Pub Date : 2020-12-07DOI: 10.1080/14488353.2020.1854942
Adamu Mulatu, Emer Tucay Quezon, O. Gudina
ABSTRACT During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial sector that produces huge waste. Thus, the main purpose of this study is to evaluate the combined effects of marble waste dust filler and Superpave aggregate gradation on the performance of HMA. Based on the Marshall Mix design, seventy-two (72) specimens were produced from three below-restricted zone (BRZ) of Superpave gradation (BRZ4, BRZ5, & BRZ6) by using the 0.45 power chart. The design gradation obtained to be BRZ5 with 4.96% OBC with corresponding values 9.13 KN of stability, 2.96 mm of flow, 73.51% of VFA, 15.73% of VMA, 2.308 gm/cm3, of bulk density and 4% of air void. The crushed stone dust filler was partially replaced by Marble Waste Dust filler (under No. 200 sieve) at replacement rate of (1%, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5%) by keeping design gradation and OBC constant. The test showed satisfactory results. The Marshall mix design parameters of all mixtures are within specification limit under international and local specifications. Marble waste dust filler when blended with a BRZ of Superpave gradation indicated a substantial effect on Marshall stability with 10.18 KN value at 3% MWD filler content.
在新产品的制造过程中，各种废物的排放和储存造成了恶劣的环境问题。大理石加工厂是产生大量废物的工业部门之一。因此，本研究的主要目的是评价大理石废尘填料和Superpave骨料级配对HMA性能的综合影响。基于Marshall Mix设计，采用0.45功率图从Superpave级配的BRZ4、BRZ5、BRZ6三个限下区(BRZ)中提取72个试件。得到的设计级配为BRZ5, OBC为4.96%，稳定性9.13 KN，流量2.96 mm, VFA为73.51%，VMA为15.73%，容重2.308 gm/cm3，空隙率为4%。在保持设计级配和OBC不变的情况下，将石粉填料部分替换为大理石废尘填料(200号筛下)，替换率分别为(1%、1.5、2、2.5、3、3.5、4、4.5、5%)。试验结果令人满意。所有混合物的马歇尔混合设计参数均在国际和国内规范的规格范围内。掺加Superpave级配BRZ的大理石废尘填料在掺量为3%时，对Marshall稳定性有显著影响，其值为10.18 KN。
{"title":"Evaluation of the HMA performance using combined effects of marble waste dust filler and superpave aggregate gradation","authors":"Adamu Mulatu, Emer Tucay Quezon, O. Gudina","doi":"10.1080/14488353.2020.1854942","DOIUrl":"https://doi.org/10.1080/14488353.2020.1854942","url":null,"abstract":"ABSTRACT During the fabrication of new products, a variety of wastes discharged and stored by causing harsh environmental problems. The marble processing plant is amongst the industrial sector that produces huge waste. Thus, the main purpose of this study is to evaluate the combined effects of marble waste dust filler and Superpave aggregate gradation on the performance of HMA. Based on the Marshall Mix design, seventy-two (72) specimens were produced from three below-restricted zone (BRZ) of Superpave gradation (BRZ4, BRZ5, & BRZ6) by using the 0.45 power chart. The design gradation obtained to be BRZ5 with 4.96% OBC with corresponding values 9.13 KN of stability, 2.96 mm of flow, 73.51% of VFA, 15.73% of VMA, 2.308 gm/cm3, of bulk density and 4% of air void. The crushed stone dust filler was partially replaced by Marble Waste Dust filler (under No. 200 sieve) at replacement rate of (1%, 1.5, 2, 2.5, 3, 3.5, 4, 4.5 and 5%) by keeping design gradation and OBC constant. The test showed satisfactory results. The Marshall mix design parameters of all mixtures are within specification limit under international and local specifications. Marble waste dust filler when blended with a BRZ of Superpave gradation indicated a substantial effect on Marshall stability with 10.18 KN value at 3% MWD filler content.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-12-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1854942","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43753718","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 : 2020-10-25DOI: 10.1080/14488353.2020.1838419
Nahida Nisar, J. A. Bhat
ABSTRACT Reinforcement corrosion in concrete has become a major factor affecting durability of reinforced concrete structures. Corrosion of reinforcement is a continuous process. It cannot be eliminated completely. But its rate can be prevented with the help of corrosion inhibitors, either by acting as a barrier, by forming an adsorbed layer on the reinforcement surface or by retarding the cathodic or anodic processes of corrosion. The hazardous effects of synthetic inhibitors have led to the utilisation of alternative non-toxic, eco-friendly plant extracts, generally known as green corrosion inhibitors. The study aims to investigate the effect of Rice Husk Ash (RHA) as a green corrosion inhibitor on the durability of reinforced concrete. The compressive strength, carbonation depth and corrosion rate of RHA concrete has been studied. The results showed that the compressive strength increased with the increase in percentage of RHA upto 15% replacement of cement. However, a decrease in compressive strength was noticed from 15 to 20% replacement. It was also observed that the carbonation depth gets increased with the increase in percentage of RHA. From the corrosion tests, it was observed that the corrosion rate decreases with the increase in RHA percentage, hence increasing the inhibition efficiency of the concrete.
