Pub Date : 2022-09-22DOI: 10.4038/engineer.v55i2.7507
P. T. R. S. Sugathadasa, M. D. De Silva, T. Kandanaarachchi, D.K.Y. Abeywardena
{"title":"Sensitivity Analysis of Motivation Factors of Engineers in Government Sector Construction Industry: A Case Study of Sri Lanka","authors":"P. T. R. S. Sugathadasa, M. D. De Silva, T. Kandanaarachchi, D.K.Y. Abeywardena","doi":"10.4038/engineer.v55i2.7507","DOIUrl":"https://doi.org/10.4038/engineer.v55i2.7507","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"191 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74183258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-22DOI: 10.4038/engineer.v55i2.7504
H. Mithila, N. Priyankara
: Construction of highway embankments over soft compressible soil or weak foundation soil results in many issues such as intolerable settlement, potential bearing failure, and global and local instability. In order to overcome these problems, many ground improvement methods are in use such as preloading with or without vertical drains, gravel compaction piles, piled embankments, etc. However, among these ground improvement techniques, Geosynthetic Reinforced Piled Embankment (GRPE) stands out due to its efficient load transfer mechanism and less construction time. In terms of design of GRPE, various researchers have introduced different methods based on different load transfer mechanisms. As such, there is an uncertainty among design engineers regarding the applicability of these design methods. This paper investigated the load transfer mechanism of GRPE using finite element analyses and currently available design methods were compared with the results of finite element modelling. Design methods were compared using output parameters of total load on a pile and geosynthetic tension by varying input parameters pile width, surcharge, soft soil stiffness, geosynthetic stiffness and embankment height. Based on the finite element analyses, the inconsistencies in the currently available design methods were identified.
{"title":"Review of Existing Design Methods of Geosynthetic Reinforced Piled Embankments (GRPE)","authors":"H. Mithila, N. Priyankara","doi":"10.4038/engineer.v55i2.7504","DOIUrl":"https://doi.org/10.4038/engineer.v55i2.7504","url":null,"abstract":": Construction of highway embankments over soft compressible soil or weak foundation soil results in many issues such as intolerable settlement, potential bearing failure, and global and local instability. In order to overcome these problems, many ground improvement methods are in use such as preloading with or without vertical drains, gravel compaction piles, piled embankments, etc. However, among these ground improvement techniques, Geosynthetic Reinforced Piled Embankment (GRPE) stands out due to its efficient load transfer mechanism and less construction time. In terms of design of GRPE, various researchers have introduced different methods based on different load transfer mechanisms. As such, there is an uncertainty among design engineers regarding the applicability of these design methods. This paper investigated the load transfer mechanism of GRPE using finite element analyses and currently available design methods were compared with the results of finite element modelling. Design methods were compared using output parameters of total load on a pile and geosynthetic tension by varying input parameters pile width, surcharge, soft soil stiffness, geosynthetic stiffness and embankment height. Based on the finite element analyses, the inconsistencies in the currently available design methods were identified.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"4 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79095417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-09-22DOI: 10.4038/engineer.v55i2.7503
H. Abeysiriwardana, N. Wijesekera
{"title":"Application of GIS and Logistic Regression for Flood Susceptibility Mapping in Nilwala River Basin, Sri Lanka","authors":"H. Abeysiriwardana, N. Wijesekera","doi":"10.4038/engineer.v55i2.7503","DOIUrl":"https://doi.org/10.4038/engineer.v55i2.7503","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"52 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91068663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7494
J. Sangeetha, J. Dalshica, M. Nasvi
Deep soil mixing (DSM) is a ground improvement technique used to improve the ground by in-situ stabilization of soft soil using stabilizers such as cement, lime and fly ash for depths greater than 1.5 m. To date, there are no studies focusing on developing a design guideline for DSM method to treat expansive soil using fly ash. Therefore, aim of this study was to develop a design guideline for DSM to stabilize expansive soil using fly ash as the stabilizer. Four different expansive soil samples obtained from Digana, Sri Lanka were treated with 10 25% fly ash by weight. A series of swell pressure tests were conducted on the untreated and treated samples to calculate the surface heave of the expansive soil – fly ash composite ground for different area ratio values (10 60%). Altogether sixteen heave versus area ratio design charts were developed for various fly ash contents and DSM column lengths (2 8 m). Further, spacing versus area ratio charts were developed for different diameters of the DSM columns for square and triangular arrangements. Based on the findings, it was noticed that incorporation of fly ash into expansive soil reduces the swell pressure significantly (53 – 86% reduction compared to the untreated expansive soil). The developed heave versus area ratio design charts can be used for the design and construction of DSM columns in expansive soils using fly ash as the stabilizer to maintain the total heave within the project specified limit. On the whole, DSM technique can be successfully used to treat expansive soils using fly ash as the stabilizer.
