Dae-Jin Kim

Kyung Hee University · Department of Architectural Engineering

This paper presents a generalized finite element method (GFEM) based on the solution of interdependent global (structural) and local (crack)-scale problems. The local problems focus on the resolution of fine-scale features of the solution in the vicinity of three-dimensional cracks, while the global problem addresses the macro-scale structural beha...

The main feature of partition of unity methods such as the generalized or extended finite element method is their ability of utilizing a priori knowledge about the solution of a problem in the form of enrichment functions. However, analytical derivation of enrichment functions with good approximation properties is mostly limited to two-dimensional...

Openings in RC flat-plate slabs are one of the critical factors that influence the punching shear strength of the slab and determine its thickness in the vicinity of the slab-column joint. This study experimentally investigates the effects of openings on the punching shear strength of flat-plate slabs without shear reinforcement. Tests were perform...

A generalized fiber beam element formulation is proposed to accurately capture the formation of multiple plastic regions with a coarse mesh, which usually occurs in the process of structural collapses. The strong gradient of displacement near plastic regions in a fiber beam element can be accurately described using a special plastic enrichment func...

This paper presents a case study on the rehabilitation of a fire-damaged structure and describes the results of a site investigation and tests, leading to a plan for the rehabilitation of the structure. The fire took place in the main control room of a thermal power plant and lasted about three hours until it was finally extinguished. To set up a r...

This study introduces a novel concrete-filled tube (CFT) column system featuring a steel tube comprised of four internal triangular units. The incorporation of these internal triangular units serves to reduce the width-thickness ratio of the steel tube and augment the effective confinement area of the infilled concrete. This design enhancement is a...

In this study, statistical assessment was performed on student engagement in online learning using the k-means clustering algorithm, and their differences in attendance, assignment completion, discussion participation and perceived learning outcome were examined. In the clustering process, three features such as the behavioral, emotional and cognit...

In this paper, a new deck plate system, in which the top chords are infilled with high-performance cement-based material such as high-strength mortar and UHPC (ultra-high performance concrete), was proposed. The bending capacity of the proposed deck plate system at the construction stage was investigated by performing a four-point bending test on s...

This study examines the structural relationship among key factors influencing student satisfaction and achievement in online learning. A structural model was developed by considering course structure, student–student interaction, instructor presence, student engagement, student satisfaction and achievement as key factors. In order to verify the eff...

This paper investigates the relationship between the influential factors related to higher education and job satisfaction of engineering graduates in Korea. The education factors considered in this study can be categorized into three groups: those related to personal information, satisfaction with higher-education quality, and participation in care...

In this study, a structural health monitoring system for cable-stayed bridges is developed. In the system, condition assessment of the structure is performed based on measured records from seismic accelerometers. Response indices are defined to monitor structural safety and serviceability and derived from the measured acceleration data. The derivat...

Torsional deformation may occur in plan-asymmetric wall structures during seismic events. In most current seismic design codes, the torsional deformation is handled using the concept of design eccentricity, in which design loads may be excessively amplified. This approach has limitations in accurately estimating the torsional deformation of the pla...

This article presents generalized finite element formulation for plastic hinge modeling based on lumped plasticity in the classical Euler–Bernoulli beam. In this approach, the plastic hinges are modeled using a special enrichment function, which can describe the weak discontinuity of the solution at the location of the plastic hinge. Furthermore, i...

In this study, a push-out test was performed on steel pile caps strengthened with newly proposed perfobond shear connectors, and the test results were analysed and subsequently discussed. The newly proposed perfobond connector can greatly simplify the complicated processes required for the conventional pile cap strengthening method with steel rebar...

Quality function deployment and TRIZ method are widely used to develop new products in the manufacturing industry. These methods are known to be extremely effective for cost reduction and quality improvement. However, unlike the general manufacturing process, the manufacturing of an exportable modular building system involves many sub-processes tha...

Plastic greenhouses are often designed with low levels of safety. As a result there has been an increasing number of structural failures due to abnormal climatic conditions such as heavy snow and strong winds. Standardised prototypes are often used to facilitate the design process, but these prototypes cannot withstand every extreme loading conditi...

