Load Ratings for Standard Bridges, HR-239 Phase IV, 2008

In this report, sixteen secondary and primary bridge standards for two types of bridges are rated for AASHTO HS20-44 vehicle configuration utilizing Load Factor methodology. The ratings apply only to those bridges which: (1) are built according to the applicable bridge standard plans, (2) have no structural deterioration or damage, and (3) have no added wearing surface in excess of one-half inch integral wearing surface.

Short-Term Load Forecast Of A Low Loadfactor Power System For Optimization Of Merit Order Dispatch Using Adaptive Learning Algorithm

Short term load forecasting is one of the key inputs to optimize the management of power system. Almost 60-65% of revenue expenditure of a distribution company is against power purchase. Cost of power depends on source of power. Hence any optimization strategy involves optimization in scheduling power from various sources. As the scheduling involves many technical and commercial considerations and constraints, the efficiency in scheduling depends on the accuracy of load forecast. Load forecasting is a topic much visited in research world and a number of papers using different techniques are already presented. The accuracy of forecast for the purpose of merit order dispatch decisions depends on the extent of the permissible variation in generation limits. For a system with low load factor, the peak and the off peak trough are prominent and the forecast should be able to identify these points to more accuracy rather than minimizing the error in the energy content. In this paper an attempt is made to apply Artificial Neural Network (ANN) with supervised learning based approach to make short term load forecasting for a power system with comparatively low load factor. Such power systems are usual in tropical areas with concentrated rainy season for a considerable period of the year

Investigation of the relationship between load and loss factors for a Brazilian electric utility

With the considerable increase of the losses in electric utilities of developing countries, such as Brazil, there is an investigation for loss calculation methodologies, considering both technical (inherent of the system) and non-technical (usually associated to the electricity theft) losses. In general, all distribution networks know the load factor, obtained by measuring parameters directly from the network. However, the loss factor, important for the energy loss cost calculation, can only be obtained in a laborious way. Consequently, several formulas have been developed for obtaining the loss factor. Generally, it is used the expression that relates both factors, through the use of a coefficient k. Last reviews introduce a range of factor k within 0.04 - 0.30. In this work, an analysis with real life load curves is presented, determining new values for the coefficient k in a Brazilian electric utility. © 2006 IEEE.

A statistical analysis of loss factor to determine the energy losses

Given that the total amount of losses in a distribution system is known, with a reliable methodology for the technical loss calculation, the non-technical losses can be obtained by subtraction. A usual method of calculation technical losses in the electric utilities uses two important factors: load factor and the loss factor. The load factor is usually obtained with energy and demand measurements, whereas, to compute the loss factor it is necessary the learning of demand and energy loss, which are not, in general, prone of direct measurements. In this work, a statistical analysis of this relationship using the curves of a sampling of consumers in a specific company is presented. These curves will be summarized in different bands of coefficient k. Then, it will be possible determine where each group of consumer has its major concentration of points. ©2008 IEEE.

Analysis of efficiency and rationality in a sugar-alcohol mill using hyperboloid a-load and potency

Brazil is the world's largest producer of sugar cane and which in the state of São Paulo concentrate the greatest amount of sugar cane field of the country. The sugar-alcohol sector has the capacity to produce sufficient thermal and electrical energy to be used in their process of production and commercialize of surplus in electricity distribution network. Therefore it is necessary to evaluate the energy efficiency and rationality within the mill. Accordingly this research proposed analyze the sugar-alcohol mill's sectors globally and individually, located in the west center of the São Paulo state, using the valuation methodology employed by the Agência Nacional de Energia Elétrica (ANEEL) in the industries that do not have systems of cogeneration. In this analysis, the hyperboloids of load and potency were applied based on the indexes of potency factor and load factor that allow estimate the efficiency and rationality. © 2013 IEEE.

