• Earthquakes and Structures
• /
• v.15 no.1
• /
• pp.9-17
• /
• 2018

This paper provides recommendations for setting performance requirements for the seismic design of building structures in Hong Kong. Fundamental issues relating to the required level of structural safety will be addressed, which is then followed with a recommended seismic action model for structural design purposes in Hong Kong. The choice of suitable performance criteria of structures and the return period of the design seismic actions are first discussed. The development of the seismic hazard model for Hong Kong is then reviewed. The determination of the design response spectrum and the choice of design parameters for structures of different importance classes will also be presented.

• KCID journal
• /
• v.6 no.2
• /
• pp.37-46
• /
• 1999

This study is performed to select irrigation design year from 10-year return period 7-month(April to October) precipitation and compare reference crop evapotranspiration at 13 stations by REF-ET model. The three smallest 10-year return period 7-month(Apri

• Coupled systems mechanics
• /
• v.2 no.1
• /
• pp.111-126
• /
• 2013

The structural design requirements of an offshore platform subjected to wave induced forces and moments in the jacket can play a major role in the design of the offshore structures. For an economic and reliable design; good estimation of wave loadings are essential. A nonlinear response analysis of a fixed offshore platform under structural and wave loading is presented, the structure is discretized using the finite element method, wave plus current kinematics (velocity and acceleration fields) are generated using 5th order Stokes wave theory, the wave force acting on the member is calculated using Morison's equation. Hydrodynamic loading on horizontal and vertical tubular members and the dynamic response of fixed offshore structure together with the distribution of displacement, axial force and bending moment along the leg are investigated for regular and extreme conditions, where the structure should keep production capability in conditions of the 1-yr return period wave and must be able to survive the 100-yr return period storm conditions. The result of the study shows that the nonlinear response investigation is quite crucial for safe design and operation of offshore platform.

• Journal of Korean Society of Water and Wastewater
• /
• v.26 no.2
• /
• pp.321-329
• /
• 2012

In this study, statistical analysis under both stationary and non-stationary climate was conducted for rainfall data measured in Seoul. Generalised Extreme Value (GEV) distribution and Gumbel distribution were used for the analysis. Rainfall changes under the non-stationary climate were estimated by applying time variable (t) to location parameter (${\xi}$). Rainfall depths calculated in non-stationary climate increased by 1.1 to 6.2mm and 1.0 to 4.6mm for the GEV distribution and gumbel distribution respectively from those stationary forms. Changes in annual maximum rainfall were estimated with rate of change in the location parameter (${\xi}1{\cdot}t$), and temporal changes of return period were predicted. This was also available for re-evaluating the current sewer design return period. Design criteria of sewer system was newly suggested considering life expectance of the system as well as temporal changes in the return period.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.2
• /
• pp.153-160
• /
• 2011

Recently there are many long span cable supported bridges like Cable Stayed Bridge and Suspension Bridge already constructed or planned. Reconsidering of proper design wind load of long span bridge is required since the meteorological value based on the data only from 1960s to 1995 has been used when we estimate the wind load for designing long span bridges. In this paper, the research area was confined to western and southern coasts where many long span bridges have constructed. The method of moment and the least-squares method were used to estimate the expected wind speeds of 100 year's return period for girder bridges and for 200 year's return period for long span bridges based on the Gumbel's distribution. As the return-period wind speed on the land face was revised because of recent high speed velocity, the revised return-period wind speed is increased by 17%. Compatibility of return-period wind speed was also evaluated using RMS (Root Mean Square) error method. Aa a result of this paper, the least-squares method is more compatible than the method of moment in the case of western and southern coasts in Korea.

• Journal of Korean Society of Water and Wastewater
• /
• v.23 no.1
• /
• pp.47-55
• /
• 2009

Sewers are important national infrastructure and play an essential part by handling both wastewater and stormwater to minimise problems caused to human life and the environment. However, they can cause urban flooding when rainfall exceeds the system capacity. Sewer flooding is an unwelcome and increasingly frequent problem in many urban areas, and its frequency will increase over time with urbanisation and climate change. Under current standards, sewers are designed to drain stormwater generated by up to 10 year return period storms, but data suggests that many in practice have been experienced flooding with exceeding system capacity under increased storm events. A large number of studies has considered upgrading or increasing the design standard but there are still lack of information to propose a suitable return period with the corresponding system quantity to achieve. A methodology is required to suggest a proper level of standard within a suitable sewerage rehabilitation planning that can avoid the exceedance problem. This study aimed to develop a methodology to support effective sewer rehabilitation that could prevent urban flooding mainly resulted from the exceedance of existing storm sewer system capacity. Selected sewerage rehabilitation methods were examined under different storm return periods and compared to achieve the best value for money.

