Conference Presentations by Nhat Minh Ho
CIGOS 2019, Innovation for Sustainable Infrastructure, Proceedings of the 5th International Conference on Geotechnics, Civil Engineering Works and Structures, 2020
The modern-day popularity of tilt-up construction, shear walls and concrete cores in multi-storey... more The modern-day popularity of tilt-up construction, shear walls and concrete cores in multi-storey buildings means that the construction of concrete walls with various boundary conditions and higher slenderness ratios, along with the presence of openings, has become common. The design of such elements under eccentric axial loads, however, could be outside the restrictions of current major design codes such as the Eurocode 2 (EC2-2004), the American Concrete Institute Code (ACI318-2014) and the Australian Concrete Standard (AS3600-2018). There have been many experimental and numerical studies on the behaviour of both one-way action walls and two-way action walls supported on four sides, with and without openings in the range of high slenderness ratios (up to 50). Efforts have also been made to develop design models capable of predicting the axial load capacity of such walls. However, research into the behaviour of two-way action walls supported on three sides (TW3S walls) is still relatively unexplored and further studies in this area are needed. Recent research has demonstrated that a rigid-plastic approach could be used to describe the behaviour of TW3S walls with and without openings. Although predictions obtained using the rigid-plastic approach showed reasonably good agreement with experimental test data, the scope of the analysis approach is considered limited. In this study, a validated finite element method, using the ABAQUS program, was employed to improve the rigid-plastic model, covering a broader spectrum of designs for axially-loaded TW3S walls. The reliability of the modified model was confirmed through comparisons with the available test data.
EASEC-14, 2016
Due to recent popularity of tilt-up construction and concrete cores in tall buildings, reinforced... more Due to recent popularity of tilt-up construction and concrete cores in tall buildings, reinforced concrete (RC) walls are now considered just as important structural element as beams, slabs and columns. The Australian Concrete Standard, AS3600-09 for the simplified design of axially loaded walls allows for increased capacity due to side restraints compared with previous code of AS3600-01 and current American Concrete Institute Code, ACI318-14. Nevertheless, all of these codes do not significantly account for openings such as doors or windows. In view of the limitation, it is necessary to widen the scope of the methods and rectify the inadequacies which exist in these major national design codes. This paper presents shortcomings of the AS3600-09 and also reviews existing experimental tests by previous researches. It includes wall with various opening configurations and support conditions subjected to eccentric axial loading. Using the results obtained from previous experimental studies, a simple design method for various opening walls with support conditions has been derived. Comparisons are then made with the otheravailable empirical equations to highlight its accuracy, reliability and outstanding performance.
The 6th International Conference on Construction Engineering and Project Management (ICCEPM 2015), 2015
The incorporation of sustainability principles into the structural engineering design of building... more The incorporation of sustainability principles into the structural engineering design of buildings is increasingly important. Historically the focus of improvements to the environmental performance of structures has been operational energy considerations. Current research has highlighted the requirement for changing the approach by increasing the consideration of embodied energy in structures. This research was conducted to build on previous research by the authors in quantifying the contribution of column optimization to the embodied energy performance of concrete framed buildings. Ultimately, the authors intend to develop mechanisms through which sustainable design can be quantified, enabling alleviation prior to construction. Columns are a key structural element to consider as part of this development process. The outcomes of this assessment reinforced previous findings, observing that reduced structural weight as a result of other sustainable design measures carries manifold benefits include column design savings. Through the quantification of the embodied energy outcomes during this research phase, the columns were shown to contribute up to 19.71% of the total embodied energy of the structural system dependent upon construction technique used.
Papers by Nhat Minh Ho
Innovative Infrastructure Solutions
Determination of the early-age compressive strength of concrete is essential for quality assuranc... more Determination of the early-age compressive strength of concrete is essential for quality assurance, safety, and economy of construction projects. Due to manual operation on construction site, conventional maturity meters are not efficient for live monitoring of the early-age concrete strength. Higher levels of automated and computerised improvements have been made possible by recent developments in wireless communications, sensor technologies, and data processing methods across the construction industry. For real-time monitoring of the early-stage concrete strength, the current study presents an innovative Internet of Things (IoT)-enabled system developed by concrete data sensors (CDS), an Australian-owned private business. The CDS sensor system (the system) communicates with temperature sensors via long-range wide-area network and is linked to a cloud-based platform for data storage. The suggested system’s effectiveness was assessed using three concrete mixtures and developed matur...