Investigation of the Impact of Dual-Lane Axle Spacing on Lateral Load Distribution, 2016

The spacing of adjacent wheel lines of dual-lane loads induces different lateral live load distributions on bridges, which cannot be determined using the current American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) or Load Factor Design (LFD) equations for vehicles with standard axle configurations. Current Iowa law requires dual-lane loads to meet a five-foot requirement, the adequacy of which needs to be verified. To improve the state policy and AASHTO code specifications, it is necessary to understand the actual effects of wheel-line spacing on lateral load distribution. The main objective of this research was to investigate the impact of the wheel-line spacing of dual-lane loads on the lateral load distribution on bridges. To achieve this objective, a numerical evaluation using two-dimensional linear elastic finite element (FE) models was performed. For simulation purposes, 20 prestressed-concrete bridges, 20 steel bridges, and 20 slab bridges were randomly sampled from the Iowa bridge database. Based on the FE results, the load distribution factors (LDFs) of the concrete and steel bridges and the equivalent lengths of the slab bridges were derived. To investigate the variations of LDFs, a total of 22 types of single-axle four-wheel-line dual-lane loads were taken into account with configurations consisting of combinations of various interior and exterior wheel-line spacing. The corresponding moment and shear LDFs and equivalent widths were also derived using the AASHTO equations and the adequacy of the Iowa DOT five-foot requirement was evaluated. Finally, the axle weight limits per lane for different dual-lane load types were further calculated and recommended to complement the current Iowa Department of Transportation (DOT) policy and AASHTO code specifications.

Survey and dynamic behaviour of the Our Lady of Conception Church, Portugal

The Our Lady of Conception church is located in village of Monforte (Portugal) and is not in use nowadays. The church presents structural damage and, consequently, a study was carried out. The study involved the survey of the damage, dynamic identification tests under ambient vibration and the numerical analysis. The church is constituted by the central nave, the chancel, the sacristy and the corridor to access the pulpit. The masonry walls present different thickness, namely 0.65 m in the chancel, 0.70 m in the sacristy, 0.92 in the central nave and 0.65 m in the corridor. The masonry walls present 8 buttresses with different dimensions. The total longitudinal and transversal dimensions of the church are equal to 21.10 m and 14.26 m, respectively. The survey of the damage showed that, in general, the masonry walls are in good conditions, with exception of the transversal walls of the nave, which present severe cracks. The arches of the vault presents also severe cracks along the central nave. As consequence, the infiltrations have increased the degradation of the vault and paintings. Furthermore, the foundations present settlements in the Southwest direction. The dynamic identification test were carried out under the action of ambient excitation of the wind and using 12 piezoelectric accelerometers of high sensitivity. The dynamic identification tests allowed to estimate the dynamic properties of the church, namely frequencies, mode shapes and damping ratios. A FEM numerical model was prepared and calibrated, based on the first four experimental modes estimated in the dynamic identification tests. The average error between the experimental and numerical frequencies of the first four modes is equal to 5%. After calibration of the numerical model, pushover analyses with a load pattern proportional to the mass, in the transversal and longitudinal direction of the church, were performed. The results of the analysis numerical allow to conclude that the most vulnerable direction of the church is in the transversal one and the maximum load factor is equal to 0.35.

