R.K.L. Su

• The University of Hong Kong

This paper investigates the service life modelling of Hong Kong buildings subject to carbonation-induced corrosion. The provisions on the design parameters of carbonation-induced corrosion in Hong Kong standards at different periods are summarised. Data from field investigations concerning carbonation-induced corrosion are presented, including in r...

The high level partial replacement of ordinary Portland cement (OPC) with ground granulated blast‐furnace slag (GGBS) is being increasingly employed due to the heavy environmental burden of construction work. This study experimentally investigates the interfacial shear strength of concrete construction joints with high GGBS replacement levels. The...

This research proposes a novel deep breathing analogy (DBA) accelerated carbonation process. Inspired by the breathing mechanism of human lungs, the DBA method involves injecting pure CO2 into a reaction chamber at a specific pressure (inspiration) and subsequently evacuating the gas from the chamber to a negative pressure (exhalation). This proces...

A novel retrofit method for reinforced concrete (RC) columns using a direct fastening steel jacket has been newly developed. This novel retrofit method features a simple and quick retrofit procedure, whereby high-strength fasteners are actuated and driven through to connect steel angles, steel plates and the concrete surface surrounding the column....

The vibration responses of tall flexible tool (or equipment) platforms subjected to floor excitations at the platform base are considered more crucial than those of the short ones. This study examined the microvibration control performance of the proposed active piezoelectric mass damper (APMD) or driver for tall platforms subjected to internal aut...

Alkali-activated materials have great potential in reducing CO2 emissions in cement production industry. This study aims to investigate the corrosion propagation performance of alkali-activated slag mortars with various pulverized fuel ash (PFA) and metakaolin (MK) replacements subject to chloride-induced corrosion. The corrosion propagation perfor...

Foam concrete is a promising material in building and construction applications, providing such outstanding properties as high specific strength, excellent thermal insulation, and effective acoustic absorption in human-inhabited buildings. However, because the porosity and permeable water absorption properties of foam concrete are significantly hig...

Chloride-induced corrosion poses extreme vulnerabilities to the strength degradation and delamination of reinforced concrete structures in the oceanic environment. For this reason, the self-prestressing effect produced from the synergy of the combined addition of expansive agent (EA) and steel fibre (SF) into the concrete is suggested to enhance th...

This study aims to examine the seismic performance of non-seismically designed shear wall with moderate shear span-to-length ratios (SLR) under relatively high axial loads. Four wall specimens with varying parameters, such as shear-to-flexure strength ratio, SLR, and axial load ratio (ALR) are fabricated and tested under cyclic loads. The experimen...

Assessment of the fire-induced spalling of high-strength concrete in concrete structures requires knowledge of the tensile strength of concrete at an elevated temperature. However, previous research has mainly focused on determining residual tensile strength, measured at the post-fire stage after cooling the specimens to ambient temperature. Howeve...

Fiber reinforced polymer (FRP) bar reinforced ultra-high-performance concrete (UHPC) members have attracted wide interest due to their excellent durability and mechanical properties. Determining bond strength is of great importance to the design of FRP bar reinforced UHPC members. This study investigates the effects of bar type, concrete type and r...

Strut-and-tie modelling has proved a very useful method in the analysis and design of non-flexural components of reinforced concrete members. Examples of design codes encompassing the strut-and-tie model (STM) provisions include Eurocode 2 (EC2), the fib Model Code 2010 (MC2010), the Canadian Standard (CSA A23.3-04), the American bridge design spec...

The use of supplementary cementitious materials (SCMs) has led to a decrease in the corrosion initiation of carbonated reinforced concrete (RC). Hence, studies on the corrosion propagation of carbonated SCM concrete are becoming important but remain limited. In this study, ordinary Portland cement (OPC) was partially replaced with pulverized fly as...

Fragility analysis is an effective tool used to assess the seismic risk of high‐rise buildings. During the process of fragility analysis, determining the engineering demand parameters (EDPs) corresponding to different damage states is of great importance as they directly influence the fragility results. However, for buildings with transfer structur...

This study investigates the corrosion rate measurement of reinforcing steel under chloride-induced macrocell corrosion in reinforced concrete (RC). The corrosion rates of RC columns with different cover thicknesses and chloride concentrations were evaluated using different techniques and cathode over anode ratios. The applicability of the Stern-Gea...

A State-of-the-Art Guide for Post-Installed Reinforcement provides comprehensive coverage on installation, design, and assessment guidelines for post-installed reinforcements, a unique technology used very commonly in the construction industry. Previously published in Hong Kong, this Malaysian edition includes new EOTA technical reports and Europea...

