of Nigeria was estimated. Due to the complex nature of the catchment characteristics of Anambra State, soil loss cannot be estimated precisely by mere application of conventional soil erosion model. Hence a site-specific methodology was developed and applied. Revised Universal Soil Loss Equation (RUSLE) was integrated with the Geographic Information System (GIS) of the environment using remote sensing to build the model. 40-years rainfall data was collated from the Nigeria Meteorological Agency and analyzed. The various parameter of RUSLE which includes: Rainfall Erosivity (R), Soil Erodibility (K), Topography (LS), Land Use and Land Cover (C), and Erosion Control practices (P) were developed and imposed into ArcGIS 10.6 to estimate the amount of annual soil loss in the area. The result indicated that about 27.58km2 (0.59%) of the study area have very low erosion rate of 0 – 5 t ha1year-1 , while the rates of erosion in 1311.52km2 (28.01%), 538.59km2 (11.50%), 1649.08km2 (35.22%), 959.09km2 (20.48%), and 196.76km2 (4.20%) of the study area are 5–10, 10–15, 15–25, 25–50 and >50 t ha-1year-1respectively. This knowledge will help decision makers in managing the land degradation problems in Anambra State of Nigeria. Doi: 10.28991/CEJ-2024-010-07-014 Full Text: PD
Evaluating Partial Safety Factors for Shear Strength in Bearing Capacity Calculations for Cohesionless Soils
No full textCalculating bearing capacity is critical when designing shallow foundations. Many countries use limit state design (LSD) as the standard method for geotechnical design. The paper aims to develop realistic LSD partial factors for bearing capacity calculations of shallow foundations on cohesionless soils based on full-scale model tests. The experimental setup consisted of a hydraulic jack, concrete footing, sand samples, and pressure cells placed in a cylindrical wall. Fifteen sand samples were tested and classified by gradation and relative density. Settlement curves were plotted for each sample under an increasing load. The measured ultimate bearing stresses were found to be higher than theoretical values calculated using traditional methods. This indicates that the traditional approach is conservative. The suggested safety factor for the internal friction angle in cohesionless soils (γtan(ϕ)= 1.10) is notably lower than the values specified in Eurocode 7 at 1.25 and the Egyptian code of practice at 1.30. The proposed LSD partial factors allow for more economical designs than traditional factors while maintaining safety. The full-scale model-testing approach is novel and provides realistic factors directly applicable to Egyptian codes. The results are satisfactory and reasonable for the geotechnical design of shallow foundations on cohesionless soils. Doi: 10.28991/CEJ-2024-010-07-015 Full Text: PD
Bond-Slippage Characteristics between Carbon Fiber Reinforced Polymer Sheet and Heat-Damaged Geopolymer Concrete
No full textThe present study investigates the behavior of bond slip between carbon fiber reinforced polymer (CFRP) sheets and heat-damaged geopolymer concrete specimens that have been exposed to various elevated temperatures (20°C, 200°C, 400°C, and 600°C). The research aims to address the challenges posed by elevated temperatures on the bond strength and to highlight our original achievements in understanding and mitigating these effects. To assess the effect of different CFRP bonding widths and lengths, geopolymer concrete specimens were cast and bonded to sheets of CFRP. A total of 32 samples were tested under double-shear tension, examining the mechanical properties of geopolymer concrete, failure modes, bond force-slip curves, ultimate bond force and slip, stiffness, energy absorption, and scanning electron microscopy (SEM) analysis. The study found that temperatures up to 200°C caused a slight decline in mechanical properties and bond-slip behavior, with a 5% decrease in bond force and slippage. At 400°C, bond force and slippage reduced by 16%. Exposure to 600°C led to a significant 42% reduction in bond-slip behavior. The developed bond slippage model showed good agreement with experimental results, providing a valuable tool for predicting bond behavior under high-temperature conditions. Doi: 10.28991/CEJ-2024-010-07-03 Full Text: PD