{"title":"Development of Design Guideline for Deep Soil Mixing (DSM) to Stabilize Expansive Soils using Fly Ash as the Stabilizer","authors":"J. Sangeetha, J. Dalshica, M. Nasvi","doi":"10.4038/engineer.v55i1.7494","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7494","url":null,"abstract":"Deep soil mixing (DSM) is a ground improvement technique used to improve the ground by in-situ stabilization of soft soil using stabilizers such as cement, lime and fly ash for depths greater than 1.5 m. To date, there are no studies focusing on developing a design guideline for DSM method to treat expansive soil using fly ash. Therefore, aim of this study was to develop a design guideline for DSM to stabilize expansive soil using fly ash as the stabilizer. Four different expansive soil samples obtained from Digana, Sri Lanka were treated with 10 25% fly ash by weight. A series of swell pressure tests were conducted on the untreated and treated samples to calculate the surface heave of the expansive soil – fly ash composite ground for different area ratio values (10 60%). Altogether sixteen heave versus area ratio design charts were developed for various fly ash contents and DSM column lengths (2 8 m). Further, spacing versus area ratio charts were developed for different diameters of the DSM columns for square and triangular arrangements. Based on the findings, it was noticed that incorporation of fly ash into expansive soil reduces the swell pressure significantly (53 – 86% reduction compared to the untreated expansive soil). The developed heave versus area ratio design charts can be used for the design and construction of DSM columns in expansive soils using fly ash as the stabilizer to maintain the total heave within the project specified limit. On the whole, DSM technique can be successfully used to treat expansive soils using fly ash as the stabilizer.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"6 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90102455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7482
M. Rekatheeban, H. Yapa
High performance concrete (HPC) is stronger/more durable than conventional concrete and its popularity has been widespread over the recent past. The composition of HPC is unique, for instance, it comprises high paste/aggregate volume, supplementary cementitious materials, etc. Consequently, some HPC characteristics are distinguished to be stern and one of those is shrinkage. For instance, HPC structures that are subjected to restrained conditions could experience undesirable non-structural cracking. In this context, this study assessed the restrained shrinkage behaviour of five HPC mixes conforming to the ASTM C1581 procedure. The mixes were designed for 50 MPa target cylinder compressive strength and comprised supplementary cementitious materials (SCMs) of 0-10% silica fume (SF) and 0-30% fly ash (FA). The results showed that the control and 10%SF/30%FA mixes had comparatively lower cracking potential under restrained conditions whereas the highest cracking potential was with the 10%SF/0%FA and 10%SF/10%FA mixes. Hence, shrinkage exaggerated with the addition of SF whereas that undesirability was compensated with the addition of FA. Meanwhile, the compressive strength of the control mix was enhanced approximately by 48% with the inclusion of 10%SF whilst the FA inclusion to the 10%SF mix reduced the compressive strength fairly proportional to the FA content. Overall, the strength varied in the range of 49 – 73 MPa. Mix 10%SF/20%FA had 26.5% higher compressive strength than the control mix and showed low risk on restrained shrinkage cracking. Hence, it was identified as a promising HPC combination. Similarly, 10%SF/30FA mix showed similar strength and crack potential characteristics to the control mix. That mix was accordingly identified as an ideal sustainable concrete mix for highstrength concrete applications.