Building inspection and maintenance are becoming increasingly essential means by which to consider the deterioration problems of old, reinforced concrete (RC) buildings. While such inspection work can be conducted with the aid of computer vision-based technology, this technology remains challenged, since real-world structural defects and environmen...

This study explores the micro vibrations in long span floors induced by internal moving vehicles or automated guided vehicles (AGVs) in high technology fabrication factories (or fabs) by using a bivariate fragility assessment model that considers both the vehicle weight and moving speed. Dynamic time history analyses of an equivalent sub-structural...

Strut-and-tie model (STM) is a powerful tool to physically define the load transfer mechanism in reinforced concrete and has been widely used in reinforced concrete design for disturbed regions featuring non-flexural strain sections. In this paper, a unified concept of STM is extended to contemporary construction methods for concrete-to-concrete co...

Cover cracking caused by rebar corrosion is one of the most predominant deterioration problems of reinforced concrete structures. Cracking types include three main modes: cover spalling, cover delamination and corner cracking. However, despite being one of the most common cracking problems, corner cracking is seldom studied by way of experimental t...

Curved steel–concrete composite girders are regularly adopted for use in ramp bridges in urban overpasses. As such, it is important that the lateral overturning stability of girders supported by single-column piers is analyzed. In order to comprehensively evaluate the lateral overturning mechanism of girders, this paper carries out a full-range non...

Curved steel–concrete composite box beams are widely used in urban overpasses and ramp bridges as they are light in weight, have large spanning ability and high torsional rigidity. One-dimensional models are generally used to analyze bridge performance due to their calculation and numerical efficiencies. An incremental step-by-step method based on...

Cover delamination caused by the corrosion of multiple rebars is one of the most predominant deterioration problems of reinforced concrete (RC) structures. To date, there has been little experimental research on cover delamination, and in the few studies that have focused on this issue, different types of failure, such as cracking, spalling and del...

This paper investigates the effects of rebar geometry, namely the rib and diameter of rebar, on the steel–concrete interface (SCI) and corrosion initiation of reinforcing steel. Cutting-induced damage on the SCI is also studied using various W/C ratios, cutting wheels and rebar diameters. Interfacial porosity and the distribution of chloride ions a...

The expansion of rust is often inhibited by the compression from concrete and the effects of the diffusion of rust, which obscure the actual amount of damage caused by the corrosion of the reinforcements. In this work, the relationship between the actual expansion and deposition of rust with a certain amount of corrosion is quantified by directly m...

This paper investigates the fracture characteristics of a Yoffe conductive crack moving along the interface of piezoelectric (PE)/piezomagnetic (PM) bimaterials. By assuming that the tangential electric- and magnetic-fields along the crack surface are zero and that the speed of the moving crack is lower than the minimum shear wave speed of the bima...

Reinforced concrete (RC) columns can be strengthened by direct fastening of steel plates around a column, forming composite actions. This method can increase both the total load bearing area and the concrete confinement stress. To predict the axial load resistance of strengthened RC columns, the equivalent passive confinement stress of the stirrups...

For non-seismically designed columns with insufficient strength and flexural stiffness, intense inter-story drift can be incurred during a strong earthquake event, potentially leading to the collapse of the entire building. Existing strengthening methods mainly focus on enhancing axial or flexural strength but not the flexural stiffness of columns....

Curved steel–concrete composite girders have been widely used in curved bridges of overpasses in urban areas as they have a lower self-weight and require less construction time. These curved beams have been often numerically simulated with the use of a more elaborate three-dimensional (3D) finite element (FE) model to predict their mechanical behav...

General consensus in the literature is that the fracturing behavior of nuclear graphite shows a certain degree of nonlinearity due to the presence of a fracture process zone (FPZ) ahead of the crack tip. Thus, it is necessary to take the influence of the FPZ into account when investigating the fracture properties of nuclear graphite. Besides, the e...

Carbon textile reinforced mortar (CTRM) is an advanced composite material that has excellent fire resistance, high strength and ductility, and good energy dissipation ability. Nevertheless, its full potential has not been fully investigated in the literature. In this paper, the flexural behaviour of preloaded reinforced concrete (RC) beams strength...

Guide for Design, Installation, and Assessment of Post-installed Reinforcements sets out the installation, design, and assessment guidelines for post-installed reinforcements and fills a much-needed gap in the literature. The technology of post-installed reinforcement is growing increasingly important since reinforcing bars are being used frequentl...