{"title":"Experimental investigation of Rice Husk Ash on compressive strength, carbonation and corrosion resistance of reinforced concrete","authors":"Nahida Nisar, J. A. Bhat","doi":"10.1080/14488353.2020.1838419","DOIUrl":"https://doi.org/10.1080/14488353.2020.1838419","url":null,"abstract":"ABSTRACT Reinforcement corrosion in concrete has become a major factor affecting durability of reinforced concrete structures. Corrosion of reinforcement is a continuous process. It cannot be eliminated completely. But its rate can be prevented with the help of corrosion inhibitors, either by acting as a barrier, by forming an adsorbed layer on the reinforcement surface or by retarding the cathodic or anodic processes of corrosion. The hazardous effects of synthetic inhibitors have led to the utilisation of alternative non-toxic, eco-friendly plant extracts, generally known as green corrosion inhibitors. The study aims to investigate the effect of Rice Husk Ash (RHA) as a green corrosion inhibitor on the durability of reinforced concrete. The compressive strength, carbonation depth and corrosion rate of RHA concrete has been studied. The results showed that the compressive strength increased with the increase in percentage of RHA upto 15% replacement of cement. However, a decrease in compressive strength was noticed from 15 to 20% replacement. It was also observed that the carbonation depth gets increased with the increase in percentage of RHA. From the corrosion tests, it was observed that the corrosion rate decreases with the increase in RHA percentage, hence increasing the inhibition efficiency of the concrete.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1838419","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42750818","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 : 2020-10-21DOI: 10.1080/14488353.2020.1835148
A. Alzoubi, D. Ghunimat, M. Al-Rawashdeh, Shadi Hanandeh
ABSTRACT The large quantities of wastes resulting from water purification process (known as sludge) are increasingly becoming a big concern at some of developing countries, where no proper disposal options are available. The traditional practices of sludge disposal through dumping in landfills have become an ecological, environmental and financial burden. This is due to the daily operation, limited capacity of landfills, and negative impacts on soil, climate, surface and ground water. Hence, the goal of this research is to investigate the possibility of using incinerated sludge produced from water purification plants in construction field, and analyzing its effect on mechanical properties of concrete as one of sludge management options. Sludge was incinerated at a temperature of 800°C for two hours, grinded, sieved and replaced by fine aggregate at percentages of 5%, 10%, 15%, and 20% in concrete mixes. XRD and XRF tests were performed to identify crystalline phases and chemical composition of the sludge. The effect of using the incinerated sludge on workability, density, compressive and flexural strengths of concrete at curing ages of 7, and 28 days was investigated. The results showed a significant improvement in compressive and flexural strengths for all samples containing sludge for both curing ages in comparison to control samples, while a reduction in workability was observed.
