Department of Civil Engineering

1. A comparative study of models for shear strength of reinforced concrete T-beams

Author:Liu, J;Gao, ZY


Abstract:Reinforced concrete T-beams are widely used in bridges where beams are cast integrally with deck sections to either side at the beam tops. Although it has been recognized by numerous experimental studies that flanges may have a significant contribution to the shear strength of reinforced concrete T-beams, they are neglected in most of the design codes. In this paper, the load paths to transfer shear force in T-beams are firstly investigated with the help of existing experimental tests. Compared with rectangular beams, an additional load path diverts the diagonal compression from the loading point and the end support, and it carries a portion of the shear force through the flange to the end support. In order to find a relatively reliable model to predict the shear strength of T-beams, a comparative study is carried out among five representative models selected from the literature by using a database with 233 reported T-beam tests. Parametric studies with individual test series are also performed for a detailed evaluation of the five models. It is found that a model proposed by Cladera et al. (i.e., Model [3] is one of the models producing the least scattered predictions. The average shear strength experimental-to-predicted ratio V-exp/V-pred is 1.06 with the coefficient of variation (COV) of 19.6%%. At the same time, it is shown that Model [3] exhibits uniform results across the entire range of experimental data without obvious bias. At the same time, Model [3] is one of the models requiring the least computational effort but with the largest range of applicability.
2. Experimental and Numerical Study on Impact of Double Layer Vegetation in Open Channel Flows

Author:Rahimi, HR;Tang, X;Singh, P


Abstract:This paper studies the effects of different types and configurations of double layer vegetation on the flow of open channels. The vegetation is simulated through cylindrical dowels with a diameter of 6.35 mm and heights of 10 and 20 cm, which represent short and tall dowels, respectively. Profiles for instantaneous velocities were obtained by acoustic Doppler velocimetry (ADV) at different locations around vegetation with multiple staggered and linear formations. The experiment covers a wide range of sparse to dense vegetation configurations. Furthermore, different flow depths were selected to simulate fully submerged cases for short vegetation and to capture the inflection of velocity over the mixing region between short and tall dowels. The results reveal that the velocity profile is mostly uniform at the depth of short vegetation in different configurations with various densities. The velocity starts to increase in the region near the top edge of short vegetation, followed by a significant increase through the height of tall vegetation to the free surface. Generally, the flow velocity behind the vegetation layer is significantly smaller than that in free regions adjacent to short and tall vegetation. The overall idea of the present study was to simulate the same sets of vegetation configurations using a K-epsilon model with mesh sensitivity analysis to capture inflections over the short vegetation region. The experimental investigations with a numerical study were explored for double layer vegetation, which was corroborated and found to have good agreement for different vegetation configurations. (C) 2019 American Society of Civil Engineers.
3. Material Characterization for Sustainable Concrete Paving Blocks

Author:Wang, XY;Chin, CS;Xia, J


Abstract:Recycled aggregates have been widely studied and used in concrete products nowadays. There are still many waste materials that can be used as recycled aggregates other than crushed concrete particles. This paper aims to study the property variations of sustainable concrete paving block incorporating different contents of construction wastes. Five different types of waste materials were used in this project, including: recycled concrete coarse aggregate (RCCA), recycled concrete fine aggregate (RCFA), crushed glass (CG), crumb rubber (CB), and ground granulated blast furnace slag (GGBS). According to the test results of the properties of blocks mixed with different levels of wastes materials, it is concluded that adding both RCCA and RCFA in the block can decrease its strength and increase the water absorption. The suggested replacement levels for RCCA and RCFA are 60%% and 20%%, respectively. Mixing crushed glass in the concrete paving blocks as a type of coarse aggregates can improve the blocks' strength and decrease the blocks' water absorption. Addition of crumb rubber causes a significant deterioration of blocks' properties except for its slip resistance.
4. Implementation of CIM-related technologies within transportation projects

