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基于同震位移的隧道抗震设计及其工程应用
Seismic Design and Engineering Application ofTunnels Based on Coseismic Displacement
黄禄渊,王成虎,杨树新
- , 2019, DOI: 10.3969/j.issn.1000-0844.2019.01.029
Abstract: 首次在隧道抗震设计中考虑地震同震位移场，通过搜集历史地震破裂信息估计工程区地震位错，采用"分裂节点法"获得隧道周边的同震位移场，并联合拟静力隧道抗震设计方法，成功应用于某公路隧道。研究表明：基于同震位移的隧道抗震设计方法能够为我们估算未来可能的地震灾害提供有力的定量分析工具；当地层自振周期和基岩反应谱未知，可以利用同震位移场估算远场剪应变开展隧道拟静力抗震设计；例如对于云南某隧道，如果龙陵—澜沧断裂带发生地震，隧道南北两端强制位移约为6 cm。如果龙陵—瑞丽断裂发生地震，由于强制位移导致隧道南北部分出现反向运动，将会对隧道中部产生剪切作用，且隧道出现明显的横向和垂向差异运动。
In this work, the theory of the coseismic displacement field is first considered in the aseismic design of tunnels. We estimate earthquake dislocation in the engineering area by collecting historical earthquake rupture data. The coseismic displacement field around the tunnel is calculated through the splitting nodes method and applied in combination with the pseudostatic method in the aseismic design of a highway tunnel in Yunnan Province. Results show that the method based on coseismic displacement for the aseismic design of tunnels can provide a powerful quantitative analytical tool for the estimation of possible future earthquake disasters. If the natural vibration period and bedrock response spectrum are unknown, the coseismic displacement field can be used to estimate the far-field shear strain when conducting the quasistatic aseismic design of the tunnel. The forced displacement of the north and south segments of a tunnel in Yunnan is approximately 6 cm if earthquakes occur along the Longling-Lancang Fault Zone. If earthquakes occur along the Longling-Ruili Fault, forced displacement will cause reverse movement in the north and south parts of the tunnel. These movements will exert a pronounced shear effect on the middle of the tunnel, and lateral and vertical differential movements in the tunnel will intensify
A Comparison of Saudi Building Code with 1997 UBC for Provisions of Modal Response Spectrum Analysis Using a Real Building  [PDF]
Tariq M. Nahhas
Open Journal of Earthquake Research (OJER) , 2017, DOI: 10.4236/ojer.2017.62006
Abstract: The study uses an actual building to compare the modal response spectrum analysis results of Saudi Building Code (SBC) and the 1997 Uniform Building Code (UBC) used in Saudi Arabia before the introduction of SBC. A sample of four buildings with reported analysis of comparison between IBC and UBC is taken for confirming the comparison. Eight sample places from SBC map for Saudi Arabia together with two sample places of high seismic activity in USA were taken for the comparisons. The study used software package ETABS in this study for modeling and analysis. The results are dissimilar from the comparisons reported for test places of USA. It is concluded that at most places SBC base shear is higher for both ELFP and MRSA. However, the results cannot be generalized and considered always right. The same is factual for overturning moments. Consequently, we cannot report that SBC is more conservative than UBC for all scenarios.
Aeroacoustic Investigation of Trailing-Edge Finlets  [PDF]
Yehia Salama, Joana Rocha
Advances in Aerospace Science and Technology (AAST) , 2022, DOI: 10.4236/aast.2022.71001
Abstract: Wind tunnel testing and embedded large eddy simulations are employed to study the noise reduction of trailing-edge finlets on an airfoil. Trailing-edge finlets are shown to increase the distance between the highly energetic fluid particles and the sharp trailing edge. Experiments were conducted at different angles of attack. Wind tunnel measurements confirm that finlets reduce the broadband noise radiated by the airfoil. Results also reveal that the noise reduction of finlets is dependent on the airfoil angle of attack, and that the highest noise reduction is obtained at the largest angle of attack tested.
