• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.69-89
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• 2009

Reinforced and prestressed concrete (RC and PC) thin walls are crucial to the safety and serviceability of structures subjected to shear. The shear strengths of elements in walls depend strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees (Fenves 2005) to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS) (Zhong 2005, Mo et al. 2008). CSMM for PC is being currently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). In this paper, the CSMM for RC/PC in material scale is first introduced. Basically, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, are determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale is then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally the formulated results with RC/PC plane stress elements are implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique is validated by comparing the simulated responses of RC shear walls subjected to reversed cyclic loading and shake table excitations with test data. The response of a post tensioned precast column under reversed cyclic loads has also been simulated to check the accuracy of SCS which is currently under development. This multiscale modeling technique greatly improves the simulation capability of RC thin-walled structures available to researchers and engineers.

• Journal of the Korean GEO-environmental Society
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• v.9 no.4
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• pp.23-36
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• 2008

Soil nailing system can be mentioned to a method of supporting as the shear strength of in-situ soils is increased by passive inclusions. In the general soil nailing system, facing walls are used in two kind of a lattice concrete block or a cast in placed concrete wall. A case of lattice concrete blocks is used in slow slopes greater than 1(V):0.7(H). Also, a case of a cast in placed concrete wall is used in steep slopes less than 1(V):0.5(H). The cast in placed concrete walls are constructed to 30 cm thick together with a shotcrete facing. In this study, the assembling soil nailing method as a new soil nailing system will be proposed. This method is assembly construction using precast concrete panels with 20 cm thick. So, the ability of construction and the quality of facings can be improved more than a conventional soil nailing system. This method can be obtained the effects that a global slope stability increase, as precast concrete panels are immediately put on cutting face after excavating a slope. In this study, confining effects of concrete panels using the assembling soil nailing system were found out by large scaled load tests. In the tests, the load-settlement relationship to an assembling soil nailing system due to the stiff facings as concrete panels appeared to be better than a typical soil nailing system with shotcrete facings.

• Journal of the Korean Wood Science and Technology
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• v.49 no.4
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• pp.336-359
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• 2021

In this study, hybrid CLT research and development trends were analyzed to improve the low rolling shear strength of CLT, a large wooden panel used in high-rise wooden buildings. Through this, basic data that can be used in research and development directions for localization of CLT were prepared. As a way to improve the low rolling shear strength, the use of hardwood lamina, the change of the lamina arrangement angle, and the use of structural composite materials are mainly used. Rolling shear strength and shear modulus of hardwood lamina are more than twice as high as softwood lamina. It confirmed that hardwoods can be used and unused species can be used. Rolling shear strength 1.5 times, shear modulus 8.3 times, bending stiffness 4.1 times improved according to the change of the layer arrangement angle, and the CLT strength was confirmed by reducing the layer arrangement angle. Structural wood-based materials have been improved by up to 1.35 times MOR, 1.5 times MOE, and 1.59 times rolling shear strength when used as laminas. Block shear strength between the layer materials was also secured by 7.0 N/mm², which is the standard for block shear strength. Through the results of previous studies, it was confirmed that the strength performance was improved when a structural wood based materials having a flexural performance of MOE 7.0 GPa and MOR 40.0 MPa or more was used. This was determined based on the strength of layered materials in structural wood-based materials. The optimal method for improving rolling shear strength is judged to be the most advantageous application of structural wood based materials with strength values according to existing specifications. However, additional research is needed on the orientation of CLT lamina arrangement according to the fiber arrangement of structural wood-based materials, and the block shear strength between lamina materials.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.18 no.3
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• pp.99-106
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• 2018

Mucolipidosis type III (pseudo-Hurler polydystrophy) is a mucolipids degrading disorder caused by a mutation in the GNPTAB gene and is inherited by autosomal recessive. It is diagnosed by examining highly concentrated mucolipids in blood and the diagnosis can be confirmed by genetic testing. Mucolipidosis type III is a rare and progressive metabolic disorder. Its initial signs and symptoms usually occur around 3 years of age. Clinical manifestations of the disease include slow growth, joint stiffness, arthralgia, skeletal abnormalities, heart valve abnormalities, recurrent respiratory infection, distinctive facial features, and mild intellectual disability. Here, we are presenting two siblings of mucolipidosis type III, a 4-year-old female and a 2 years and 7 months old male with features of delayed growth and coarse face. The diagnosis was confirmed by [c.2715+1G>A(p.Glu906Leufs*4), c.2544del(p.Glu849Lysfs*22)] mutation in targeted gene panel sequencing. In this case, c.2544del is a heterozygote newly identified mutation in mucolipidosis type III and was not found in the control group including the genome aggregation database. And it is interpreted as a pathogenic variant considering the association with phenotype. Here, we report a Korean mucolipidosis type III patients with novel mutations in GNPTAB gene who have been treated since early childhood. Owing to recent development of molecular genetic techniques, it was possible to make early diagnosis and treatment with pamidronate was initiated appropriately in case 1. In addition to these supportive therapies, efforts must be made to develop fundamental treatment for patients with early diagnosis of mucolipidosis.