Despite the widespread application of digital image correlation (DIC) method in concrete structures, there is no standard procedure to systematically optimising the parameters of DIC. A framework is thus proposed in this paper to optimise two-dimensional (2D) measurements with DIC at different orders of accuracy required in concrete structure model...

The applicability of the polarization resistance method to microcell and macrocell corrosion (MMC) has been often ignored. To address this research gap, this study investigates corrosion rate measurement by using the polarization resistance method on MMC of reinforced concrete. A modified Stern-Geary equation for MMC is proposed to consider the eff...

The large uncertainty of the value of the deformation modulus of rust in the literature and the granular property of rust make it difficult to correctly simulate the interaction between the corroded reinforcement and concrete, including rust expansion and bond slip behavior. To fill the gap, this study thereby quantifies the deformation modulus of...

Reinforced concrete (RC) columns designed in accordance with older design codes that do not incorporate seismic resistance are prone to brittle failure. These defective columns may lead to the development of a non-ductile column sway mechanism during a strong earthquake. This failure process can be however remedied by strengthening the defective co...

Corrosion-caused cover cracking can lead to the serious deterioration of reinforced concrete (RC) structures. However, only a few experimental studies in the literature have examined the entire cracking process of specimens with a realistic configuration that consists of both the concrete cover and concrete core. Herein, the mechanism and process o...

The heated bar effect on the corrosion rate, corrosion potential and resistivity of partially carbonated concrete is discussed in this paper. The potential use of pulverized fuel ash (PFA) as a substitute for cement to mitigate the heated bar effect is explored. It is found that the heated bar effect can lead to an increase in the corrosion level....

Post-installed reinforcement (PIR) helps facilitate retrofitting works, mitigate misplaced reinforcement problems, as well as support newly cast concrete members such as modular integrated construction. However, it has not been holistically addressed in major international reinforced concrete (RC) design codes. Nonetheless, based on established des...

Reinforced concrete (RC) shear walls are widely utilized to resist lateral and gravity loads in modern building designs. The adjacent wall piers are usually connected to the coupling beams. Severe earthquake and wind loads challenge the seismic and shear resistance of conventional reinforced concrete (RC) coupling beams respectively. Their shear an...

Nonseismically detailed reinforced concrete (RC) shear walls adjacent to transfer structure in tall buildings are found to have short shear spans and designed to hold considerable axial load. In a previous paper, a Modified Mohr's Axial Capacity Model was developed by the authors to estimate the axial collapse of these RC walls in seismic events, w...

The failure of concrete covers due to corrosion of the corner rebars is different from that of the interior rebars. To date, there is no specific analytical model for simulating corner cracking in the literature. In response, this paper proposes a novel analytical model, which considers both the non-uniform distribution of rust and the boundary con...

Reinforced concrete (RC) columns are crucial structural members that sustain vertical loads. Their strength may deteriorate due to fire, corrosion of the reinforcements or design errors. In response, a new strengthening method that uses a steel encasement to increase the axial capacity and ductility of RC columns is proposed in this paper. This met...

This paper presents an analogous method to predict the distribution of non-uniform corrosion on reinforcements in concrete by minimizing the Wasserstein distance. A comparison between the predicted and experimental results shows that the proposed method is capable of predicting distributions of non-uniform corrosion modeled by Gaussian functions. T...

Premature failure due to plate-end debonding or plate-end separation can take place in reinforced concrete (RC) beams with a bonded plate at soffit, which results from concentration of adhesive stresses at the plate ends. Many theoretical studies based on the Euler-Bernoulli beam theory for simply supported beams bonded with plates and subjected to...

Direct fastening is an effective method to quickly and easily connect two steel components. However, the behaviors of this kind of connection have been rarely studied and there is no direct reference to them in current design specifications. Therefore, it is now timely to investigate the properties and behavior of this type of connection. In this p...

Cover delamination failure caused by the corrosion of closely spaced rebars is commonly found in deteriorated reinforced concrete (RC) structures. However, analytical studies carried out on this failure mode of RC structures are rare. In response, this paper proposes a novel analytical model for cover delamination which takes into account the inter...

Post-installed reinforcement (PIR) bars helps to facilitate retrofitting works, mitigate misplaced reinforcement problems, as well as support newly casted additions. However, the use of PIR has not been addressed in the major reinforced concrete (RC) design codes worldwide. Recently, the European standards have introduced a beneficial coefficient o...