• Journal of Korean Society of Water and Wastewater
• /
• v.30 no.1
• /
• pp.41-49
• /
• 2016

In this study, rainfall characteristics with stationary and non-stationary perspectives were analyzed using generalized extreme value (GEV) distribution and Gumbel distribution models with rainfall data collected in major cities of Korea to reevaluate the return period of sewer flooding in those cities. As a result, the probable rainfall for GEV and Gumbel distribution in non-stationary state both increased with time(t), compared to the stationary probable rainfall. Considering the reliability of ${\xi}_1$, a variable reflecting the increase of storm events due to climate change, the reliability of the rainfall duration for Seoul, Daegu, and Gwangju in the GEV distribution was over 90%, indicating that the probability of rainfall increase was high. As for the Gumbel distribution, Wonju, Daegu, and Gwangju showed the higher reliability while Daejeon showed the lower reliability than the other cities. In addition, application of the maximum annual rainfall change rate (${\xi}_1{\cdot}t$) to the location parameter made possible the prediction of return period by time, therefore leading to the evaluation of design recurrence interval.

• KCID journal
• /
• v.19 no.1
• /
• pp.64-76
• /
• 2012

Recently, it has been increased disaster of crops and agricultural facilities with climate change such as regional storm, typhoon. However agricultural facilities have unsafe design criteria of improving drainage corresponding to this change. This study has analyzed the impact that inundation area and magnitude of drainage-facility is decided based on fixed- and unfixed-duration precipitation by applying revised design criteria of drainage for climate change. The result was shown that 1-day and 2-days rainfall for 20-years return period has increased about 11.4%, 4.4% respectively by changing fixed- to unfixed duration. And the increase rate of design flood was 15.0%. The result was also shown that Inundation area was enlarged by 6.6% as well as increased inundation duration under same basic condition in designed rainfall between fixed- and unfixed-duration. According to the analysis, it is necessary for pump capacity in unfixed-duration to be increased by 70% for same effect with fixed-duration. Therefore, when computing method of probability precipitation is changed from fixed one to unfixed-duration by applying revised design criteria, there seems to be improving effect in drainage design. Because 1440-minutes rainfall for 20-years return period with unfixed-duration is more effective than 1-day rainfall for 30-years return period with fixed-duration. By applying unfixed-duration rainfall, capacity of drainage facilities need to be expanded to achieve the same effects (Inundation depth & duration) with fixed-duration rainfall. Further study is required for considering each condition of climate, topography and drainage by applying revised design criteria.

• Steel and Composite Structures
• /
• v.18 no.1
• /
• pp.121-134
• /
• 2015

This paper is to investigate the potentials of the elastic seismic design of twisted high-rise steel diagrid frame buildings in the strong wind and moderate/low seismicity regions. First, the prototypes of high-rise steel diagrid frames with architectural plans that have a twist angle of 0 (regular-shaped), 1, and 2 degrees were designed to resist wind. Then, the effects of the twist angle on the estimated quantities and structural redundancies of the diagrid frames were examined. Second, the seismic performance of the wind-designed prototype buildings under a low seismicity was evaluated. The response spectrum analysis was conducted for the service level earthquake (SLE) having 43-year return period and the maximum considered earthquake (MCE) having 2475-year return period. The evaluation resulted that the twisted high-rise steel diagrid frames resisted the service level earthquake elastically and most of their diagrid members remained elastic even under the maximum considered earthquake.

• International Journal of High-Rise Buildings
• /
• v.1 no.3
• /
• pp.203-209
• /
• 2012

The purpose of this paper is to present the state of practice being used in the Philippines for the performance-based seismic design of reinforced concrete tall buildings. Initially, the overall methodology follows "An Alternative Procedure for Seismic Analysis and Design of Tall Buildings Located in the Los Angeles Region, 2008", which was developed by Los Angeles Tall Buildings Structural Design Council. After 2010, the design procedure follows "Tall Buildings Initiative, Guidelines for Performance-Based Seismic Design of Tall Buildings, 2010" developed by Pacific Earthquake Engineering Research Center (PEER). After the completion of preliminary design in accordance with code-based design procedures, the performance of the building is checked for serviceable behaviour for frequent earthquakes (50% probability of exceedance in 30 years, i.e,, with 43-year return period) and very low probability of collapse under extremely rare earthquakes (2% of probability of exceedance in 50 years, i.e., 2475-year return period). In the analysis, finite element models with various complexity and refinements are used in different types of analyses using, linear-static, multi-mode pushover, and nonlinear-dynamic analyses, as appropriate. Site-specific seismic input ground motions are used to check the level of performance under the potential hazard, which is likely to be experienced. Sample project conducted using performance-based seismic design procedures is also briefly presented.