46 research outputs found
An integrated micro-computer based qualitative and quantitative superstructure rating system for highway RCDG bridges
No full textAn integrated micro-computer based qualitative and quantitative superstructure rating system for highway bridges is developed. The purpose of this developed Windows-based software is to evaluate the qualitative condition of the components including the overall condition and to determine the strength of the bridge superstructure. A new approach is introduced in the qualitative condition rating. These improvements are the following: a criteria for quantifying and determining the condition of the various superstructure component, an importance factor for each component under various deterioration degree and a weighed average technique combining the rating of each component with its structural importance to determine the overall rating of the bridge. In the quantitative rating method, the Load and Resistance Factor Method is used instead of the operating and inventory rating.The software consists of three major modules: Bridge Inventory and Data module, qualitative and quantitative module and the on-line help module. These modules interact to perform an integrated superstructure bridge rating system
Managing the risks of a wind farm in typhoon-prone areas
No full textThe paper first ascertains the increase in buckling failure risk of a wind turbine due to typhoons. This condition necessitates a study of an efficient way of managing the risks in order to avoid financial ruin. Consequently the authors proposed methods for managing typhoons risk for existing and proposed wind farms. For the former, we explore the option of transferring the added risk to insurance. In this case, an optimum insurance premium is determined. For the latter, the risk is mitigated, by increasing the thickness of the tower. The optimum thickness is determined considering the projects\u27 net present value and the internal rate of return
Performance-based design of a wind turbine under typhoon and earthquake loads
No full textTwo extreme load levels, Levels 1 and 2, for typhoons and earthquakes were considered in the performance-based design of a wind turbine. The failure modes considered are tower buckling failure, anchor bolt pull-out and soil bearing capacity failure. For each load case the probabilities of failure for three damage states (minor, moderate and major) were analyzed. The cost of strengthening and the failure costs were also obtained. Finally an optimal investment cost is proposed which is important for wind farm owners for capital budgeting purposes. This value also corresponds to a target probability of failure of a wind turbine which can be used in the design of wind turbines in typhoon and earthquake-prone areas
Estimating the limit state exceeding probability of a deteriorating structure using the Kalman filter, extended Kalman filter, unscented Kalman filter and the sequential Monte Carlo simulation
No full textThis paper focuses on determining the limit state exceeding probability of a deteriorating model using optimal and sub-optimal Bayesian algorithms. Specifically the Kalman filter (for a linear system), extended Kalman filter, unscented Kalman filter and the sequential Monte Carlo simulation (for non-linear systems) are used to approximate the present state of a deteriorating system given measurements tainted with noise of the system output. In addition to the comprehensive discussion of the theory, numerical implementation and comparison of the results through numerical examples are shown
Reliability assessment of wooden trusses of a historical school
No full textRecords show that the National Structural Code of the Philippines (NSCP) wind load requirement increases over time. Increase wind velocity from stronger typhoon events translates to additional wind pressure. These changes pose a threat to existing historical structures such as Gabaldon schools which were designed and constructed more than a hundred years ago. The Department of Education (DepEd) continues its efforts in its conservation. Reliability assessment of wooden trusses is necessary to check if there is a need to retrofit to maintain its function and preserve its significance in the country\u27s history. In the analysis of the roof trusses affected directly by wind load, all loads are considered as constant except for the uniformly distributed wind load. These constant loads serve as the initial stresses acting within the truss members. Uniformly distributed wind load produces additional stress on top of the initial stress. Any changes in the amount of wind load constitute proportionally to changes in the stresses of truss members. A commercially available software makes it easier to identify corresponding stresses for several amounts of wind load. Using a spreadsheet, a simple graphical model and equation are generated expressing the relationship between wind velocities against axial force, shear force and bending moment. Mechanical properties of wood establish the limits of its strength in terms of wind velocity using the graphical model and equation obtained. The result reveals the limitation of each truss member in terms of wind velocity that even ordinary people can now easily perceived and understood. © Int. J. of GEOMATE
Structural strain estimates of a circular tunnel under seismic hazards
No full textThis paper presents an analytical approach to estimate 3-dimensional structural strains of a circular tunnel under an earthquake ground motion. Theoretical expressions including not only the axial and bending strains in the longitudinal direction but also the cross-sectional strains of a tunnel are developed in order to assess the current seismic design methods. Furthermore, the theoretical derivation of the soil and tunnel interaction effect can provide the analytical expression of soil spring modulus. Numerical results suggest that the cross-sectional tunnel strains are dependent upon the tunnel liner\u27s rigidity, so that the current design methods might overestimate the structural strains of the tunnel, especially having the liner\u27s hard rigidity for the Level 2 earthquake in Japan
Vulnerability assessment of Surigao Metro Water District under seismic hazard
No full textEarlier this year, Surigao Del Norte, a province in the Philippines experienced a 6.7 magnitude earthquake. The severe ground movement caused some of the buried pipelines to be pulled-out from their supports. This type of failure occurs when the ground strain during extreme seismic excitation exceeds the strain capacity of the buried pipe. The failure of the pipes resulted in the loss of water that was vital for post-earthquake recovery efforts. In this regard, there is a need to re-assess the vulnerability of the buried pipes of the water network. In this paper, a probabilistic seismic hazard analysis (PSHA) was employed to estimate the seismic hazard within the concession area. Past seismic data that can significantly affect the target structure is used for this purpose. The buried water lifeline system of Surigao Metro Water District (SMWD) was chosen as the target lifeline. An appropriate ground motion prediction equation (GMPE) was used to develop the uniform hazard response spectra for the site. To assess the vulnerability of the pipes three damage states were considered: major, moderate and minor. The probability of major, moderate and minor damage to each pipe was determined using Monte Carlo simulation. Subsequently, fragility curves were obtained
Optimal maintenance strategy for buried pipelines
No full textDecision strategy of inspection, repair and safety levels of buried pipelines under corrosive environment and third party incident risk is described. Pipe damages, which are caused by potential defect, corrosion, and third party accident, are classified into three typical damage models which include minor leakage, moderate leakage to cause eruption and major damage to develop a crack propagation. Risk assessment are made for a transmission pipeline system which is surrounded with various hazards spatially distributed along the pipeline route. The effect of risk reduction by the maintenance activities including periodic inspections and repair works are also taken into consideration, while the insurance premium approach is discussed to transfer the risk from the owner to the insurance company. Numerical calculations provide useful information on the effectiveness of the proposed four maintenance strategies
Stochastic capital budgeting approach to obtain the target probability of buckling failure of a wind turbine tower subjected to typhoons in the Philippines
No full textThe Manito geothermal livelihood project: Stimulating economic development in rural areas
No full textA drying plant and a 1.5 MW power plant was constructed in Manito, Albay, Philippines. The project was made possible through a government inter-agency joint undertaking. This project is the energy sector\u27s contribution to the government\u27s thrust to improve and accelerate the delivery of basic services, particularly to marginalized communities
