In current research, it was attempted a preliminary design and evaluation of non-uniform ultra high-strength concrete (UHSC) truss members. UHSC used here has the compressive strength of 180 MPa, the tensile strength of 8 to 20 MPa, and the tensile strain after cracks up to 2%. By the three-dimensional finite element stress analysis as well as strut-tie approach on concrete solid beams, the non-uniform truss shape of UHSC truss was designed with the architectural esthetic concept. In a series of examples, to compare with conventional concrete members, the proposed UHSC truss members have advantages in capabilities of the slender design with minimum weight with high performances under transverse loadings as well as the aesthetically non-uniform design for spatial structures.

The degree of interaction is a very important factor determining stiffness, strength and deflection performance in the composite beam. Because this synthesis is made through the shear connector, the structural performance of the shear connector is very important. In this study, the connection method was developed using the driving pin to solve the problem of conventional welding connection method. To verify the structural performance of the developed connection method, the push-out test was performed and analyzed against numerical analysis results. Based on the results of the analysis, it is deemed that the structural performance can be obtained by joining the shear connection in proposed method.

This study investigated a bio-tensegrity structural system that combines the characteristics of a general tensegrity structural system with a biological system. The final research objective is to accomplish a changeability for the structural system as like the movement of the natural bio-system. In the study, we present a shape finding procedure for the two stage bio-tensegrity system model inspired by the movement pattern of animal backbone. The proposed system is allowing a dynamic movement by introducing the concept of “saddle” for the variable bio-tensegrity structure. Several shape finding analysis example and results are presented and shows a efficient validation and suitability.

Subsurface cavities in the asphalt pavement which can cause road depression and cave-in accidents influence on the safety of pedestrians and vehicle drivers in the urban area. The existence of subsurface cavity can increase the tensile strain at the bottom of asphalt layer which is an indicator of fatigue cracking potential, and leads to the weakening of the pavement structural capacity. In this study, the finite element (FE) analysis was conducted to examine the relationship between the critical pavement responses and influencing factors, such as cavity depth and size, asphalt layer thickness, and asphalt concrete modulus. The surface deflections and tensile strains calculated from the ABAQUS FE program were compared to those from ILLIPAVE. It is found from this comparison that there are a good relationship between two analysis results. A three dimensional finite element model which is essential to simulate the hexahedral cavity were used to generate the synthetic database of critical pavement responses. To validate the developed model, the deflection data obtained from field Falling Weight Deflectometer (FWD) testing in four different locations were compared to FE deflections. It is found that the center deflections obtained from the FWD testing and FE analysis are similar to each other with an error values of 2.7, 4.4, 5.5, and 11.9 % respectively. The FE model developed in this study seems to be acceptable in simulating actual field cavity condition. On the basis of the data in the database, various analyses were conducted to estimate the effect of influencing factors on the critical pavement responses. It was found that the tensile strain at the bottom of asphalt layer is affected by all the factors but the most affected by the cavity depth and asphalt concrete modulus. Further studies are recommended to properly account for the effect of cavity’s geometry to pavement response.

The improvement in computing systems and sensor technologies devotes to conduct data-driven structural health monitoring algorithms for existing civil infrastructures. Despite of the development of techniques, the uncertainty oriented from the measurement results in the discrepancy to the actual structural parameters and let engineers or decision makers hesitate to adopt such techniques. Many studies have shown that the modal identification results can be affected by the uncertainties due to the applied methods and the types of loading. This paper aims to compare the performance of modal identification methods using Structural Modal Identification Toolsuite (SMIT) which has been developed to facilitate multiple identification methods with a user-friendly designed platform. The data fed into SMIT processes three stages for the comprehensive identification including preprocessing, eigenvalue estimation, and post-processing. The seismic and white noise response for shear frame model was obtained from numerical simulation. The identified modal parameters is compared to the actual modal parameters. In order to improve the quality of coherence in identified modal parameters, several hurdles including modal phase collinearity and extended modal amplitude coherence were introduced. Numerical simulation conducted on the 5 dof shear frame model were used to validate the effectiveness of using these parameters.

Owing to the development in information and communications technologies have improved the technology for high-speed transmission of massive data, which has changed closed-circuit television (CCTV) video transmission technology. In particular, digitization of the CCTV video format and streaming technology has made it possible to minimize transmission loss and integrate video transmission and camera control(pan/tilt). It has also become possible to provide additional services like remote emergency warning broadcasting with just Internet Protocol (IP). However, because of the structural problems of IP, these changes have also brought about the threat of hacking of CCTV monitoring systems. In this study, we propose a methode to optimize network management by examining cases of enhancement of operational efficiency and security by improving the structure of CCTV monitoring network.