Purpose This paper aims to propose a generalized finite element technique that can accurately approximate the solution of the flexural-shear cantilever model of wall-frame structures proposed by Heidebrecht and Stafford Smith. Design/methodology/approach This approach adopts scaled monomials as enrichment functions, and they are highly effective...

This paper proposes a new steel concrete composite beam that has a similar shape to the conventional steel wide flange beam, but whose lower flange has a tubular shape with infilled concrete. It has openings in the web for perfect integration between concrete and steel materials, and the tubular lower flange is reinforced with steel rebars to enhan...

This study presents a systematic approach for the development of an efficient steel beam section for modular construction based on Six-Sigma. Although the Six-Sigma is frequently implemented in manufacturing and other service industries, it is a relatively new concept in the area of building design and construction. As a first step in this approach...

The conventional strengthening strategy on the connection between the steel pile cap and reinforced concrete footing requires a series of complicated processes such as the distribution of reinforcing bars, their anchorage into concrete, and the usage of shear keys. This study investigates the structural performance of steel pile caps strengthened w...

Construction equipment is often shared among many construction projects. In a real construction project, supply of this critical equipment is often limited, which often generates negative impacts on project performance. Multiple shifts are very effective and efficient for achieving schedule acceleration while resolving resource conflicts among proj...

This study proposes a new type of the perfobond shear connector, which can be used to strengthen the steel pile cap embedded into the structure foundation, and evaluates its pull-out resistance capacity by performing a test on ten specimens. Test parameters include the embedment length of the shear connector, existence of transverse rebars passing...

This paper proposes a modified three-dimensional capacity spectrum method to efficiently evaluate the seismic behavior of a building structure with asymmetric walls, where twisting is induced due to lateral loading. This method utilizes the demand surfaces and capacity curves that are created based on the inelastic earthquake response and seismic c...

This paper introduces the generalized finite element method with global-local enrichment functions using the preconditioned conjugate gradient method. The proposed methodology is able to generate enrichment functions for problems where limited a-priori knowledge on the solution is available and to utilize a preconditioner and initial guess of high...

The use of steel-concrete composite members has been significantly increased as they have the advantages of the reduction of cross sectional areas, excellent ductility against earthquake loadings and a longer life span than typical steel frame members. The increased use of composite members requires an intensive study on the shear resistance evalua...

The current American Concrete Institute(ACI), Canadian Standard Associate(CSA) and CEB-FIP Model Code 2010 provisions on the shear strength of a simply supported deep beam suggest that deep beams should be designed using the strut-and-tie model. Although this is a useful methodology to design members in disturbed regions, the quality of the design...

An experimental test was performed to evaluate the seismic resistance of reinforced concrete beam-column joints rehabilitated with FRP sheets and Buckling Restrained Braces (BRBs). Six beam-column joints were rehabilitated and tested. The test results were compared in terms of hysteresis loops, stiffness degradation, energy dissipation and ductilit...

A new type of fiber-reinforced polymer (FRP) shear reinforcement is proposed for reinforced concrete beams. The new FRP shear reinforcement consists of FRP plate material with openings. The performance of the proposed shear reinforcement was investigated by performing tests on nine concrete beam specimens with a shear span-depth ratio of 2.4. Test...

This paper focuses on the shear strength of a fiber reinforced polymer (FRP) reinforced concrete deep beam without any web reinforcement, and proposes a new effectiveness factor for concrete struts for its design using the strut-and-tie model. A total of fifteen deep beam specimens reinforced with steel, AFRP, and CFRP rebar were tested by consider...

This paper presents an extension of a two-scale generalized finite element method (GFEM) to three-dimensional fracture problems involving confined plasticity. This two-scale procedure, also known as the generalized finite element method with global-local enrichments (GFEMgl), involves the solution of a fine-scale boundary value problem defined arou...

Prediction and simulation of load-related reflective cracking in airfield pavements require 3D models in order to accurately capture the effects of gear loads on crack initiation and propagation. Furthermore, the size relations between aircraft landing gear, pavement area and reflective cracks make this a multi-scale problem. This paper presents a...

The current American Concrete Institute (ACI) and Canadian Standard Association (CSA) code provisions on the shear strength of a simply supported concrete deep beam and its end anchorage details suggest that deep beams should be designed using the strut-and-tie model approach. Although this is a useful methodology to design members in disturbed reg...