This paper reports an experimental and numerical study on the fracture properties of nuclear graphite NG-CT-01 produced in China. Three-point bending tests were performed on center-notch beams and electronic speckle pattern interferometry (ESPI) technique was employed to measure the full-field deformation of the beams. Besides, finite element analy...

In an attempt to promote the use of precast segmental bridge columns in regions of moderate to high seismicity, sliding planar joints have been adopted to relieve the adverse effects of seismic action. However, despite the ability to survive, the sliding segments often result in noticeable residual relative movements after an earthquake, which requ...

In an attempt to promote the use of precast segmental bridge columns in regions of moderate to high seismicity, sliding planar joints are adopted to relieve the adverse effects of seismic action. However, despite the ability to survive, the sliding segments often result in noticeable residual relative movements after an earthquake, which require co...

A novel elastic-body-rotation model is proposed to analyze the mechanism and the process of cover cracking and spalling caused by the non-uniform corrosion of widely spaced reinforcements. The width of the cover surface cracks, bulging of the concrete surface and maximum thickness of the corroded steel can be predicted by using the proposed model....

One-phase models of rebar corrosion have been widely used by practising engineers to predict the volume of rust and the time to cracking of the concrete cover, but the models have only considered the deformation of concrete and not the deformation of steel or the rust layer. Neglecting the deformation of the rust layer may result in inaccurate pred...

In order to study the size effect in concrete fracture, three-point bending tests are performed on five groups of geometrically similar concrete beams. The electronic speckle pattern interferometry (ESPI) technique is used to measure the full-field deformation of concrete beams. Crack opening displacement data, which is crucial for understanding cr...

Modular construction has been adopted as a new form of construction to enhance quality and productivity. However, most of the success stories of adopting modular systems are limited to low-rise buildings. This paper explores the feasibility of engineering modular integrated construction systems for high-rise buildings where wind action can be a maj...

This paper presents an experimental investigation on concrete-filled steel tubular beam-columns with octagonal cross-sections (OCFST) under cyclic lateral loading with or without axial load. A total of nine specimens with different parameters, including the axial load level (n) ranging from 0 to 0.5 and concrete compressive cylinder strength (fc′)...

A special class of short shear span RC shear wall exists in the form of a sub-structure at the base of slender walls in tall buildings, was found common in the low-to-moderate seismicity region. These non-seismically designed short shear span RC walls are highly stressed in axial load under gravity and lateral actions, and have limited deformabilit...

Off-site manufacture of ‘plug and play’ modules is fast gaining ground in the plant and housing sectors. Wei Pan, Ray Su, Yancheng Cai and Ben Young of The University of Hong Kong outline the engineering challenges of modular high-rises and suggest some solutions.

A special class of short shear span RC shear wall exists in the form of a sub-structure at the base of slender walls in tall buildings, was found common in the low-to-moderate seismicity region. These non-seismically designed short shear span RC walls are highly stressed in axial load under gravity and lateral actions, and have limited deformabilit...

Existing reinforced concrete (RC) beams with inadequate flexural capacity can be strengthened by bolting steel plates onto both sides of the face of beam. However, the effectiveness of these bolted side-plated (BSP) beams is affected by the mechanical slipping of bolts which is known as the partial interaction of the steel plates and the RC beam. T...

The unified method for addressing the propagation of subsonic and transonic cracks along the interfaces of anisotropic bimaterials in Shen and Nishioka (2000) is applied in this paper for the plain strain problem of subsonic and transonic crack propagation along the interfaces of anisotropic magnetoelectroelastic (MEE) bimaterials. Using a modified...

A special class of RC shear wall is identified with short shear span, attributed to the high coupling degree in the elastic design of tall buildings located in low-to-moderate seismicity regions. The short shear span characteristic precludes plastic hinge formation and increase the susceptibility of shear failure during seismic events. It is noted...

Reinforced concrete (RC) columns, as the primary load-bearing structural components in buildings, may need to be strengthened due to material deteriorations, changes in usage, new building codes or new design requirements. The use of post compressed plates (PCP) to strengthen existing RC columns has been proven experimentally and practically to be...

The in-situ Young's modulus of rust is an important parameter in corrosion analyses. In this paper, the in-situ Young's modulus of rust in reinforced concrete is determined by a displacement-based inverse analysis method. The full field displacements of the surface of concrete in an accelerated corrosion test are first monitored by digital image co...