Author:Guo, FY;Jahren, CT;Hao, JL;Zhang, C


Abstract:Technologies are continuously evolving and transportation agencies are always trying to find appropriate technologies to assist with their projects. However, it might be hard to answer what technologies and tools are appropriate for them to use and when to use those technologies and tools. Thus, the purpose of this study is to investigate leading transportation agencies' uses of various advanced technologies (e.g. geographic information system (GIS), light detecting and ranging (LiDAR), 3D engineered models, automatic machine guidance (AMG), mobile devices, intelligent compaction (IC), and electronic document management (EDM) system). Based on the 2 weeks of on-site visits to seven transportation agencies, benefits and lessons learned of using these technologies are summarized in the paper. Additionally, a framework is developed to suggest the proper occasions to use various technologies and manage the resulting data throughout the lifecycle of a transportation project.
5. Parametric investigation of polymethacrylate monolith synthesis and stability via thermogravimetric characterisation

Author:Acquah, C;Danquah, MK;Moy, CKS;Anwar, M;Ongkudon, CM


Abstract:Polymethacrylate monoliths are synthetic adsorbents with macroporous and mesoporous interconnected channels that can be engineered to target the hydrodynamic features of a wide range of molecular species. However, rigorous study into the effect of synthesis conditions on their thermal stability is limited. This work attempts to characterise the influence of key synthesis process variables on the stability of polymethacrylate monoliths using thermogravimetric analysis at a heating rate of 10 degrees C/min. Experimental results showed that the thermal stability of polymethacrylate monoliths increased with decreasing polymerisation temperature from 85 to 65 degrees C. Increasing the total porogen (P) to monomer (M) ratio increased the thermal stability of the monolith by >62%% and >50%% for P40/M60-P60/M40 and P60/M40-P80/M20, respectively. The impact of the initiator concentration, monomer variation, biporogen ratio, washing and activation of the monoliths was investigated. Nuclear magnetic resonance analyses conducted confirmed the hydrolysis of epoxy moieties on the monolith. (C) 2017 Curtin University of Technology and John Wiley & Sons, Ltd.
6. Numerical Study to Examine the Effect of Porosity on In-Flight Particle Dynamics

Author:Kamnis, S;Gu, S;Vardavoulias, M


Abstract:High velocity oxygen fuel (HVOF) thermal spray has been widely used to deposit hard composite materials such as WC-Co powders for wear-resistant applications. Powder morphology varies according to production methods while new powder manufacturing techniques produce porous powders containing air voids which are not interconnected. The porous microstructure within the powder will influence in-flight thermal and aerodynamic behavior of particles which is expected to be different from fully solid powder. This article is devoted to study the heat and momentum transfer in a HVOF sprayed WC-Co particles with different sizes and porosity levels. The results highlight the importance of thermal gradients inside the particles as a result of microporosity and how HVOF operating parameters need to be modified considering such temperature gradient.
7. Combinations of fungal and milling pretreatments for enhancing rice straw biogas production during solid-state anaerobic digestion

Author:Mustafa, AM;Poulsen, TG;Xia, YH;Sheng, KC


Abstract:Rice straw was pretreated by different combinations of physical (milling) and biological (incubation with Pleurotus ostreatus fungus) treatment to improve its biodegradability and biogas production during solid-state anaerobic digestion (SS-AD). Effects of milling (62 mm) and incubation time (10, 20 and 30 d), on lignin, cellulose, and hemicellulose degradation during fungal pretreatment and methane yield during digestion were assessed by comparison with untreated rice straw. Both incubation time and milling had significant impacts on both lignin removal during fungal pre-treatment and methane yield during digestion. A combination of fungal pretreatment at 30 days followed by milling prior to anaerobic digestion resulted in 30.4%% lignin removal, the highest selectivity value (the ratio between relative lignin removal and relative cellulose removal) of 4.22, and the highest methane yield of 258 L/kg VS. This was equivalent to a 165%% increase in methane yield from SS-AD compared to untreated rice straw. (C) 2016 Elsevier Ltd. All rights reserved.
8. Graphene oxide/PVC composite papers functionalized with p-Phenylenediamine as high-performance sorbent for the removal of heavy metal ions

Author:Khan, Zaheen Ullah ; Khan, Wasid Ullah ; Ullah, Bakhtar ; Ali, Wajid ; Ahmad, Bilal ; Yap, Pow-Seng

