• Computers and Concrete
• /
• v.18 no.1
• /
• pp.17-37
• /
• 2016

This paper compares the arc-length and explicit dynamic solution methods for nonlinear finite element analysis of prestressed concrete members subjected to monotonically increasing loads. The investigations have been conducted using an L-shaped, prestressed concrete spandrel beam, selected as a highly nonlinear problem from the literature to give insight into the advantages and disadvantages of these two solution methods. Convergence problems, computational effort, and quality of the results were investigated using the commercial finite element package ABAQUS. The work in this paper demonstrates that a static analysis procedure, based on the arc-length method, provides more accurate results if it is able to converge on the solution. However, it experiences convergence problems depending upon the choice of mesh configuration and the selection of concrete post-cracking response parameters. The explicit dynamic solution procedure appears to be more robust than the arc-length method in the sense that it provides acceptable solutions in cases when the arc-length approach fails, however solution accuracy may be slightly lower and computational effort may be significantly larger. Furthermore, prestressing forces must be introduced into the finite element model in different ways for the explicit dynamic and arc-length solution procedures.

• Structural Engineering and Mechanics
• /
• v.39 no.4
• /
• pp.521-539
• /
• 2011

Jilin highway concrete bridge is located in the center of Jilin City, which is positioned in the middle part in Jilin Province in the east north of China. This bridge crosses the Songhua River and connects the north and the south of Jilin City. The main purpose of damages inspection of the bridge components is to ensure the safety of a bridge and to identify any maintenance, repair, or strengthening which that need to be carried out. The damages that occur in reinforced concrete bridges include different types of cracks, scalling and spalling of concrete, corrosion of steel reinforcement, deformation, excessive deflection, and stain. The main objectives of this study are to inspect the appearance of Jilin highway concrete bridge and describe all the damages in the bridge structural members, and to evaluate the structural performance of the bridge structure under dead and live loads. The tests adopted in this study are: (a) the depth of concrete carbonation test, (b) compressive strength of concrete test, (c) corrosion of steel test, (d) static load test, and (e) dynamic load test. According to the damages inspection of the bridge structure appearance, most components of the bridge are in good conditions with the exception arch waves, spandrel arch, deck pavement of new arch bridge, and corbel of simply supported bridge which suffer from serious damages. Load tests results show that the deflection, strain, and cracks development satisfy the requirements of the standards.

• Journal of Korean Association for Spatial Structures
• /
• v.8 no.3
• /
• pp.83-90
• /
• 2008

It is hard to predict the mechanical characteristics of discontinuous stone masonry structures by the static analysis method, because of irregularity of face stones and also due to randomness of backfill materials. Inversely, one can estimate the mechanical characteristics by comparing the natural frequencies between measured and computed. The aim of this paper is to investigate the computational modeling method of ancient stone arch bridges in Korea and to find the factors influencing their dynamic characteristics. The results revealed that the rigidity of spandrel walls and backfill materials are the most important factors influencing the natural frequencies of stone arch bridges.

• KIEAE Journal
• /
• v.10 no.5
• /
• pp.151-157
• /
• 2010

This study is connected with evaluation of the progressive collapse resisting capacity for sustainable RC super tall building design. As the progressive collapse is not considered in current design codes in Korea, differences between linear static and dynamic analysis based on the GSA guidelines was analyzed for better evaluation, and the analysis model of flat plate system was determined. Finally, the progressive collapse resisting capacity was evaluated for structural system of super tall building. According to this study, the results by linear dynamic analysis were underestimated than the results by linear static analysis. Thus, the dynamic coefficient value of 2 provides conservative approach. The Effective Beam Width's model, currently used in field, is useful for the analysis about lateral force, but this model does not consider the effect of load redistribution by the slab. Hence, finite element analysis considering slab element will be needed for progressive collapse resisting capacity of the flat plate system. Finally, analysis model of 80-story building designed based on KBC(Korea Building Code) shows the weakness against progressive collapse because the DCR value is over 2. Thus, the countermeasure for alternative loading path such as installment of spandrel beam and reinforcements around slab is required to prevent the progressive collapse.

• Journal of the Korean Solar Energy Society
• /
• v.33 no.3
• /
• pp.107-113
• /
• 2013

In this study, three different types of experimental models of BIPV curtain wall units with GIGS modules were built, and their thermal and electrical performances were analyzed. The experimental results showed that the temperature of the rear side of the GIGS module with the application of an insulation in the curtain wall spandrels was higher than a GIGS module standalone by $22^{\circ}C$, which results in a reduction in the power generation of the former by 8 %. On the other hand, when ventilation was applied to the model to improve the power generation performance, the module temperature was observed to be $142^{\circ}C$ lower compared to the enclosed type, and the power generation performance improved by 5 %. It confirmed that the temperature increase in the rear side of the GIGS module with insulation layer reduced the electrical performance of the module. Based on this, it is claimed that providing sufficient ventilation at the GIGS applied spandrels contribute to improve the power generation of the GIGS module.