Numerical modeling techniques and investigation into the flexural behavior of two‐way posttensioned concrete slabs with profiled steel sheeting
Structural Concrete
Monitoring of in-place strength in concrete structures using maturity method – An overview
Structures
Lecture Notes in Civil Engineering, 2019
The modern-day popularity of tilt-up construction, shear walls and concrete cores in multi-storey... more The modern-day popularity of tilt-up construction, shear walls and concrete cores in multi-storey buildings means that the construction of concrete walls with various boundary conditions and higher slenderness ratios, along with the presence of openings, has become common. The design of such elements under eccentric axial loads, however, could be outside the restrictions of current major design codes such as the Eurocode 2 (EC2-2004), the American Concrete Institute Code (ACI318-2014) and the Australian Concrete Standard (AS3600-2018). There have been many experimental and numerical studies on the behaviour of both one-way action walls and two-way action walls supported on four sides, with and without openings in the range of high slenderness ratios (up to 50). Efforts have also been made to develop design models capable of predicting the axial load capacity of such walls. However, research into the behaviour of two-way action walls supported on three sides (TW3S walls) is still relatively unexplored and further studies in this area are needed. Recent research has demonstrated that a rigid-plastic approach could be used to describe the behaviour of TW3S walls with and without openings. Although predictions obtained using the rigid-plastic approach showed reasonably good agreement with experimental test data, the scope of the analysis approach is considered limited. In this study, a validated finite element method, using the ABAQUS program, was employed to improve the rigid-plastic model, covering a broader spectrum of designs for axially-loaded TW3S walls. The reliability of the modified model was confirmed through comparisons with the available test data.
Experimental and Theoretical Studies on Three-side Restrained Reinforced Concrete Walls
Cast in situ or precast reinforced concrete (RC) walls are commonly used in multistorey buildings... more Cast in situ or precast reinforced concrete (RC) walls are commonly used in multistorey buildings to withstand gravitational and lateral loadings. Walls restrained along the top and bottom edges by floors, with free vertical edges, subjected to in-plane axial loads behave in one-way action (OW). Axially-loaded walls can also behave in two-way action with lateral support on three sides (TW3S) or four sides (TW4S), formed by floors and intersecting walls, when they are combined to form an isolated box, a bundled box, a coupled core, or a geometric, U-, T- or L-shape. In many circumstances, walls are pierced with openings because of architectural requirements or functional modifications of the structures. However, these openings are a source of weakness and can size-dependently reduce the stiffness and load-bearing capacity of the structure. RC walls subjected to eccentric axial loads can be designed using simplified design methods, provided in major codes of practice, which include, i...
Design assisted by testing applied to the determination of the design resistance of RC walls restrained on three sides
Axially loaded reinforced concrete walls can be constructed with various support conditions. Wall... more Axially loaded reinforced concrete walls can be constructed with various support conditions. Walls can be designed using simplified design methods given in codes such as the Australian Concrete Standard (AS3600-09), the Eurocode 2 (EC2-04) and the American Concrete Institute Code (ACI318-14). There is little research published on the behaviour of three-side restrained (TW3S) walls. As such, an experimental programme was undertaken on three TW3S walls. The dimensions of the walls were selected by incorporating the provision for varying values of slenderness ratio and aspect ratio. All panels were subjected to eccentric axial loadings and tested to failure. The design equations specified in the aforementioned codes were found to be inadequate in predicting the failure load for TW3S walls of high slenderness ratios. In addition, an instability analysis incorporated into a computer program called WASTABT, to establish the behaviour of TW3S walls, is also presented. The outputs from the ...
