• Steel and Composite Structures
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• 제22권4호
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• pp.855-874
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• 2016

In this paper, it is aimed to evaluate the earthquake angle influence on the seismic performance of steel highway bridges. Upper-deck steel highway bridge, which has arch type load bearing system with a total length of 216 m, has been selected as an application and analyzed using finite element methods. The bridge is subjected to 1992 Erzincan earthquake ground motion components in nineteen directions whose values range between 0 to 90 degrees, with an increment of 5 degrees. The seismic weight is calculated using full dead load plus 30% of live load. The variation of maximum displacements in each directions and internal forces such as axial forces, shear forces and bending moments for bridge arch and deck are attained to determine the earthquake angle influence on the seismic performance. The results show that angle of seismic input motion considerably influences the response of the bridge. It is seen that maximum arch displacements are obtained at X, Y and Z direction for $0^{\circ}$, $65^{\circ}$ and $5^{\circ}$, respectively. The results are changed considerably with the different earthquake angle. The maximum differences are calculated as 57.06%, 114.4% and 55.71% for X, Y and Z directions, respectively. The maximum axial forces, shear forces and bending moments are obtained for bridge arch at $90^{\circ}$, $5^{\circ}$ and $0^{\circ}$, respectively. The maximum differences are calculated as 49.12%, 37.37% and 51.50%, respectively. The maximum shear forces and bending moments are obtained for bridge deck at $0^{\circ}$. The maximum differences are calculated as 49.67%, and 49.15%, respectively. It is seen from the study that the variation of earthquake angle effect the structural performance of highway bridges considerably. But, there is not any specific earthquake angle of incidence for each structures or members which increases the value of internal forces of all structural members together. Each member gets its maximum value of in a specific angle of incidence.

• Structural Engineering and Mechanics
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• 제63권5호
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• pp.647-657
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• 2017

To achieve this goal, two four-span concrete box-girder bridges with typical configurations of California highway bridges are selected as representative bridges: an integral abutment bridge and a seat-type abutment bridge. A detailed numerical model of the representative bridges is created in OpenSees to perform dynamic analyses. To examine the effect of earthquake incidence angle on the fragility of skewed bridges, the representative bridge models are modified with different skew angles. Dynamic analyses for all bridge models are performed for all earthquake incidence angles examined. Simulated results are used to develop demand models and component and system fragility curves for the skewed bridges. The fragility characteristics are compared with regard to earthquake incidence angle. The results suggest that the earthquake incidence angle more significantly affects the seismic demand and fragilities of the integral abutment bridge than the skewed abutment bridge. Finally, a recommendation to account for the randomness due to the ground motion directionality in the fragility assessment is made in the absence of the predetermined earthquake incidence angle.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 1998년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Spring 1998
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• pp.113-119
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• 1998

This study is focused on evaluation of the structural behavior of skewed bridge during earthquake. The variation of natural frequencies and the lateral forces at pier shoes by the skewness and the rotational effect about vertical axis of skewed bridge due to seismic activity are analytically evaluated and identified through case studies. For this purpose, the composite steel girder highway bridges are selected as case study models. The seismic analyses by response spectrum method and time history method are performed for the selected models. It has been recognized that the frequency of longitudinal model increased as the skew angle decreased, while the lateral mode frequency showed the opposite trends. When the skew angle decreased, longitudina seismic forces of the bridge at the pier were increased but decreased in transverse direction. And it also has been found that the skewed bridges of the case study models showed the rotational behavior about vertical axis due to motion of San Fernando earthquake at Pacoima Dam.

• Earthquakes and Structures
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• 제13권1호
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• pp.39-50
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• 2017

Displacement response and corresponding maximum response energy of structures are key parameters to assess the dynamic effect or even more destructive structural damage of the structures. By employing them, this research has compared the structural responses of jacket supported offshore wind turbine (OWT) subjected to seismic excitations apprehending earthquake incidence, when (a) soil-structure interaction (SSI) has been ignored and (b) SSI has been considered. The effect of earthquakes under arbitrary angle of excitation on the OWT has been investigated by means of the energy based wavelet transformation method. Displacement based fragility analysis is then utilized to convey the probability of exceedance of the OWT at different soil site conditions. The results show that the uncertainty arises due to multi-component seismic excitations along with the diminution trend of shear wave velocity of soil and it tends to reduce the efficiency of the OWT to stand against the ground motions.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2006년도 학술발표회 논문집
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• pp.351-357
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• 2006