Source:Journal of Environmental Chemical Engineering,2021,Vol.9

Abstract:Due to the rapid industrialization, heavy metals contamination in the aquatic environment has become more serious. Thus, it is urgent to develop enhanced removal technology for heavy metals. Graphene oxide (GO) based composite paper-like materials have been widely applied for adsorption of heavy metals from wastewater. Herein, we fabricated for the first time an advanced, highly-ordered and homogenous PVC/PPD/GO paper-like material using a resin-infiltration technique. This process is complimentary to layer-by-layer assembly, where the assembling components are required to interact strongly (e.g., via hydrogen bonding or electrostatic attraction). The results showed that the composite papers could achieve high removal efficiency of the heavy metals from water. The amount of Pb(II) adsorbed at equilibrium as achieved by GO, PVC/GO-0.05, PVC/GO-0.08, PVC/PPD/GO-0.05 and PVC/PPD/GO-0.08 buckypapers were 17.61, 22.17, 25.41, 33.57 and 44.80 mg g−1, respectively. In addition, the effects of experimental factors (e.g. GO content, ionic strength of heavy metal ions, temperature and solution pH) on heavy metal adsorption were discussed. Furthermore, the as-prepared PVC/PPD/GO-0.08 composite papers exhibited superior stability and could be recycled more than 900 h based on their 15 regeneration cycles. The improved heavy metal removal efficiency was attributed to the enhanced morphology and the formation of micro- and nano-channels created by the entangled PPD/GO. The findings indicated that the PVC/PPD/GO composite buckypapers could be used as promising materials for the adsorption of heavy metals from wastewater. © 2021 Elsevier Ltd
9. Experimental Study of Smooth Asymmetric Compound Channels Flow: An Investigation of the Interaction of Flow Using Scaling Argument for Prediction of Overall Discharge


Source:IOP Conference Series: Earth and Environmental Science,2021,Vol.668

Abstract:A simple model for the apparent shear stress on the vertical interface between the floodplain and main channel in asymmetric smooth compound channels is proposed using experimental data obtained in this study. The turbulent structure, including Reynolds shear stress in asymmetric compound channel flows, is investigated for three different flow depths. The lateral distribution of the apparent shear stress obtained shows that the total apparent shear stress has a negative peak near the junction edge in the main channel. Furthermore, the intensity of the advection terms and the Reynold shear stress near the interface are investigated as the function of the bankfull height and floodplain width. The momentum transport due to Reynolds stress and secondary current between main channel and floodplain is finally modeled as depth ratio using scaling argument. The validation of the current model on three datasets shows an accurate prediction of overall discharge for the asymmetric smooth compound channels.
10. An improved method for predicting discharge of homogeneous compound channels based on energy concept

Author:Tang, XN


Abstract:Accurate estimation of flow discharge in a compound river channel is increasingly important in river management and hydro-environment design. In this paper, a new model is developed to improve the prediction of flow based on Energy Concept Method (ECM) and Weighted Divided Channel Method (WDCM) along with the apparent shear stress at the interface between main channel and floodplain. The new model is compared with a wide range of our experimental data and the data available in the literature. The 27 datasets used include homogenous symmetric channels (22 datasets) and asymmetric channels (5 datasets) with various aspect ratios [channel total width (B) at bankfull / main channel bottom (b) =1.5-15.8], and bed slopes (S-0 = 4.3 x 10(-4)-1.3 x 10(-2)). It was found that the new model has significantly improved the accuracy of flow prediction compared with the traditional Divided Channel Method (DCM), and has also considerably better results than the ECM and WDCM methods against all the datasets, particularly for relatively low flow depths of floodplain where the flow discharges are most difficult to predict correctly. The new model predicts the total discharge well for both symmetric and asymmetric channels, within an averaged relative error of about 5%%.
11. Sectional analysis for design of ultra-high performance fiber reinforced concrete beams with passive reinforcement