DYNAMIC INFLUENCE CAUSED BY CLOSE BLASTING ON PRIMARY AND SECONDARY SUPPORT SYSTEM IN TUNNEL
Zvonimir Ester,Mario Dobrilovi？,Darko Vrkljan
Rudarsko-Geolo？ko-Naftni Zbornik , 2003,
Abstract: At the construction site of the road tunnel Sv. Rok, the second, left tunnels tube is being constructed parallel to the unfinished right tunnel. The part of right tunnel tube is supported with primary support system according to NAMT, the second part is supported complete with concrete. Distance between axes of the tunnel tubes is approximately 35 m. Drifting of the left tube is being done by blasting. A potential problem of damaging the surrounding rock and support system was recognized. It is well known that the ground vibration particle velocity due to a blast is a measure of damage on the nearby construction. The three component seismographs were used to measure ground oscillation velocities in the right tunnel tube. Total of 30 measurements were executed and 720 values were processed (including all three component oscillation velocities). Maximum ground oscillation velocity recorded was 232.061 mm/s. This paper brings conclusion derived from monitoring data achieved at close proximity to the blasting area, damage level criteria for the rock mass and support system and discusses how these results could assist further development in the control of blasting technique.
DYNAMIC INFLUENCE CAUSED BY CLOSE BLASTING ON PRIMARY AND SECONDARY SUPPORT SYSTEM IN TUNNEL "SV. ROK"
Dobrilovi？, Mario,Ester, Zvonimir,Vrkljan, Darko
- , 2003,
Abstract: Sa？etak At the construction site of the road tunnel Sv. Rok, the second, left tunnels tube is being constructed parallel to the unfinished right tunnel. The part of right tunnel tube is supported with primary support system according to NAMT, the second part is supported complete with concrete. Distance between axes of the tunnel tubes is approximately 35 m. Drifting of the left tube is being done by blasting. A potential problem of damaging the surrounding rock and support system was recognized. It is well known that the ground vibration particle velocity due to a blast is a measure of damage on the nearby construction. The three component seismographs were used to measure ground oscillation velocities in the right tunnel tube. Total of 30 measurements were executed and 720 values were processed (including all three component oscillation velocities). Maximum ground oscillation velocity recorded was 232.061 mm/s. This paper brings conclusion derived from monitoring data achieved at close proximity to the blasting area, damage level criteria for the rock mass and support system and discusses how these results could assist further development in the control of blasting technique
Simplified Full Dynamic Analysis of a Railway Tunnel in Ethiopia  [PDF]
Henok Fikre Gebregziabher, Tequamework Assefa
World Journal of Engineering and Technology (WJET) , 2021, DOI: 10.4236/wjet.2021.93030
Abstract: This paper presents an effective means of analyzing the safety of a tunnel under dynamic loading in areas with seismic records. A particular case of the railway tunnel in the earthquake-prone regions of the escarpment seismic？zone of Ethiopia was the specific focus area of the research. Probabilistic seismic hazard analysis (PSHA) and deaggregation have been conducted to determine the design earthquake required as an input for the dynamic analysis. The PSHA performed by considering the operating design earthquake with conservative assumptions of the local geological features resulted in a peak ground acceleration of 0.36. Two pairs of design earthquake have been obtained from the deaggregation process, which were used to filter acceleration time histories for the selected design earthquake from the ground motion database of Pacific Earthquake Engineering Research Center. Finally, full dynamic analyses of the tunnel have been performed by applying the scaled acceleration time histories corresponding to the structure in the specific site. It was demonstrated how to prove the stability of the tunnel located in difficult ground conditions by performing plane strain analyses with the possible minimum computational efforts.