Partition of unity methods like the GFEM, rely on closed-form analytical enrichment functions. However, only limited a priori knowledge about the solution is available for many problems of engineering relevance. Control of discretization errors in this class of problems requires mesh refinement which offsets some of the advantages associated with t...

The current ACI code provision on the shear strength of a simply supported deep beam and its end anchorage details suggests that deep beams should be designed using the strut-and-tie model provided in its appendix. Although this is a useful methodology to design members in disturbed regions, the quality of the design is highly dependent on the trus...

This paper presents a generalized finite element method (GFEM) for crack growth simulations based on a two-scale decomposition of the solution—a smooth coarse-scale component and a singular fine-scale component. The smooth component is approximated by discretizations defined on coarse finite element meshes. The fine-scale component is approximated...

This paper shows that the generalized finite element method with global–local enrichment functions (GFEMgl) can be implemented non-intrusively in existing closed-source FEM software as an add-on module. The GFEMgl is based on the solution of interdependent global (structural) and local (crack) scale problems. In the approach presented here, an init...

The recycling of industrial waste such as bottom ash from furnaces is an important issue in construction industry, since it enables reduction in construction cost and has beneficial effect on the environment. In this study, we have investigated the bond characteristics of steel deformed bars embedded in artificial lightweight aggregate concrete whi...

The bond behavior of reinforcing bars is an important issue in the design of reinforced concrete structures and the use of fiber reinforced polymer (FRP) rebars is a promising solution to handle the problems of steel reinforcement corrosion. This study investigates the bond characteristics of carbon and aramid FRP (CFRP and AFRP) bars embedded in n...

Attenuations of the fundamental longitudinal guided wave mode propagating in buried steel pipes, which transport different fluids, are numerically investigated. From the attenuation dispersion curves, two specific frequency values (1 MHz, 2.65 MHz) are selected to capture attenuation characteristics and, then the previously introduced parametric de...

This paper presents a parallel generalized finite element method (GFEM) that uses customized enrichment functions for applications where limited a priori knowledge about the solution is available. The procedure involves the parallel solution of local boundary value problems using boundary conditions from a coarse global problem. The local solutions...

This paper focuses on the effect of shear force and torsion moment on the plastic collapse load for circumferentially flawed pipe sections with small and large diameter-thickness (D/t) ratios. Rigorous elastic-plastic finite element analyses are performed using bilinear kinematic hardening and Von Mises yield criteria. The comparison between the nu...

This paper presents an analysis of interacting cracks using a generalized finite element method (GFEM) enriched with so-called global-local functions. In this approach, solutions of local boundary value problems computed in a global-local analysis are used to enrich the global approximation space through the partition of unity framework used in the...

This paper presents a procedure to build enrichment functions for partition of unity methods like the generalized finite element method and the hp cloud method. The procedure combines classical global–local finite element method concepts with the partition of unity approach. It involves the solution of local boundary value problems using boundary c...

Existing generalized or extended finite element methods for modeling cracks in three-dimensions require the use of a sufficiently refined mesh around the crack front. This offsets some of the advantages of these methods specially in the case of propagating three-dimensional cracks. In this paper, a strategy to overcome this limitation is investigat...

This paper presents a procedure to build C k , k arbitrarily large, generalized finite element (FE) shape functions defined on non-struc-tured finite element meshes. The functions have the same support as corresponding global FE Lagrangian shape functions. Meshes with both convex and non-convex clouds (set of elements sharing a vertex node), can be...

Shear strength of structural deep beams is important in design. This paper focuses on the shear strength of deep beams combined with anchorage failure, based on upper bound solutions in the theory of plasticity. The solutions showed that the shear strength combined with anchorage failure is lower than other shear strength due to web crushing in som...

The Generalized Finite Element Method (GFEM) allows straightforward construction of discrete solution spaces using non-polynomial functions while preserving the sparsity of global matrices. These functions are chosen carefully to mimic known properties of the function to be approximated. The GFEM has been successfully applied to the simulation of d...

The main feature of partition of unity methods such as hp-cloud, generalized and extended finite element methods is their ability of utilizing a priori knowledge about the solution of a problem in the form of enrichment functions. Linear combination of partition of unity shape functions can reproduce exactly the enrichment functions and thus their...