Author:Xia, J;Chan, T;Mackie, KR;Saleem, MA;Mirmiran, A


Abstract:Sectional flexural analysis, as performed in normal strength concrete design, requires uniaxial constitutive models. For ultra-high performance fiber reinforced concrete (UHPFRC), the constitutive model tensile backbone varies with section heights for different flexural members, due to the size-dependent stress-crack opening relation used to derive it. In this paper, several simplified size-independent constitutive models were investigated. For unreinforced sections with heights between 51 mm and 1067 mm, the elastic-perfectly-plastic tension model leads to conservative ultimate moment prediction (or results within 5%%) when compared to that obtained by the size-dependent model. For reinforced sections, the difference between the two models is affected by the reinforcing condition and is even smaller than the unreinforced cases. By assuming an elastic-perfectly-plastic tension model, the flexural strength of rectangular or T section UHPFRC beams was estimated analytically. The flexural strengths are greatly influenced by the reinforcement ratio and yielding strength of the longitudinal reinforcement. Including shear strength predictive equations from past research, the load capacity and failure mode for rectangular and T beams are presented in a design chart. The impact of several factors on UHPFRC beam flexural responses were investigated, such as different compressive strength, curing conditions, and anisotropic fiber orientation distributions. The load-deflection relationships generated from beam flexural analysis were compared to experimental results for both unreinforced and reinforced beams, with or without fiber alignment. Factors affecting the first crack strength in tension (i.e., fiber orientation distribution) had greater impact on the flexural strength of UHPFRC beams than the effect of using a size-dependent model.
12. Lateral Shear Layer and Its Velocity Distribution of Flow in Rectangular Open Channels

Author:Xiaonan Tang

Source:Journal of Applied Mathematics and Physics,2019,Vol.7

Abstract:The lateral velocity distributionof flow in the shear layer of open channel is required to many problems in river and eco-environment engineering, e.g.distribution of pollutant dispersion, sediment transport and bank erosion, and aquatic habitat. It isnot well understood about how the velocity varies laterally in the wallboundary layer. This paper gives an analytical solution of lateral velocitydistribution in a rectangular open channel based on the depth-averaged momentumequation proposed by Shiono & Knight. The obtained lateral velocitydistributions in the wall shear layer are related to the two hydraulicparameters of lateral eddy viscosity ( λ )and depth-averaged secondary flow (Γ) for given roughened channels. Preliminaryrelationships between the above two parameters and the aspect ratio of channel, B / H , are obtained from two sets ofexperimental data. The lateral width ( δ )of the shear layer was investigated and found to relate to the λ and the bed friction factor ( f ), as described by Equation (2 6 ...
13. Textile-reinforced mortar external strengthening of corroded reinforced concrete beams

Author:Moy, Charles K.S. ; Oluwadahunsi, Silas

Source:Sustainable Construction Materials and Technologies,2019,Vol.3

Abstract:The need for reliable material techniques for the restoration of corrosion-damaged reinforced concrete (RC) elements cannot be over-emphasised, especially when considering the sustainability aspects of reinforced concrete structures. This investigation examines the application of basalt textile-reinforced mortar for external strengthening of corroded RC beams in flexure. In that regard, a set of reinforced concrete beams subjected to accelerated corrosion to 10%% and 20%% mass loss of the main steel bars at mid-span and were strengthened using TRM. In total, 7 beams were tested under four-point bending for the following conditions 1 control, 2 corroded and 4 strengthened. Two strengthening schemes were single ply TRM of equivalent surface area. The results show that corrosion had detrimental effects on load-carrying capacity, yield strength, as well as ductility of corroded beams. Strengthening schemes restored the load capacity of the 10%% corroded beams within a range of 105%% to 112%% of control load capacity. Recovery of the load carrying capacity was not achieved for the 20%% corroded beams. All the strengthened specimens ultimately failed by fibre reinforcement rupture, thus indicating full utilisation of composite action of the TRM. © 2019 International Committee of the SCMT conferences. All rights reserved.
14. BIM-based investigation of total energy consumption in delivering building products