In this paper, the use of incremental displacement collocation method (IDCM) for the evaluation of the tension softening curve of quasi-brittle materials is presented. By varying the residual tensile stress on the tension softening curve (TSC) for each loading step, the measured displacements are matched with the computed displacements at selected...

In this paper, a new solution method is proposed to solve the one-dimensional analytical model of composite beams which is able to simulate the effects of interface slippage, and shear-lag and time-dependent effects. This method involves a solution of space and time variables. To enhance the accuracy of the solution, a space-exact analytical soluti...

Reinforced concrete (RC) shear walls in tall buildings are found to have a short shear span, particularly in high-degree coupled walls supported on transfer structures in low-to-moderate seismic regions. These non-seismically detailed walls in existing buildings are exposed to a high risk of failing in shear or compression before plastic hinges are...

Many existing deep reinforced concrete coupling beams that have low span-to-depth ratios are not desirable for seismic design due to their potential brittle failure with limited ductility and deformability. Previous experimental and numerical studies have demonstrated that the laterally restrained steel plate retrofitting method could effectively e...

Three-point bending tests are performed on center-notched graphite beams to study the fracture properties of IG11 graphite. Electronic speckle pattern interferometry (ESPI) is used to measure the full-field deformation of the graphite beams. A clip gauge is used to measure the crack mouth opening displacement (CMOD) of the beams, which validates th...

In order to study crack evolution in concrete, Electronic Speckle Pattern Interferometry (ESPI) technique was applied to measure full-field displacement of concrete beam subjected to three-point bending. Basic principles of ESPI technique were introduced. Mid-span deflection and crack mouth opening displacement were measured by linear variable diff...

The plane-strain problem of a moving crack at the interface of two dissimilar magnetoelectroelastic (MEE) materials is investigated. Assuming that the crack moves at a constant speed in the subsonic regime, a fracture analysis of a finite crack under concentrated loading imposed onto the crack face is first carried out. By applying magnetoelectric...

The performance of bolted side-plated (BSP) beams is affected by the degree of transverse partial interaction, which is a result of the interfacial slip caused by transverse shear transfer between the bolted steel plates and the reinforced concrete beams. However, explicit formulae for the transverse shear transfer profile have yet to be derived. I...

In this paper, the concrete cover tensile (CCT) capacity of cracked concrete caused by reinforcement corrosion is investigated. A newly developed double-cylinder model with the consideration of concrete confinement effects is used to evaluate the critical expansive pressure of the corrosion products necessary to cause unstable cover crack propagati...

With high resolution, electronic speckle pattern interferometry (ESPI) technique can be useful in measuring full-filed deformation of laboratory specimens. In this study, ESPI was applied to measure the full-field displacements of mortar beam subjected to three-point bend. Load-displacement curves measured by ESPI were compared to that measured by...

The seismic performance of steel reinforced engineered cementitious composite (RECC) short columns was investigated in this study. RECC columns with various shear span-to-depth ratios, axial load levels and transverse reinforcement ratios, together with one control reinforced concrete (RC) short column, were tested under the combined action of cons...

Design spectrum (DS) models in major codes of practice for structural design of buildings typically stipulate empirical site factors for each of the five, or six, site classes. Although the phenomenon of resonant like amplification behaviour of the structure caused by multiple wave reflections is well known, the potentials for such periodic amplifi...

This paper describes a comprehensive assessment of the seismic shear capacity of rectangular squat reinforced concrete walls through collection of up-to-date experimental database results. The theoretical shear capacity of wall specimens are first evaluated by axial-moment interaction curve in order to categorise the walls into shear, flexural-shea...

This paper describes a comprehensive assessment of the ultimate drift capacity of rectangular squat reinforced concrete (RC) walls through collection of up-to-date experimental database. Axial-moment curves are used to categorise the walls into shear or flexural failure modes. Important parameters contributing to drift, i.e. shear span to depth rat...

Existing deep reinforced concrete (RC) coupling beams with low shear span ratios and conventionally reinforced shear stirrups tend to fail in a brittle manner with limited ductility and deformability under reversed cyclic loading. Previous studies have developed a new retrofitting method with an unstiffened laterally restrained steel plate (LRSP) f...

In this paper, the extended finite element method (X-FEM) is employed to present a static fracture analysis of two-dimensional interfacial crack problems in linear magnetoelectroelastic (MEE) bimaterials. Magnetoelectrically impermeable crack-face boundary conditions are adopted and the multi-field coupled effect in MEE bodies is considered. In ord...