{"title":"The potential of using water purification wastes as fine aggregates in concrete mixes: an initial study","authors":"A. Alzoubi, D. Ghunimat, M. Al-Rawashdeh, Shadi Hanandeh","doi":"10.1080/14488353.2020.1835148","DOIUrl":"https://doi.org/10.1080/14488353.2020.1835148","url":null,"abstract":"ABSTRACT The large quantities of wastes resulting from water purification process (known as sludge) are increasingly becoming a big concern at some of developing countries, where no proper disposal options are available. The traditional practices of sludge disposal through dumping in landfills have become an ecological, environmental and financial burden. This is due to the daily operation, limited capacity of landfills, and negative impacts on soil, climate, surface and ground water. Hence, the goal of this research is to investigate the possibility of using incinerated sludge produced from water purification plants in construction field, and analyzing its effect on mechanical properties of concrete as one of sludge management options. Sludge was incinerated at a temperature of 800°C for two hours, grinded, sieved and replaced by fine aggregate at percentages of 5%, 10%, 15%, and 20% in concrete mixes. XRD and XRF tests were performed to identify crystalline phases and chemical composition of the sludge. The effect of using the incinerated sludge on workability, density, compressive and flexural strengths of concrete at curing ages of 7, and 28 days was investigated. The results showed a significant improvement in compressive and flexural strengths for all samples containing sludge for both curing ages in comparison to control samples, while a reduction in workability was observed.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1835148","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43039212","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 : 2020-10-20DOI: 10.1080/14488353.2020.1835143
Mohsen Aboutalebi Esfahani, Vahid Mirian
ABSTRACT Glass fibre with high tensile strength and Ethylene Vinyl Acetate (EVA) polymer may change Stone Matrix Asphalt (SMA) performance significantly due to its good performance. Therefore, the study’s main objective is to evaluate these two additives’ performances and their combination on SMA. Thus, modified bitumen’s physical properties with 3, 4 and 5% of EVA and mechanical properties of SMA made by 3, 4 and 5% of EVA and 0.1%, 0.2% and 0.3% of glass fibre are investigated. For this purpose, penetration, softening point, rotational viscosity, dynamic shear rheometer, resilient modulus, dynamic creep, and fatigue tests are performed. The results demonstrate that the performance graded of modified bitumen with an optimum value of 4% EVA is improved as two classes, leading to a significant improvement in the SMA performance. However, the performance of SMA containing 0.2% and 0.3% of glass fibre decreases severely due to the fragility of the fibres. The performance of the mixture in 0.1% of the fibres is slightly improved due to the reinforcement of the bitumen mortar and the lack of effect of the fibres on the overall structure of the mixture. Also, only the combination of 4% EVA with 0.1% glass fibre gives an acceptable result.
{"title":"Evaluation of glass fibres, ethylene vinyl acetate and their combination on stone mastic asphalt","authors":"Mohsen Aboutalebi Esfahani, Vahid Mirian","doi":"10.1080/14488353.2020.1835143","DOIUrl":"https://doi.org/10.1080/14488353.2020.1835143","url":null,"abstract":"ABSTRACT Glass fibre with high tensile strength and Ethylene Vinyl Acetate (EVA) polymer may change Stone Matrix Asphalt (SMA) performance significantly due to its good performance. Therefore, the study’s main objective is to evaluate these two additives’ performances and their combination on SMA. Thus, modified bitumen’s physical properties with 3, 4 and 5% of EVA and mechanical properties of SMA made by 3, 4 and 5% of EVA and 0.1%, 0.2% and 0.3% of glass fibre are investigated. For this purpose, penetration, softening point, rotational viscosity, dynamic shear rheometer, resilient modulus, dynamic creep, and fatigue tests are performed. The results demonstrate that the performance graded of modified bitumen with an optimum value of 4% EVA is improved as two classes, leading to a significant improvement in the SMA performance. However, the performance of SMA containing 0.2% and 0.3% of glass fibre decreases severely due to the fragility of the fibres. The performance of the mixture in 0.1% of the fibres is slightly improved due to the reinforcement of the bitumen mortar and the lack of effect of the fibres on the overall structure of the mixture. Also, only the combination of 4% EVA with 0.1% glass fibre gives an acceptable result.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1835143","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43059791","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 : 2020-09-12DOI: 10.1080/14488353.2020.1816638
M. Zaki, Amira Tobaa, A. Shehata, Farid Mohamed, Ramy Khalef, Yomna Hagras, Reem Abou-Ali, M. Farag, A. Ghaly, Magdi Madi, E. Sayed-Ahmed, Yosra El-Maghraby, M. Abou-Zeid
ABSTRACT In this study an attempt is taken to evaluate the performance of basalt FRP bars compared with carbon FRP bars and conventional steel bars. Specimens of reinforced concrete will be casted to fulfil this comparison. These beams will comprise a common top reinforcement, stirrups spacing, and concrete properties. The difference is in the bottom reinforcement where it was once steel, Carbon FRP, Basalt FRP, and a hybrid of Basalt FRP and steel. These beams were tested for their behaviour under a flexural load through a four-point bending test. The remaining specimens were casted as columns with common stirrups spacing, and concrete properties. The behaviour of Basalt FRP, Carbon FRP, and steel reinforcement will be tested upon the application of an axial compressive load. The bonding strength between concrete and the different candidate bars is tested through the bond pull-out test. Furthermore, tests will be conducted on the thermal, chemical, and mechanical properties of the individual bars. This study is expected to yield an evaluation of the main characteristics of the newly developed Basalt FRP bars and an identification of the key differences and limitations of using BFRP in concrete structures in relation to CRFP and traditional steel reinforcement of concrete structure.