In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) subjected to earthquake loading was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam during earthquake loading with this input parameter. From the sensitivity analysis, it was found that the crest displacement of CFR type dam subjected to dynamic loading was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the extent of effect of shear modulus on the displacement at the crest of CFRD due to dynamic loading decreased as maximum amplitude of input acceleration increased.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.321-328
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• 2003

The objective of this study is to investigate the seismic response of high-rise RC bearing-wall structures with irregularity. For this purpose, three 1:12 scale 17-story reinforced concrete model structures were constructed according to the similitude law, in which the upper 15 stories have a bearing-wall system while the lower 2-story frames have three different layouts of the plan : The first one is a moment-resisting frame system, the second has a infilled shear wall with symmetric plan and the third has a infilled shear wall with eccentricity, Then, these models were subjected to a series of earthquake excitations. The test results show the followings: 1) the existence of shear wall reduced greatly shear deformation at the piloti frame, but has almost the negligible effect on the reduction of the overturning-moment angle, 2) the frame with shear wall resists most of overturning moment in severe earthquake, 3) the torsional behavior is almost independent of the translational, 4) the absorbed energy due to the overturning deformation has the largest portion in the total absorbed energy.

• Earthquakes and Structures
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• 제8권5호
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• pp.1127-1146
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• 2015

The excitation angle or angle of incidence is the angle in which the horizontal seismic components are applied with respect to the principal structural axes during a time history analysis. In this study, numerical simulations and parametric studies are performed for the investigation of the effect of the angle of seismic incidence on the response of adjacent buildings, which may experience structural pounding during strong earthquakes due to insufficient or no separation distance between them. A specially developed software application has been used that implements a simple and efficient methodology, according to which buildings are modelled in three dimensions and potential impacts are simulated using a novel impact model that takes into account the arbitrary location of impacts and the geometry at the point of impact. Two typical multi-storey buildings and a set of earthquake records have been used in the performed analyses. The results of the conducted parametric studies reveal that it is very important to consider the arbitrary direction of the ground motion with respect to the structural axes of the simulated buildings, especially during pounding, since, in many cases, the detrimental effects of pounding become more pronounced for an excitation angle different from the commonly examined 0 or 90 degrees.

• Geomechanics and Engineering
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• 제29권6호
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• pp.599-614
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• 2022

In this study, the reliability analysis of internal and external stabilities of Reinforced Soil Walls (RSWs) under static and seismic loads are investigated so that it can help the geotechnical engineers to perform the design more realistically. The effect of various variables such as angle of internal soil friction, soil specific gravity, tensile strength of the reinforcements, base friction, surcharge load and finally horizontal earthquake acceleration are examined assuming the variables uncertainties. Also, the correlation coefficient impact between variables, sensitivity analysis, mean change, coefficient of variation and type of probability distribution function were evaluated. In this research, external stability (sliding, overturning and bearing capacity) and internal stability (tensile rupture and pull out) in both static and seismic conditions were investigated. Results of this study indicated sliding as the predominant failure mode in the external stability and reinforcing rupture in the internal stability. First-Order Reliability Method (FORM) are applied to estimate the reliability index (or failure probability) and results are validated using the Monte Carlo Simulation (MCS) method. The results showed among all variables, the internal friction angle and horizontal earthquake acceleration have dominant impact on the both reinforced soil wall internal and external stabilities limit states. Also, the type of probability distribution function affects the reliability index significantly and coefficient of variation of internal friction angle has the greatest influence in the static and seismic limits states compared to the other variables.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.407-414
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• 2001

The severe shortage of the available sites in the highly developed downtown area in Korea necessitates the construction of high-rise buildings which meet the need of residence and commercial activity simultaneously. The objective of this study is to investigate the seismic performance of this type of building structures. For this purpose, two 1 :12 scale 17-story reinforced concrete model structures were constructed according to the similitude law, in which the upper 15 stories have a bearing-wall system while the lower 2-story frames have two different layouts of the plan The one is a moment-resisting frame system and the other is a moment-resisting frame system with a infilled shear wall. Then, this model was subjected to a series of earthquake excitations. The test results show that the existence of shear wall reduced the shear deformation at the piloti frame, but has almost the negligible effect on the reduction of the overturning-moment angle.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 추계 학술발표회논문집
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• pp.36-45
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• 2003

Sensitivity analyses for several seismic source models were studied. For the area sources, the hazard is steeply decreasing with the source-to-site distance. Hazard is decreasing when the area of the source is increasing with fixed annual rate. For the fault sources, the fault length, distance from a site and dip angle of near fault show very sensitive effect to seismic hazard. But the various magnitude-rupture length relationships show effect to seismic hazard slightly. For the fault source with small magnitude, the exponential model is preferred rather than the characteristic model to the magnitude-recurrence law.