Simple Design Method for Opening Wall with Various Support Conditions
Due to recent popularity of tilt-up construction and concrete cores in tall buildings, reinforced... more Due to recent popularity of tilt-up construction and concrete cores in tall buildings, reinforced concrete (RC) walls are now considered just as important structural element as beams, slabs and columns. The Australian Concrete Standard, AS3600-09 for the simplified design of axially loaded walls allows for increased capacity due to side restraints compared with previous code of AS3600-01 and current American Concrete Institute Code, ACI318-14. Nevertheless, all of these codes do not significantly account for openings such as doors or windows. In view of the limitation, it is necessary to widen the scope of the methods and rectify the inadequacies which exist in these major national design codes. This paper presents shortcomings of the AS3600-09 and also reviews existing experimental tests by previous researches. It includes wall with various opening configurations and support conditions subjected to eccentric axial loading. Using the results obtained from previous experimental studi...
Structures, 2020
Currently, the empirical wall design equations given in major codes of practices either offer no ... more Currently, the empirical wall design equations given in major codes of practices either offer no guidelines or provide overly conservative predictions of the ultimate axial strength of concrete walls with openings restrained on three sides (TW3S walls with openings). In view of the significant shortcomings, an appropriate design equation is required for such walls. This paper presents a numerical investigation on the behaviour of TW3S walls with openings under eccentric axial loading. A finite element model using the ABAQUS software was employed to undertake parametric studies examining the influence of opening parameters, which consisted of configuration and location, on the axial load capacity of TW3S walls. In total, 101 models were developed and analysed. Having established the relationships between the opening parameters and the ultimate load capacity of TW3S walls, a more encompassing design 2 equation was derived. The reliability of the proposed equation was ascertained through comparisons with available test data.
The contribution of column optimization on the embodied energy performance of concrete framed buildings
The incorporation of sustainability principles into the structural engineering design of building... more The incorporation of sustainability principles into the structural engineering design of buildings is increasingly important. Historically the focus of improvements to the environmental performance of structures has been operational energy considerations. Current research has highlighted the requirement for changing the approach by increasing the consideration of embodied energy in structures. This research was conducted to build on previous research by the authors in quantifying the contribution of column optimization to the embodied energy performance of concrete framed buildings. Ultimately, the authors intend to develop mechanisms through which sustainable design can be quantified, enabling alleviation prior to construction. Columns are a key structural element to consider as part of this development process. The outcomes of this assessment reinforced previous findings, observing that reduced structural weight as a result of other sustainable design measures carries manifold benefits include column design savings. Through the quantification of the embodied energy outcomes during this research phase, the columns were shown to contribute up to 19.71% of the total embodied energy of the structural system dependent upon construction technique used.
Axially loaded three-side restrained reinforced concrete walls: A comparative study
Structural Concrete, 2019
This paper presents experimental and numerical investigations on the behaviour of axiallyloaded c... more This paper presents experimental and numerical investigations on the behaviour of axiallyloaded concrete walls restrained on three sides (TW3S walls). Particular emphasis was given to the influences of varying the slenderness ratio, aspect ratio, concrete strength, and eccentricity on the ultimate axial strength of TW3S walls. Because of the overly conservative nature of the code design equations and the scarcity of other available models for estimating the ultimate axial strength of TW3S walls, a more encompassing design equation has been developed. Comparisons with the test data of the current and previous studies confirmed that the proposed equation is satisfactory and reliable.
The Structural Design of Tall and Special Buildings, 2017
Axially loaded reinforced concrete (RC) walls can be designed using simplified design methods giv... more Axially loaded reinforced concrete (RC) walls can be designed using simplified design methods given in codes such as the Australian Concrete Standard (AS3600-09) and the American Concrete Institute Code (ACI318-14). The ACI318-14 equation is intended for load bearing walls supported at top and bottom only. The AS3600-09 includes effective height factors to distinguish the effect of various support conditions, and also allows for higher concrete strengths and new guidelines not provided in the previous release, AS3600-01. However, these practical equations are based on empirical models and their scope of application is still limited. Recent research has been undertaken on the applicability of more reliable and accurate wall design methods. This paper initially presents a derived numerical technique incorporated in a computer program (WASTABT), to implement the iterative analysis for concrete walls with various support conditions. The outputs from the WASTABT program are verified using the results obtained from previous experimental results. A parametric study is then conducted using the verified computer-based numerical technique to analyse axially loaded RC panels. The study focuses on the effect of varying panel properties such as wall dimensions, concrete strengths, eccentricities and reinforcement ratios, along with varying support conditions.