• Acta Via Serica
• /
• v.6 no.2
• /
• pp.1-20
• /
• 2021

The Taq-i Bustan reliefs are representative works from the Sassanian dynasty of the 4th to 7th centuries. This study analyzes the costumes depicted in the Taq-i Bustan reliefs to gain understanding of the phenomena of cultural exchange between the East and West by observing the foreign cultural elements appearing in the Sassanian costumes of that time. Literature study and artifacts analysis were conducted in parallel. External elements appearing in Taq-i Bustan's costume were Greek-Roman and Central Asian. The tunics and trousers of the gods and the trousers of kings (Ardashir II, Shapur II and Shapur III) were made of thin fabric and showed many wrinkles, a characteristic of Greek and Roman clothing. On the spandrel above the arch of the great grotto of Khusrau II are depicted the goddesses of Victory, in a Greco-Bactrian style. Among the costume elements of Taq-i Bustan, there were also Central Asian elements observed. One Central Asian costume element was the round clasp ornament for tying the trousers. The side slits and hem of the tunic were presented in the style of the Sogd clothing of Central Asia in the 6th and 7th centuries, while the pearl rounded pattern was activated in Sogd, Kucha and Kizyl in the 7th and 8th centuries. These reliefs are considered important evidence of eastern influences in Sassanian culture.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.17 no.3
• /
• pp.145-152
• /
• 2013

This study is to evaluate the thermal insulation of the curtain wall of the buildings constructed since the 1990s to the buildings currently under construction in 2011 and to provide the basic data for repairing and reinforcing and designing the thermal insulation. To this effect, the temperature difference by part was analyzed through measuring the inside and outside surface temperature of the curtain wall of the office building, and thereafter, the conditions of the thermal insulation and the thermal bridge part were examined. The result of the study is as follows; Not only in the winter season when the temperature difference between the indoor-outdoor is over $20^{\circ}C$, but also in the summer season when there is a small temperature difference, the temperature difference between the inside and outside of the frame is $2^{\circ}C{\sim}4^{\circ}C$ equally. Under such conditions as stated above, the thermal bridge occurred, which resulted from the heat flow of the steel frame part (mullion, transom), and therefore, the reinforcement of the thermal insulation is considered to be needed.

• Journal of the Korean Solar Energy Society
• /
• v.37 no.2
• /
• pp.47-57
• /
• 2017

CIGS thin film solar cells are technically suitable for BIPV applications than regularly used crystalline silicon solar cells. Particularly, CIGS PV has lower temperature coefficient than crystalline silicon PV, thus decrease in power generation is lowered in CIGS PV. Moreover, CIGS PV can decrease shading loss when applied to the BIPV system, and the total annual power generation is higher than crystalline silicon. However, there are few studies on the installation factors affecting the performance of BIPV system with CIGS module. In this study, BIPV curtain wall unit with CIGS PV module was designed. To prevent increase of temperature of CIGS PV module by solar radiation, ventilation was considered at the backside of the unit. The thermal specification and electrical performance of CIGS PV of the ventilated unit was analyzed experimentally. Non-ventilated unit was also investigated and compared with ventilated unit. The results showed that the average CIGS temperature of the ventilated curtain wall unit was $6.8^{\circ}C$ lower than non-ventilated type and the efficiency and power generation performance of ventilated CIGS PV on average was, respectively, about 6% and 5.8% higher than the non-ventilated type.

• Structural Engineering and Mechanics
• /
• v.59 no.3
• /
• pp.387-401
• /
• 2016

This paper takes a half-through steel truss arch bridge as an example. A seismic analysis is conducted with nonlinear finite element method. Contrast models are established to discuss the effect of simplified method for main girder on the accuracy of the result. The influence of seismic wave direction and wave-passage on seismic behaviors are analysed as well as the superstructure and arch ring interaction which is mostly related with the supported bearings and wind resistant springs. In the end, the application of cable-sliding aseismic devices is discussed to put forward a layout principle. The main conclusions include: (1) The seismic response isn't too distinctive with the simplified method of main girder. Generally speaking, the grillage method is recommended. (2) Under seismic input from different directions, arch foot is usually the mostly dangerous section. (3) Vertical wave input and horizontal wave-passage greatly influence the seismic responses of arch ring, significantly increasing that of midspan. (4) The superstructure interaction has an obvious impact on the seismic performance. Half-through arch bridges with long spandrel columns fixed has a less response than those with short ones fixed. And a large stiffness of wind resistant spring makes the the seismic responses of arch ring larger. (5) A good isolation effectiveness for half-through arch bridge can be achieved by a reasonable arrangement of CSFABs.

• Journal of Korean Association for Spatial Structures
• /
• v.11 no.4
• /
• pp.61-69
• /
• 2011

It is hard to predict the mechanical characteristics of discontinuous stone masonry structures with the use of by the static analysis method, because of irregularity of face stones and also due to randomness of backfill materials. Inversely, one can estimate the mechanical characteristics by comparing the natural frequencies between measured from the field tests and computed from the analytical models. The aim of this paper is to investigate the effectiveness and confidence of the computational modeling method of ancient stone arch bridges in Korea and to find the factors influencing their dynamic characteristics. The results revealed that the rigidity of spandrel walls and backfill materials are the most important factors influencing the natural frequencies of stone arch bridges, which are the critical for the stability of the stone arch structure.