In this paper, comparative analysis of the 9.12 Gyeongju and 11.15 Pohang earthquakes was conducted in order to provide probable explanations and reasons for the damage observed in the 11.15 Pohang earthquake from both earthquake and structural engineering perspectives. The damage potentials like Arias intensity, effective peak ground acceleration, etc observed in the 11.15 Pohang earthquake were generally weaker than those of the 9.12 Gyeongju earthquake. However, in contrast to the high-frequency dominant nature of the 9.12 Gyeongju earthquake records, the spectral power of PHA2 record observed in the soft soil site was highly concentrated around 2Hz. The base shear around 2 Hz frequency was as high as 40% building weight. This frequency band is very close to the fundamental frequency of the piloti-type buildings severely damaged in the northern part of Pohang. Unfortunately, in addition to inherent vertical irregularity, most of the damaged piloti-type buildings had plan irregularity as well and were non-seismic. All these contributed to the fatal damage. Inelastic dynamic analysis indicated that PHA2 record demands system ductility capacity of 3.5 for a structure with a fundamental period of 0.5 sec and yield base shear strength of 10% building weight. The system ductility level of 3.5 seems very difficult to be achievable in non-seismic brittle piloti-type buildings. The soil profile of the PHA2 site was inversely estimated based on deconvolution technique and trial-error procedure with utilizing available records measured at several rock sites during the 11.15 Pohang earthquake. The soil profile estimated was very typical of soil class D, implying significant soil amplification in the 11.15 Pohang earthquake. The 11.15 Pohang earthquake gave us the expensive lesson that near-collapse damage to irregular and brittle buildings is highly possible when soil is soft and epicenter is close, although the earthquake magnitude is just minor to moderate (M 5+).

이 연구는 강원지역 산지에 자연적으로 성립하여 잔존하고 있는 산림유존목(가슴높이 줄기둘레 300㎝이상)의 체계 적 보전 및 관리를 위한 기초자료(분포실태와 생장특성 그리고 생육임분의 구성적 특성 등)를 제공하는데 그 목적이 있다. 금번 조사에서는 강원지역 산지에서 모두 19종 434개체(침엽수 4종 228개체, 활엽수 15종 206개체)의 산림유존목이 분포하고 있음을 확인하였고, 주목이 전체의 약 46.7%인 203개체로 가장 많은 것으로 나타났다. 줄기둘레는 평균 404㎝(침엽수 373㎝, 활엽수 421㎝)이었고, 설악산 피나무 복간목이 1,113㎝로 가장 크게 났다. 수고와 수관폭은 각각 평균 15.4m, 10.0m이었다. 입지특성은 수종별로 다소 차이가 있지만 해발고도는 대개 1,000m이상, 사면경사도는 25°이상, 사면방위는 북향, 미세지형은 사면상부 등에서 상대적 출현빈도가 높은 경향이었다. 산림유존목 생육임분의 단위면적당(/100㎡) 구성적 특성을 보면, 총피도는 평균 294%(최대 475%), 출현종수는 평균 36종(최대 60종), 종다양 성 지수(H‵) 평균 2.560(최대 3.593), 그리고 수관울폐도는 평균 84.8%(최대 94.6%), 그리고 흉고단면적(/ha)은 평균 52.7㎡(최대 116.4㎡; 산림유존목 개체 30.0㎡, 기타 교목성 개체 22.7㎡)로 나타났다. 한편, 강원지역 산림유존목 개체의 동태 유형을 추정한 결과, 생육환경과 교란강도에 따라 다소 차이는 있으나 “후계수가 낮은 밀도이지만 지속적 으로 공급되는 유형(신갈나무, 전나무, 피나무, 산돌배)”, “후계수가 완전히 단절된 유형(소나무)”, “후계수가 최근 또는 상당기간 단절된 유형(분비나무, 굴참나무, 박달나무)”, 그리고 “후계수가 주기적으로 단절과 공급이 반복되는 유형(호랑버들, 졸참나무)”등 크게 4가지 유형으로 구분되었다.

The TRM method applied in this study is a method aiming at long span and low girder hight of the temporary bridge. When the preload is introduced to the girder member and the preload is removed after by welding the stiffener, a prestress is introduced through the stiffener to increase the load capacity of the member. Therefore, in this study, the structural performance improvement through the application of the TRM method was verified experimentally by the bending tests of the specimens with and without the TRM method.