Author:Zhang, C;Nizam, RS;Tian, L


Abstract:Considerable efforts have been made to reduce buildings' operational energy use over the last decades, but little attention has been paid to reduce the material transportation and construction energy. Focusing only on the operation phase forgoes the opportunity to reduce other building-related energy consumption, and even if the environmental impacts arising from construction and transportation are small as compared to the operation phases, its cumulative impact at the national level is of concern. The energy consumed by a building is divided into two parts embodied energy and operation energy. Further, the embodied energy is constituted of energy intensity of materials, energy consumed during transportation and energy consumed for construction. This paper proposes a methodology to integrate embodied energy consumption into a BIM platform and provides a seamless analysis based on available information. Plug-ins are developed to fulfill a convenient linkage between the BIM model and external databases. Simulation models are created, which can be used as templates for energy optimization during transportation and construction. By analyzing different resource combination scenarios, lower energy consumption can be achieved.
15. Hydraulic characteristics of open-channel flow with partially-placed double layer rigid vegetation

Author:Tang, XN;Rahimi, H;Guan, YT;Wang, YX


Abstract:Vegetation in watercourses can influence different aspects of flow structure, subsequently affecting many processes of flow, such as pollutant transportation, sediment deposition and hydrophyte habitat distribution. Vegetation often occurs on one side of a channel, which requires understanding the effects of partial vegetation on the flow. Although many studies have been done on flows through uniform vegetation, this type of flow is unrealistic, as in natural floodplains, the vegetation in riparian zones is usually non-uniform. There is little study on the hydraulic characteristics of the flow with the co-existence of short and tall vegetation under either emergent or submerged conditions. In this paper, a novel experiment with rigid vegetation of two heights in one side of a channel was conducted to understand flow characteristics such as velocity profile, turbulence intensity, Reynolds stress, and discharge distribution. Experimental results revealed that the velocity is almost constant over the short vegetation height and increases sharply with the depth just above the short vegetation. Similarly, the Reynolds stress had little variation in the short vegetation layer, but started to increase rapidly from the top of the short vegetation to the water surface, which indicates the presence of strong mixing layer near the top of the short vegetation. Additionally, a strong shear layer existed between non-vegetated and vegetated zones, indicating the reduction effect of vegetation on the flow velocity. Furthermore, modifications are needed to properly calculate the hydraulic radius and Manning's coefficient for the flow with double-layered vegetation.
16. Lean construction application: A case study in Suzhou, China

Author:Xing, W;Hao, J;Wu, D;Qian, L;Sikora, KS


Abstract:Chinese Architecture, Engineering, Construction (AEC) industry is under the reform resulting from the large amount of waste production, huge energy consumption and severe environmental pollution. Aiming to maximize the project value while reducing the waste and cost, lean thinking is referred from manufacturing industry to construction since two industries have several similarities. This paper reviewed the change of lean thinking from production to construction, the differences between traditional and lean construction (LC), and the current situation of Chinese LC situation. Besides, a case study was assessed to examine how the LC management works in a practical project in China. Through the research, project schedule is divided into several hundred sub-items to assist the site supervisors to manage the construction progress. In addition, utilizing prefabrication parts and digital technology are two effective approaches to conduct the LC in the project.
17. VR-based teaching and learning tool for building design and construciton

Author:Zhang, C. ; Chen, And B.

Source:EUCEET 2018 - 4th International Conference on Civil Engineering Education Challenges for the Third Millennium,2018,Vol.

Abstract:A Virtual Reality (VR) based teaching and learning tool is proposed in the present paper. A virtual 3D environment is built for students to conceive their design ideas, plan the layout, design the structure, construct the products (buildings, communities, infrastructures, etc.), and to directly interact with the products they designed. The aim of the research is to strengthen the learning-by-doing approach. The objectives are (1) to build a VR design environment for students to experience corresponding impact from different scenarios, which will help the student understand and investigate different design theories and schemes; (2) to build a VR construction environment for students to investigate how the building is built and what are the safety issues should be noted when visiting a construction site; and (3) to provide an collaborative environment for students in the Built Environment domain for better communication through a complete building project featuring active and experiential learning. Students with different majors in the cluster can work together in a design project using the VR platform so as to enable collaboration work, which is a common working situation in reality. A game was developed to guide the students to explore a virtual construction site by answering technical questions and carrying on tasks resolving safety hazards on site. Unity is used as the game engine to develop the package. VR software package, VIVE, is used to realize the interaction between the virtual environment and the user interactively and immersively. Students from the Civil Engineering were invited to play the game and give feedbacks using a questionnaire. Positive comments were given by the students showing that they were very interested in playing such a technical game. Most of the students were willing to spend more time in finding answers after playing that game. In this way, the benefits of the research could be (1) Enhancing the understanding of conceptual design ideas and how to make better designs in urban planning, architecture, and civil engineering domains; (2) Better accessibility to more realistic structural products in a large scale; and (3) Improving professional skills such as teamwork and communication in the VR-aided learning-by-doing process. © 2018 EUCEET 2018 - 4th International Conference on Civil Engineering Education Challenges for the Third Millennium. All rights reserved.