Journal of Steel Structures & Construction, 2017
Modular construction methods have been adapted globally for the past few decades and are becoming... more Modular construction methods have been adapted globally for the past few decades and are becoming more common due to their ease of use and flexibility. Structural connections between modules are required for integrity and robustness but details vary depending on the form of the module and the particular application. The behaviour of connections in analysis and design of modular buildings should particularly be taken into account in detail because of their effects on the distribution of internal forces and on structural deformations. The purpose of this paper is to present and analyse the behaviours of an innovative steel bracket connection. Experiments, including shear loading and simply supported tests, were carried out to establish directly the ultimate resistance as well as failure modes of the connections. The finite element software, Strand7, was subsequently utilised to produce models for comparison with test results. A parametric study has been carried out to investigate the effects of varying bolthole dimension and bolthole spacing on the structural behaviours of the steel bracket connection using linear analysis. The model presented in this paper was formed as a baseline for future in-depth investigations to ensure design optimisation of the steel bracket connection.
Experimental and numerical investigations of axially loaded RC walls restrained on three sides
The Structural Design of Tall and Special Buildings
The Structural Design of Tall and Special Buildings, 2017
Axially loaded reinforced concrete (RC) walls can be designed using simplified design methods giv... more Axially loaded reinforced concrete (RC) walls can be designed using simplified design methods given in codes such as the Australian Concrete Standard (AS3600-09) and the American Concrete Institute Code (ACI318-14). The ACI318-14 equation is intended for load bearing walls supported at top and bottom only. The AS3600-09 includes effective height factors to distinguish the effect of various support conditions, and also allows for higher concrete strengths and new guidelines not provided in the previous release, AS3600-01. However, these practical equations are based on empirical models and their scope of application is still limited. Recent research has been undertaken on the applicability of more reliable and accurate wall design methods. This paper initially presents a derived numerical technique incorporated in a computer program (WASTABT), to implement the iterative analysis for concrete walls with various support conditions. The outputs from the WASTABT program are verified using the results obtained from previous experimental results. A parametric study is then conducted using the verified computer-based numerical technique to analyse axially loaded RC panels. The study focuses on the effect of varying panel properties such as wall dimensions, concrete strengths, eccentricities and reinforcement ratios, along with varying support conditions.
Structural Concrete, 2019
This paper presents experimental and numerical investigations on the behavior of axially-loaded c... more This paper presents experimental and numerical investigations on the behavior of axially-loaded concrete walls restrained on three sides (TW3S walls). Particular emphasis was given to the influences of varying the slenderness ratio, aspect ratio, concrete strength, and eccentricity on the ultimate axial strength of TW3S walls. Because of the overly conservative nature of the code design equations and the scarcity of other available models for estimating the ultimate axial strength of TW3S walls, a more encompassing design equation has been developed. Comparisons with the test data of the current and previous studies confirmed that the proposed equation is satisfactory and reliable.
The Structural Design of Tall and Special Buildings, 2017
Axially loaded reinforced concrete (RC) walls in tilt-up structures can be supported top and bott... more Axially loaded reinforced concrete (RC) walls in tilt-up structures can be supported top and bottom only by floors or roof structures. However, RC walls are often combined to form I-, C-, T-and L-shapes to make efficient use of the building area in multi-storey buildings. With these configurations, walls may also be laterally supported on either or both sides by interconnecting walls. While many researchers have investigated the behaviours of RC walls, either in one-way action or two-way action supported on four sides with and without openings, limited research has been conducted on two-way action walls supported on three sides (TW3S). As such, this paper experimentally and numerically investigates the behaviour of TW3S walls. Details of the twelve half-scale walls tested, including experimental setup, failure loads, crack patterns and load-deflection characteristics, are reported. In addition, the Finite Element Method using ABAQUS software for investigating the behaviour of TW3S walls is described in detail. Finally, due to the conservative nature of code design equations and there being limited available methods for predicting the ultimate load of TW3S walls with openings, a rigid-plastic approach has been proposed in this study to evaluate the failure load of TW3S walls.
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Conference Presentations by Nhat Minh Ho
Papers by Nhat Minh Ho