Advanced Materials Research Vol. 831

Abstract: Studies in the structural systems include two main approaches, design and analysis, which require response evaluation of structures to the external loads including live and dead loads. Structures behave statically and dynamically for static and dynamic loads, respectively. One of the most important dynamic loads acting on a structure is earthquake force. In order to find responses of structures subjected to earthquake, several schemes of direct integration can be used. This study deals with two methods of calculating dynamic responses of a single-degree of freedom oscillator, i.e., central difference method (CDM) and Newmarks beta method (NBM), using recorded ground acceleration for 60seconds. The maximum relative acceleration is obtained to determine maximum relative displacement by which estimation of quality and quantity of failure occurred to a structure for a given earthquake is provided. Firstly both CDM and NBM are discussed. Second, for a specific damping ratio dynamic responses are evaluated for periods of range in between 0.1sec to 1.5sec to evaluate the effects of period on responses of system. Third, the effects of damping on dynamic responses of SDOF system are evaluated by considering different damping coefficients from ζ=0 to 0.5. The results are compared and discussed to investigate the range of periods and damping factors where methods can provide a better estimation of responses.

Abstract: In recent years, temporary housing built in a stricken area has been built by steel construction. But temporary housing could not be built unless an engineer went to a stricken area and the building could not carry a short-time loading like an earthquake or wind loadings. This research aims to develop the permanent box unit construction which is carried and assembled a part by victims. Analysis model used the vinylon fiber reinforced concrete in order to make a concrete ductile without using a reinforced rod. The linear model was analyzed with FEM software. The analysis was carried out and the validity of a temporary housing was confirmed.

Abstract: The design guideline of R/C shell has not been established in Japan because of several technical difficulties. It is possible to analyze the strength of R/C shell by means of the finite element method but precise experiments are required to verify the analytical results reliably. Therefore, this research conducted the loading test of R/C arch as the basic form of R/C shell. Two kinds of R/C arch without initial imperfection were set under several loading conditions and were analyzed the load carrying characteristics of R/C arch with idealized pinned support. Consequently, it became clear that the axial stress and flexural stress of R/C arch depend on the shape of R/C arch and these combinations strongly influenced the deformation behavior and the strength characteristics of R/C arch.

Abstract: Seismic isolation system is an example of passive control system that effectively improves the performance of structures. This research discusses the seismic performance of a elastomeric base isolation system which provide the combined features of vertical load support, horizontal flexibility and energy absorbing capacity, utilizing shape memory alloys that provides re-centering force and additional damping in the system. Also this paper compares the effect of such alloys with memory effect and/or superelasticity (with pre-straining) in base isolated structure. To provide such comparison, a nonlinear structural model has been developed on some benchmark control problems and some health monitoring evaluation criterias are used. The smart base isolation utilizes the different responses of shape memory alloys at several levels of strain to control the displacements of the rubber bearing and base shear at excitation level. Furthermore the proposed based isolation systems has enhanced performance in terms of response reduction and re-centering capacity.

Abstract: This paper represented the numerical analysis of the tunnel lining which was used for maintaining the old tunnel. The tunnel lining was made from FRP corrugated sheet that supported the lining concrete in the tunnel and flowed the water or / and the moisture swept on the tunnel surface. The FRP sheet was supported by the anchor bolts. In numerical analysis, the finite element degenerate shell was adopted to represent the FRP behavior. Firstly, the proposed FRP sheet was adopted and the distribute load equivalent to the concrete peeled from the tunnel lining was applied and the stresses of the FRP sheet, the tensile force of bolts and the deflection of FRP sheet were investigated. Then, secondary, the FRP corrugated sheet with longitudinal cover strip was investigated. From the numerical analysis, the effectiveness of the FRP corrugated sheet was confirmed.

Abstract: This paper presented the result of analysis about R/C arch by use of finite element method. The design method for R/C shell has not been established due to its numerical difficulties. Using the finite element method, it was possible to analyze these structures. However, the precise experiments were required to verify the reliability of these analyses and it was necessary to improve the numerical analyses. An R/C arch is a basic form of the R/C shell. Under various conditions, that was, R/C arch without initial imperfection, different rise-span ratio, three types of loading points and supporting conditions, loading tests of R/C arch were performed. After experiment, analysis was also carried out. And as the result compared experimental and numerical results, accuracy of this analysis method was elucidated.

Abstract: This study has compared the equivalent external pressure coefficients, (GC_pf)_eq, with 6 wind load provisions and wind tunnel test data. The wind load provisions are the ASCE 7-10, NBCC 2010, AS/NZS 2011, EN 2005, AIJ 2004 and KBC 2009. Experiment data on low-rise building have been obtained at the University of Western Ontario (UWO) to contribute to the NIST aerodynamic database [. For the experiment, a model with 1:12 of roof slope and 4.9 and 12.2m of eave height was used under open terrain conditions (See also Ref. [). (GC_pf)_eq was re-normalized based on the external pressure coefficients, GC_pf, of ASCE 7-10. When compared to (GC_pf)_eq of the experiment data with 4.9m of eave height, consequently, ASCE 7-10 (81%), NBCC 2010 (84%), AS/NZS 2011 (70%), AIJ 2004 (68%) and KBC 2009 (53%) were all underestimated. Among them, KBC 2009 reveals the lowest value. On the contrary, EN2005 was overestimated with 122%. When the eave height was 12.2m, in addition, the same pattern was observed in most codes. EN2005 was slightly overestimated with 115%.

Abstract: Fatigue damage increases with applied load cycles in a cumulative manner. Cumulative fatigue damage analysis plays a key role in life prediction of structures subjected to field load histories. Steel structures of substations are subjected to a large number of repetitive loading of different magnitudes caused mainly by mechanical equipment such as gas insulated switchgear (GIS). In this paper, a method is presented to predict the fatigue damage of the steel structures of a 153kV substation using dynamic characteristics. Through the field measurements and the fatigue analysis, it was observed that the accumulated fatigue damage was very small after a year of operation and the amount of accumulated fatigue damage will be smaller than 0.2 until the end of the working life. The structural safety of the 153kV substation can be guaranteed by the normal inspection.

Abstract: Recently offshore wind turbines have been constructed and planned in Korea. However, seismic stability was not extensively examined, although relatively small earthquakes frequently occur and the occurrence trend is increasing. This study intends to analyze the seismic stability of a wind turbine foundation based on KPMDC, KBDC, and DNV OS. The foundation considered has a conical concrete base under a steel shaft supporting the 5 MW wind turbine. This study performed 3D response spectrum analysis to consider turbine weight and self-weights. Analysis resultsbased on KPMDC indicatedthat very severetensile stresses in the concrete foundation near the neck bracket and pile-concrete foundation connection, which may require reinforcing.

Abstract: Coupling beams resist lateral loads efficiently is well known in coupled wall systems. In many cases, geometric limits result in coupling beams that are deep in relation to their clear span. Coupling beams with small depth-to-span ratio shall be reinforced with two intersecting groups of diagonally placed bars symmetrical along the mid-span. It's always hard to optimize construction projects. This paper used the finite element software (Abaqus) to analysis and simulate the nonlinear behavior of a new reinforcement called head bar and compared the results to the current standards.