Author:Guanlin YE;Yonglin XIONG;Yuanfeng BAO;Bin YE;Feng ZHANG

Source:The Fifteenth East Asia-Pacific Conference on Structural Engineering & Construction (2017第十五届东亚-太平洋结构工程及施工国际会议)(EASEC-15)论文集,2017,Vol.

Abstract:  In considering boundary value problems related to soil-structure interaction, both the structure and the soil are involved in the calculation.It is important to consider properly the geometric and material nonlinearities of both the structures and the soils.In this study, a rigorous numerical scheme for space beam element that can properly take the geometric and the material nonlinearities of structures into consideration was introduced and embedded into the DBLEAVES (Ye, 2011).Soil-water coupled dynamic analyses were conducted on a soil-group pile foundation-superstructure system to investigate the seismic behavior of an elevated bridge with a 12-pile foundation during a major earthquake.
19. Recent development of multi-purpose utility tunnels in China

Author:Luo, Y. ; Zhang, C. ; Hammad, A.

Source:Proceedings, Annual Conference - Canadian Society for Civil Engineering,2019,Vol.2019-June

Abstract:Repeated excavations of buried utilities cause road congestion and maintenance conflicts. Besides, the interference of buried utilities in limited underground spaces does not meet the requirement of sustainable urban underground development. Multi-purpose utility tunnels (MUTs) integrate all utilities together in one tunnel and can be accessed by humans. MUTs reduce the excavation needs and costs and avoid the traffic congestion caused by excavations. MUTs also provide easy access for inspection and maintenance of all types of utilities inside the tunnel. There are many MUTs in use in Europe and Japan, but the development of new tunnels in recent years is limited and lacks long-term planning. On the contrary, China is making a big progress in MUT planning and construction in recent years because the Chinese government is taking MUT construction as an important urban infrastructure development. The experience of MUT planning, construction and management in China can be very useful for other countries to examine the potential of MUTs as a sustainable option for future municipal asset rehabilitation projects. This paper first reviews the new development of MUTs including MUT history in China and the total planned and constructed lengths. Furthermore, several projects in major Chinese cities are reviewed including basic data on the length, cross-section, utilities housed, and cost analysis. It is concluded that although the initial cost of MUTs is high, they are sustainable and cost-effective infrastructures for underground utilities in the long term. It is hoped that this paper will encourage further research about the usage of MUTs. � 2019 Canadian Society for Civil Engineering. All rights reserved.
20. Prediction of Flow Velocity Profiles of Open-Channels with Submerged Vegetation

Author:Tang, Xiaonan


Abstract:For submerged vegetated flow, the vertical velocity profile can often be described by two layers, the vegetation layer in the lower region and the surface layer in the upper non-vegetated region. In this paper, based on the momentum equation of flow with an assumption of turbulent eddy viscosity being a linear relationship with the local velocity, a two-layer velocity profile for flow in an open-channel with rigid submerged vegetation is proposed. The proposed model was tested against several datasets widely used previously in literature. Our studies show that the model can predict the velocity profiles well for all datasets. In the test, it was found that the mixing length scale of eddies () is well related with both vegetation height (h) and flow depth of surface layer (i.e. height of non-vegetation layer, H-h). Close examination of the length scale  in the proposed model showed that when /h = 0.03(H/h-1)1/2, the model can predict velocity profiles well for all the datasets used. The datasets used include various submergence [flow depth (H)/vegetation height (h) =1.25 ~ 3.33], different vegetation densities of a =1.1 ~ 18.5 m-1 (a defined as the frontal area of the vegetation per unit volume) and bed slopes (So = 4.0x10-4 ~4.0x10-3).
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