{"title":"Potential advantages of basalt FRP bars compared to carbon FRP bars & conventional steel","authors":"M. Zaki, Amira Tobaa, A. Shehata, Farid Mohamed, Ramy Khalef, Yomna Hagras, Reem Abou-Ali, M. Farag, A. Ghaly, Magdi Madi, E. Sayed-Ahmed, Yosra El-Maghraby, M. Abou-Zeid","doi":"10.1080/14488353.2020.1816638","DOIUrl":"https://doi.org/10.1080/14488353.2020.1816638","url":null,"abstract":"ABSTRACT In this study an attempt is taken to evaluate the performance of basalt FRP bars compared with carbon FRP bars and conventional steel bars. Specimens of reinforced concrete will be casted to fulfil this comparison. These beams will comprise a common top reinforcement, stirrups spacing, and concrete properties. The difference is in the bottom reinforcement where it was once steel, Carbon FRP, Basalt FRP, and a hybrid of Basalt FRP and steel. These beams were tested for their behaviour under a flexural load through a four-point bending test. The remaining specimens were casted as columns with common stirrups spacing, and concrete properties. The behaviour of Basalt FRP, Carbon FRP, and steel reinforcement will be tested upon the application of an axial compressive load. The bonding strength between concrete and the different candidate bars is tested through the bond pull-out test. Furthermore, tests will be conducted on the thermal, chemical, and mechanical properties of the individual bars. This study is expected to yield an evaluation of the main characteristics of the newly developed Basalt FRP bars and an identification of the key differences and limitations of using BFRP in concrete structures in relation to CRFP and traditional steel reinforcement of concrete structure.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1816638","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48232746","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 : 2020-09-12DOI: 10.1080/14488353.2020.1816639
M. Mahmoodian
ABSTRACT Failure of in-service oil and gas steel pipelines can have disastrous environmental, social and economic impacts. Preventing or alleviating those negative impacts requires a methodology to predict the service life of corroded steel pipes that enables implementing preventive maintenance and repairs measures. Such predictions involve uncertainty and vary in time. This paper puts forward a time-variant reliability-based approach to assess the failure of corroded offshore pipelines. The proposed approach accounts for the uncertainty in the corrosion rate and mechanical characteristics of pipes. Two methods are proposed: One that employs the Monte Carlo sampling and one that is based on the first-order reliability method. The methodology is then applied to three corroded offshore gas pipelines located in India and the time-variant failure probability is estimated considering target reliability. Next, variability and sensitivity analyses are conducted to identify the most influential sources of uncertainty on the failure probability of pipelines. It can be asserted that corrosion rate has a substantial role in estimating the structural reliability of pipelines.