{"title":"Restrained Shrinkage of High Performance Concrete Comprising Silica Fume and Fly Ash","authors":"M. Rekatheeban, H. Yapa","doi":"10.4038/engineer.v55i1.7482","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7482","url":null,"abstract":"High performance concrete (HPC) is stronger/more durable than conventional concrete and its popularity has been widespread over the recent past. The composition of HPC is unique, for instance, it comprises high paste/aggregate volume, supplementary cementitious materials, etc. Consequently, some HPC characteristics are distinguished to be stern and one of those is shrinkage. For instance, HPC structures that are subjected to restrained conditions could experience undesirable non-structural cracking. In this context, this study assessed the restrained shrinkage behaviour of five HPC mixes conforming to the ASTM C1581 procedure. The mixes were designed for 50 MPa target cylinder compressive strength and comprised supplementary cementitious materials (SCMs) of 0-10% silica fume (SF) and 0-30% fly ash (FA). The results showed that the control and 10%SF/30%FA mixes had comparatively lower cracking potential under restrained conditions whereas the highest cracking potential was with the 10%SF/0%FA and 10%SF/10%FA mixes. Hence, shrinkage exaggerated with the addition of SF whereas that undesirability was compensated with the addition of FA. Meanwhile, the compressive strength of the control mix was enhanced approximately by 48% with the inclusion of 10%SF whilst the FA inclusion to the 10%SF mix reduced the compressive strength fairly proportional to the FA content. Overall, the strength varied in the range of 49 – 73 MPa. Mix 10%SF/20%FA had 26.5% higher compressive strength than the control mix and showed low risk on restrained shrinkage cracking. Hence, it was identified as a promising HPC combination. Similarly, 10%SF/30FA mix showed similar strength and crack potential characteristics to the control mix. That mix was accordingly identified as an ideal sustainable concrete mix for highstrength concrete applications.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"30 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86368096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7488
M. Maheepala, R. L. Hewavitharana, M. Nasvi
{"title":"Combined Effect of Temperature and Salinity on the Triaxial Mechanical Behaviour of Geopolymers: An Experimental and Numerical Study","authors":"M. Maheepala, R. L. Hewavitharana, M. Nasvi","doi":"10.4038/engineer.v55i1.7488","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7488","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"1 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90372069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7484
R. M. D. Priyankara, I. Premaratne
{"title":"Review of Existing Transformer-Less PV Inverter Topologies and Design a Modified Topology to Reduce Leakage Current","authors":"R. M. D. Priyankara, I. Premaratne","doi":"10.4038/engineer.v55i1.7484","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7484","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"2 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78890816","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7486
H. P. Rathnayaka, D. Dasanayake, H. Yapa
Hydration of cement is exothermic and the consequent temperature development leads to non-structural cracking in immature concrete. The maximum internal temperature drop (T1) is a governing parameter towards thermal cracking, and for structural deigns, T1 values recommended in the codes of practice are commonly used. Past investigations show that such recommendations could be too conservative. Amid the complexity of concrete thermal behaviour, one good prediction option is to use numerical methods. In this light, this study attempted to formulate recommendations for T1 via finite element (FE) analysis. First, a commercial FE software was validated for two distinct experimental results and, second, the FE application was used to predict the temperature in concrete walls. The variables were: wall thickness (300 1000 mm); cement composition (350 560 kg/m3); and plywood/steel formwork types. Semi-adiabatic experiments were conducted to obtain the rate of heat evolution in concrete. The numerical results showed that the predicted T1 values were considerably lower than those recommended in two currently practiced guidelines. The observed disparity was in the range of 22% 34%. It was also shown that T1 could be further reduced by about 15% and 23.5% through supplementing the mixes with fly ash by 20% and 35%, respectively.
