Hyo Eun Joo

• Doctor of Engineering
• Research Associate at The University of Tokyo

The impact of anisotropic cracking on concrete mechanically degraded by alkali–silica reaction (ASR) under multi-axial restraint conditions was quantitatively explored. An experimental framework was established to observe and correlate the expansion, compressive behaviour and crack patterns from different directions across specimens under free expa...

Quantitative correlations between mechanical degradation, expansion, and crack size distribution have not been identified in previous research on concrete degradation caused by alkali-silica reaction (ASR), limiting the accuracy of numerical modeling for ASR-induced damage. To fill this gap, this study introduces an experimental framework to concur...

Synopsis: In current ACI 318 code, crack control design criterion for prestressed concrete (PSC) members is stricter than conventional reinforced concrete (RC) members. In particular, it is stipulated that the net tensile stress of prestressing strands should be controlled under 250 MPa (36.3 ksi) in the serviceability design of PSC members belongi...

Core-filling method has been actively utilized to improve the shear capacity of hollow-core slabs (HCSs). However, when a high shear force is applied, slip may occur at the interface between HCS unit and core-filling concrete due to a poor bond condition, which can significantly reduce the shear strengthening effect of the core-filling method. Neve...

This study presents an analysis model to estimate the shear strength of a reinforced concrete (RC) member with corroded tensile reinforcements. The thick-walled cylinder theory was modified to fit the dual potential capacity model to reflect interdependent failure mechanisms, including the degradation effect of bonds in corroded tensile reinforceme...

The structural performance of reinforced concrete (RC) members affected by alkali–silica reaction (ASR) is difficult to predict because of the multi-scale phenomena. Recent structural tests reveal that the performance of RC members also depends on ASR-induced crack patterns, including localized cracks and dispersed microcracks. Additionally, micros...

This paper presents an experimental shear test performed to investigate the web‐shear capacity of composite hollow‐core slabs (HCS) with cast‐in‐place (CIP) concrete. Five HCS specimens are fabricated, and the presence of a topping slab and number of cores strengthened by core‐filling concrete are set as key test variables. The shear force–displace...

In this study, shear tests were conducted to investigate the shear resistance mechanisms of Gerber precast concrete (GPC) girders consisting of PC end units, PC girder units, and cast-in-place concrete. To this end, individual PC end-member and mid-girder specimens were fabricated along with five GPC girder specimen with CIP concrete. The key test...

This study aims to investigate the crack-filling effect of gel generated by the alkali–silica reaction (ASR) on the mechanical behavior of concrete and propose an analytical model to predict the compression behavior of ASR-damaged concrete. To identify the mechanical contribution of the gel-filling cracks, the distribution of the chemical compositi...

Alkali-silica reaction (ASR) causes cracks in concrete, leading to degradation of the mechanical properties of concrete. This study proposed an analytical model for compression behavior of concrete affected by ASR. To this end, the effect of crack pattern and mechanical contribution of ASR gel filling the cracks to the recontact and shear stresses...

The core-filling method, one of the shear strengthening methods of prestressed hollow-core slabs (PHCSs), has been widely applied on construction sites because of its easy reinforcement procedures. However, since there are no details for sufficient composite behavior between PHCS and core-filling concrete at the inner surface of the hollow core, in...

Post-tensioning in flat plate slabs provides the advantage of deflection and crack control under service loads, and can reduce slab thickness. However, due to the reduced slab thickness, post-tensioned flat plate slabs may be susceptible to punching shear failure under ultimate load. This study performed experimental research of the punching shear...

This study investigates the time-dependent mechanical properties of concrete deteriorated by the alkali–silica reaction (ASR). Previous analytical and experimental studies have indicated the positive impact of ASR gel in the cracks against mechanical damage in concrete. To study the effects of ASR gel on cracked concrete, groups of cylinder specime...

The expansion of concrete members due to the alkali-silica reaction (ASR) is influenced by various factors such as temperature, humidity, aggregate size, aggregate reactivity, and alkali components; among these factors, the aggregate size induces a pessimum effect in which maximum expansion due to the ASR appears in aggregates of a specific size. T...

In this study, experiments were conducted to evaluate the flexural performance of prestressed hybrid wide flange (PHWF) beams with hollowed steel webs. A total of four PHWF beams were fabricated, where the width and spacing of the steel webs and the presence of cast-in-place (CIP) concrete were set as the main test parameters, and their flexural be...

The dual potential capacity model was developed in the authors’ previous studies to estimate the shear strengths of reinforced concrete members, in which the shear crack concentration factor was adopted as the key concept of the proposed approach. In this study, a shear test program was carefully prepared and conducted on five reinforced concrete b...

In recent years, a variety of strengthening methods have been developed to improve the seismic performance of reinforced concrete (RC) frame structures with non-seismic details. In this regard, this study proposes a new type of seismic strengthening method that compresses prefabricated precast concrete (PC) walls from the outside of a building. In...

Prestressed hollow core slabs (PHCSs) have commonly been applied to long-span structures, due to their excellent flexural capacity and deflection control performance. However, in quite a few cases, the web-shear strength at member ends subjected to high shear forces is insufficient, because the web of the PHCS is very thin, making it difficult to p...

The prestressed hollow-core slab (PHCS) system is one of the most commonly-adopted precast concrete flooring systems, which can optimize productivity and structural efficiency. Since PHCS members are typically produced by the extrusion method in long-line precast plant, it is extremely difficult to provide shear reinforcements due to the automated...

The ACI 318‐14 building code requirements specify that the net tensile stresses of prestressing strands under service loads (Δfps) shall be limited to 250 MPa for proper crack control of prestressed concrete (PC) members which are classified as Class C. However, as high‐strength prestressing strands with a tensile strength of 2,400 MPa have recentl...

Half precast concrete slabs with inverted multi-ribs (Joint Advanced Slab, JAS), which enhance composite performance between slabs by introducing shear keys at connections between the slabs and improve structural performance by placing prestressing tendons and truss-type shear reinforcements, have recently been developed and applied in many constru...

In this study, shear tests were conducted to investigate the effects of longitudinal reinforcement corrosion on the shear capacity of reinforced concrete (RC) members with transverse reinforcement. To this end, a total of eight test specimens were fabricated, and the corrosion rates and anchorage details of rebars were set as test variables. In add...

The optimized-section precast slab (OPS) is a half precast concrete (PC) slab that highlights structural aesthetics while reducing the quantity of materials by means of an efficient cross-sectional configuration considering the distribution of a bending moment. However, since a tapered cross section where the locations of the top and bottom flanges...

In current design codes, crack control design criterion for prestressed concrete (PSC) members is stricter than conventional reinforced concrete (RC) members. In particular, it is stipulated that the net tensile stress of prestressing strands should be controlled under 250 MPa in the serviceability design of PSC members belonging to the Class C cat...

In recent years, high strength 7-wire strands that have a 2,400 MPa tensile strength were developed, for which the serviceability check specified in ACI318-14 and KCI 2012 need to be reviewed. The current design codes (KCI 2012 or ACI318-14) permitted that the tensile stress of reinforcing bars at service loads can be assumed as two-thirds of their...