{"title":"Structural reliability assessment of corroded offshore pipelines","authors":"M. Mahmoodian","doi":"10.1080/14488353.2020.1816639","DOIUrl":"https://doi.org/10.1080/14488353.2020.1816639","url":null,"abstract":"ABSTRACT Failure of in-service oil and gas steel pipelines can have disastrous environmental, social and economic impacts. Preventing or alleviating those negative impacts requires a methodology to predict the service life of corroded steel pipes that enables implementing preventive maintenance and repairs measures. Such predictions involve uncertainty and vary in time. This paper puts forward a time-variant reliability-based approach to assess the failure of corroded offshore pipelines. The proposed approach accounts for the uncertainty in the corrosion rate and mechanical characteristics of pipes. Two methods are proposed: One that employs the Monte Carlo sampling and one that is based on the first-order reliability method. The methodology is then applied to three corroded offshore gas pipelines located in India and the time-variant failure probability is estimated considering target reliability. Next, variability and sensitivity analyses are conducted to identify the most influential sources of uncertainty on the failure probability of pipelines. It can be asserted that corrosion rate has a substantial role in estimating the structural reliability of pipelines.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1816639","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46400235","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 : 2020-09-03DOI: 10.1080/14488353.2020.1813924
Hai-tao Wang, Haoyu Sun, Jiayu Shen, W. Fan
ABSTRACT Most hydraulic concrete structures are in complex stress state. In order to study the effect of dynamic action on properties of hydraulic concrete under biaxial tension-compression, hydraulic concrete specimens were subjected to dynamic biaxial tension-compression tests were conducted at 6 different tension-compression ratios of 0 (uniaxial compression), 0.05:-1, 0.1:-1, 0.25:-1, 0.5:-1, ∞ (uniaxial tension) as well as 4 different strain rates of 10−5/s, 10−4/s, 10−3/s and 10−2/s. The failure mode, ultimate strength, peak strain and stress-strain curve under different tension-compression ratios and strain rates were measured. According to test data, the ultimate strength, as well as deformation properties, was analysed in terms of tension-compression ratio and strain rate. The failure criterions of hydraulic concrete under dynamic biaxial tension-compression stress state were established in principal stress space and octahedral stress space, respectively, providing experimental and theoretical reference for the design and maintenance of hydraulic structures. The results of the research on the ultimate strength and failure criterion of ordinary concrete, wet sieve concrete and air-entrained concrete under biaxial stress state were compared with the experimental results of this paper, proving the feasibility of the failure criterion proposed in this paper.
{"title":"Experimental study on dynamic biaxial tension-compression properties of hydraulic concrete","authors":"Hai-tao Wang, Haoyu Sun, Jiayu Shen, W. Fan","doi":"10.1080/14488353.2020.1813924","DOIUrl":"https://doi.org/10.1080/14488353.2020.1813924","url":null,"abstract":"ABSTRACT Most hydraulic concrete structures are in complex stress state. In order to study the effect of dynamic action on properties of hydraulic concrete under biaxial tension-compression, hydraulic concrete specimens were subjected to dynamic biaxial tension-compression tests were conducted at 6 different tension-compression ratios of 0 (uniaxial compression), 0.05:-1, 0.1:-1, 0.25:-1, 0.5:-1, ∞ (uniaxial tension) as well as 4 different strain rates of 10−5/s, 10−4/s, 10−3/s and 10−2/s. The failure mode, ultimate strength, peak strain and stress-strain curve under different tension-compression ratios and strain rates were measured. According to test data, the ultimate strength, as well as deformation properties, was analysed in terms of tension-compression ratio and strain rate. The failure criterions of hydraulic concrete under dynamic biaxial tension-compression stress state were established in principal stress space and octahedral stress space, respectively, providing experimental and theoretical reference for the design and maintenance of hydraulic structures. The results of the research on the ultimate strength and failure criterion of ordinary concrete, wet sieve concrete and air-entrained concrete under biaxial stress state were compared with the experimental results of this paper, proving the feasibility of the failure criterion proposed in this paper.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1813924","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48301847","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 : 2020-08-07DOI: 10.1080/14488353.2020.1798039
H. Ahmadvand, A. Habibi
ABSTRACT In this study, a new method called Second-order Consistent Exponential Approximation (SCEA) is developed to generate the high-quality nonlinear approximation of the structural problems. For this purpose, some important parameters are designed by employing design sensitivities to enhance its consistency with various structural optimisation problems. In the optimisation process, the design variables for which sensitivity of the objective function is zero, are eliminated in the corresponding iteration. In addition, in approximating the design constraints, the zero design sensitivities are limited to a small value. In the presented approach, the primary optimisation problem is replaced with a sequence of explicit sub-problems. Each sub-problem is efficiently solved using the sequential quadratic programming (SQP) algorithm. For reducing computational cost and enhancing the efficiency and capability of the proposed method, a corrective technique is applied for tolerance on the constraint violation, the function value, and the design variables in the SQP algorithm. Several structural examples and highly nonlinear problems were utilised to demonstrate the efficiency of the proposed method. Optimal solutions were compared to the conventional approximation methods and some of the metaheuristic approaches. Results illustrate that the accuracy of the optimum design is improved and the rate of the convergence speeds up.