Seismic Evaluation and Retrofitting of Existing Hospital Building in the Sudan  [PDF]
A. E. Hassaballa, M. A. Ismaeil, Fathelrahman M. Adam
Open Journal of Civil Engineering (OJCE) , 2014, DOI: 10.4236/ojce.2014.42014
Abstract: Sudan is not free from earthquakes. It has experienced many earthquakes during the recent history, and the previous studies on this field demonstrated this argument. This paper focuses on the study of seismic performance of existing hospital buildings in Sudan. The paper focused on studying design of reinforced concrete columns of a hospital building considering two load cases; case one is the design load including combinations of dead, live and wind loads and case two includes dead, live and seismic loads. The building was designed according to the Regulation of Egyptian Society for Earthquake Engineering (ESEE), using the linear static method (equivalent static method). The analysis and design were performed using the SAP2000 version 14 software package. The design results obtained from the two cases of loading were compared observing that the design based on case one was unsafe to withstand the additional load came from earthquake, because the cross sections and area of steel for the most of building columns are under the required values that needed to resist the loads of case two. If the building is constructed according to the design using the loadings of case one, this situation needs remedy. This paper suggested two solutions for this problem based on strengthening the weak columns by inserting reinforced concrete shear walls in the direction of y axis affected by seismic load. Solution one suggests shear walls of length 2.5 m with different wall thicknesses (15 cm, 20 cm, 25 cm and 30 cm), whereas solution two suggests shear walls of length 4.5 m and 15 cm width. It was found that solution one solved the problem partially because some columns were still unsafe, but solution two solved the problem completely and all columns were safe.
Probability-Based Seismic Performance Evaluation for Buildings  [PDF]
Jeng-Hsiang Lin
World Journal of Engineering and Technology (WJET) , 2016, DOI: 10.4236/wjet.2016.43C002
Abstract:
Recent developments in earthquake engineering indicate that probabilistic seismic risk analysis (PSRA) is becoming increasingly useful for the evaluation of structural per-formance in accordance with building codes. In recent years, the field of seismic resis-tance design has been undergoing a critical shift in focus from strength to performance. However, current earthquake resistant design procedures do not relate building performance to probability. A lack of sufficient empirical data has highlighted gaps in this research. This study integrated results from the analysis of structural fragility and seismic hazard in Taiwan to perform PSRA to examine the effectiveness of building code in mitigating the risks associated with earthquakes. Factors taken into account included the effect of construction materials, building height, and building age. The results of this study show that the probability of exceeding damage associated with the CP level in buildings of light steel, pre-cast concrete, and masonry, exceeds 2%. These buildings fail to meet the performance objectives outlined in FEMA-273.
Assessment of Seismic Indirect Losses Based on Utility Curves  [PDF]
Jaime García-Pérez, Eric García-López
Open Journal of Civil Engineering (OJCE) , 2019, DOI: 10.4236/ojce.2019.93015
Abstract: In the process of quantifying optimum seismic design parameters, the losses implying the failure of the system must be assessed. Intangibles such as human lives may lie among indirect losses. In this paper, we propose a model to calculate the value of the investment that society should be willing to make for saving lives. In order to do this, we analyze both individual and social problems. However, special treatment is given to the individual problem where the value of the life of a human being is inferred by what the person should be willing to pay or willing to accept to reduce the risk of dying. Due to the use of utility curves in the calculation of this kind of intangible, we pay special attention to shape and requirement conditions of these curves. We also pay attention when personal impact and legacies or bequests are considered in utility curves. The results are shown through some applications, especially in the computation of optimum seismic design coefficients at a low seismicity site.
Seismic hazard versus design accelerograms
Horea SANDI
Constructii : Journal of Civil Engineering Research , 2012,
Abstract: The developments presented herewith arise from the legitimate wish and task of structural engineers of performing consistent analyses of risk and safety for works located in seismic regions. The paper adopts a probabilistic viewpoint, or philosophy. The starting point of this discussion is based on well – established approaches, while at the same time addressing specific research problems that could represent the task of the future, even if not an immediate one. The main topics are as follows: a brief view of (3-rd level) probabilistic safety and risk analysis, based on simplifying assumptions, which serves as a starting point for subsequent developments; a review of seismic action and hazard representation from two perspectives: ground motion during one event (advocating design accelerograms and stochastic models) and recurrence of successive events (considering, after the usual 1D approach, a generalized approach based on the consideration of a multi-dimensional space of characteristic action parameters); the development of a multi-dimensional stochastic model of ground motion (basically for a half-space consisting of successive horizontal homogeneous layers); a brief discussion of alternative possible objectives of engineering safety analyses.
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