{"title":"Assessment of Time-dependent Temperature Behaviour in Immature Concrete Walls using Numerical Analysis","authors":"H. P. Rathnayaka, D. Dasanayake, H. Yapa","doi":"10.4038/engineer.v55i1.7486","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7486","url":null,"abstract":"Hydration of cement is exothermic and the consequent temperature development leads to non-structural cracking in immature concrete. The maximum internal temperature drop (T1) is a governing parameter towards thermal cracking, and for structural deigns, T1 values recommended in the codes of practice are commonly used. Past investigations show that such recommendations could be too conservative. Amid the complexity of concrete thermal behaviour, one good prediction option is to use numerical methods. In this light, this study attempted to formulate recommendations for T1 via finite element (FE) analysis. First, a commercial FE software was validated for two distinct experimental results and, second, the FE application was used to predict the temperature in concrete walls. The variables were: wall thickness (300 1000 mm); cement composition (350 560 kg/m3); and plywood/steel formwork types. Semi-adiabatic experiments were conducted to obtain the rate of heat evolution in concrete. The numerical results showed that the predicted T1 values were considerably lower than those recommended in two currently practiced guidelines. The observed disparity was in the range of 22% 34%. It was also shown that T1 could be further reduced by about 15% and 23.5% through supplementing the mixes with fly ash by 20% and 35%, respectively.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"28 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87537701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7493
M. B. A. Deemantha, G. De Silva
Hydrogen sulfide (H2S) corrosion is a common problem in oil, gas and Petrochemical/Chemical industries. This becomes a particularly dangerous form of corrosion in the industry as it occurs without any warning. Petroleum refining industry can be identified as one of the industries which faces the disastrous consequences of H2S corrosion. Most of the petroleum pipelines are made out of mild steel that is easily attacked by H2S corrosion. H2S corrosion begins with the synergistic effect of tensile force and H2S rich environment imposed on mild steel. This corrosion can only be detected using complicated inspection methods such as electro-chemical techniques, nondestructive test methods and optical testing methods etc. But, these techniques have become more complicated to inspect the corrosion due to different environments where the pipelines are set up. The main drawback of these techniques is that any damage that is detected has already occurred. Therefore, necessity of a model to predict the rate and behavior of H2S corrosion has been arising and being discussed for years. This article summarizes major factors affecting H2S corrosion, existing corrosion prediction models and their pros and cons. Furthermore, this paper reviews how corrosion kinetics involve in H2S corrosion and proposed corrosion mechanisms by researchers.
{"title":"A Study of Prediction of the Behavior of Hydrogen Sulfide Corrosion in Mild Steel Used for Petroleum Pipelines","authors":"M. B. A. Deemantha, G. De Silva","doi":"10.4038/engineer.v55i1.7493","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7493","url":null,"abstract":"Hydrogen sulfide (H2S) corrosion is a common problem in oil, gas and Petrochemical/Chemical industries. This becomes a particularly dangerous form of corrosion in the industry as it occurs without any warning. Petroleum refining industry can be identified as one of the industries which faces the disastrous consequences of H2S corrosion. Most of the petroleum pipelines are made out of mild steel that is easily attacked by H2S corrosion. H2S corrosion begins with the synergistic effect of tensile force and H2S rich environment imposed on mild steel. This corrosion can only be detected using complicated inspection methods such as electro-chemical techniques, nondestructive test methods and optical testing methods etc. But, these techniques have become more complicated to inspect the corrosion due to different environments where the pipelines are set up. The main drawback of these techniques is that any damage that is detected has already occurred. Therefore, necessity of a model to predict the rate and behavior of H2S corrosion has been arising and being discussed for years. This article summarizes major factors affecting H2S corrosion, existing corrosion prediction models and their pros and cons. Furthermore, this paper reviews how corrosion kinetics involve in H2S corrosion and proposed corrosion mechanisms by researchers.","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"11 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90782270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-06-10DOI: 10.4038/engineer.v55i1.7485
H. Sanjeewa, J. Appuhamy
{"title":"Prediction of the Residual Flexural Capacities of Deteriorated and Retrofitted Reinforced Concrete Members with Different Corrosion Conditions","authors":"H. Sanjeewa, J. Appuhamy","doi":"10.4038/engineer.v55i1.7485","DOIUrl":"https://doi.org/10.4038/engineer.v55i1.7485","url":null,"abstract":"","PeriodicalId":42812,"journal":{"name":"Engineer-Journal of the Institution of Engineers Sri Lanka","volume":"162 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2022-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73804233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：