{"title":"A new second-order approximation method for optimum design of structures","authors":"H. Ahmadvand, A. Habibi","doi":"10.1080/14488353.2020.1798039","DOIUrl":"https://doi.org/10.1080/14488353.2020.1798039","url":null,"abstract":"ABSTRACT In this study, a new method called Second-order Consistent Exponential Approximation (SCEA) is developed to generate the high-quality nonlinear approximation of the structural problems. For this purpose, some important parameters are designed by employing design sensitivities to enhance its consistency with various structural optimisation problems. In the optimisation process, the design variables for which sensitivity of the objective function is zero, are eliminated in the corresponding iteration. In addition, in approximating the design constraints, the zero design sensitivities are limited to a small value. In the presented approach, the primary optimisation problem is replaced with a sequence of explicit sub-problems. Each sub-problem is efficiently solved using the sequential quadratic programming (SQP) algorithm. For reducing computational cost and enhancing the efficiency and capability of the proposed method, a corrective technique is applied for tolerance on the constraint violation, the function value, and the design variables in the SQP algorithm. Several structural examples and highly nonlinear problems were utilised to demonstrate the efficiency of the proposed method. Optimal solutions were compared to the conventional approximation methods and some of the metaheuristic approaches. Results illustrate that the accuracy of the optimum design is improved and the rate of the convergence speeds up.","PeriodicalId":44354,"journal":{"name":"Australian Journal of Civil Engineering","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2020-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/14488353.2020.1798039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45000533","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 : 2020-07-25DOI: 10.1080/14488353.2020.1786989
K. Doust, G. Battista, Peter G. Rundle
ABSTRACT With construction waste accounting for 40% of all waste produced in Australia, this paper evaluates front-end strategies to minimize physical site waste on Australian projects. Front-end strategies are those practices at the initial phase of the material logistics chain that will reduce or totally remove site waste, rather than simply treat the residual waste product. Following a global literature review, a qualitative methods approach using a pragmatic research framework was developed. The respondent sample for this research was from across the spectrum of Australian building and construction industry, varying from industry company directors to general superintendents. The paper observes that the historically rapid increase in construction waste will be exacerbated by the very real increasing risk of waste due to recovery from disaster damage (bush fire, flood and storm surge coupled with climate change). Increasingly intelligent front-end strategies that minimize waste have therefore become a high priority for action. It is concluded that the most effective way to reduce construction waste in Australia is via regulatory change, requiring policies and procedures that focus on front-end strategies. This paper explores some opportunities for action in the areas of management, design and procurement in line with the themes identified in the surveys
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Pub Date : 2020-07-21DOI: 10.1080/14488353.2020.1794298
N. Amatya, N. Anwar
ABSTRACT In the design of PCI-girder bridges, the application of various optimum design methodologies can result in significant cost savings and improved structural performance. However, most of the optimisation techniques focus on the individual components and the overall structural system of the superstructure of the bridge system. Limited studies are carried out in the context of longitudinal and transverse configurations of the members in a particular bridge system. This study identifies the optimum span for the PCI-girder expressway bridge system by adopting longitudinal and transverse arrangement of members as design variables while keeping the cross-section of the girder constant. Using an existing case study bridge structure located in Bangkok, selected parametric studies are carried out to achieve cost optimisation. It is observed that the optimum span range for the PCI-girder bridge is in the range of 25 m (82 ft) to 33 m (108 ft).
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