Estudo da cabeceira da Sé do Porto

Dissertação de mestrado integrado em Engenharia Civil

Kuulakekoreaktorin sähköntuotantokustannusten arviointi

Tässä työssä selvitettiin heliumjäähdytteisellä kuulakekoreaktorilla tuotetun sähkön hinnan muodostumista. Saatuja tuloksia vertailtiin hiilidioksidin erotuksen savukaasuista mahdollistavilla laitteilla varustettuihin hiili- ja maakaasuvoimalaitoksiin sekä kevytvesitekniikalla toteutettuun ydinvoimalaan. Työssä käytiin lyhyesti läpi kuulakekoreaktorin tekniikkaa ja mahdollisia sovelluskohteita, joissa voidaan käyttää hyväksi reaktorin jäähdytteen korkeaa lämpötilaa. Kuulakekoreaktorin kustannustietoja arvioitiin eri lähteissä esitettyjen lukujen perusteella. Ominaisinvestointikustannukseksi saatiin 1722 €/kWe. Sähköntuotannon polttoainekustannukseksi laskettiin 5,4 €/MWh ja käyttö- ja kunnossapito-kustannuksina käytettiin 7 €/MWh. Laitoksen sähköntuotantokustannusten laskenta suoritettiin annuiteettimenetelmällä käyttäen 5 % reaalikorkoa ja 40 vuoden taloudellista pitoaikaa sekä 90 % käyttökerrointa. Laskuissa käytettiin vuoden 2002 hintatasoa. Laskelmien perusteella kuulakekoreaktorin sähköntuotantokustannukseksi saatiin 25,1 €/MWh. Tämän todettiin olevan samalla tasolla kuin kevytvesireaktorilla tuotetun sähkön hinta. Hiilidioksidin erotuslaitteilla varustetun hiilivoimalaitoksen sähköntuotantokustannukseksi saatiin 44,0 €/MWh ja maakaasukombivoimalaitoksen 36,3 €/MWh.

Sähkön tuotantokustannusvertailu

Työssä vertaillaan eri sähköntuotantovaihtoehtojen taloudellista kannattavuutta. Kannattavuusvertailu suoritetaan pelkkää sähköä tuottaville voimalaitoksille. Sähkön ja lämmön yhteistuotannon lisärakentaminen tulee kattamaan tietyn osuuden lähitulevaisuuden sähkön hankinnan vajeesta, mutta sen lisäksi tarvitaan myös uutta lauhdetuotantokapasiteettia. Tutkittavat voimalaitostyypit ovat: ydinvoimalaitos, maakaasukombilauhdevoimalaitos, kivihiililauhdevoimalaitos, turvelauhdevoimalaitos, puulauhdevoimalaitos ja tuulivoimala. Kannattavuustarkastelu suoritetaan annuiteettimenetelmällä käyttäen 5 % reaalikorkoa ja tammikuun 2008 hintatasoa. Laskelmien perusteella 8000 tunnin huipunkäyttöajalla ydinsähkön tuotantokustannus olisi 35,0 € /MWh, kaasusähkön 59,2 €/MWh ja hiilisähkön 64,4 €/MWh, kun hiilidioksidipäästöoikeuden hintana käytetään 23 €/t. Ilman päästökauppaa kaasusähkön hinta on 51,2 €/MWh ja hiilisähkön 45,7 €/MWh ydinsähkön hinnan pysyessä ennallaan. Herkkyystarkastelun tulosten perusteella ydinvoiman kilpailukyky korostuu muihin tarkasteltuihin tuotantomuotoihin verrattuna. Ydinpolttoaineen suurellakaan hinnan muutoksella ei ole merkittävää vaikutusta ydinsähkön tuotantokustannukseen, kun taas maakaasusähkö on erittäin riippuvainen polttoaineen hinnasta. Myös päästöoikeuden hinnan kasvu lisää merkittävästi ydinvoiman kilpailukykyä kaasu- ja hiilisähköön verrattuna. Ydinvoimainvestoinnin kannattavuutta ja takaisinmaksua tarkastellaan myös yksinään siten, että investoinnilla saavutettavien tuottojen laskennassa käytetään useita eri sähkön markkinahintoja. Investoinnin kannattavuus on erittäin hyvä, kun sähkön markkinahinta on 50 €/MWh tai suurempi.

Comparison of electricity generation costs

The economical competitiveness of various power plant alternatives is compared. The comparison comprises merely electricity producing power plants. Combined heat and power (CHP) producing power will cover part of the future power deficit in Finland, but also condensing power plants for base load production will be needed. The following types of power plants are studied: nuclear power plant, combined cycle gas turbine plant, coal-fired condensing power plant, peat-fired condensing power plant, wood-fired condensing power plant and wind power plant. The calculations are carried out by using the annuity method with a real interest rate of 5 % per annum and with a fixed price level as of January 2008. With the annual peak load utilization time of 8000 hours (corresponding to a load factor of 91,3 %) the production costs would be for nuclear electricity 35,0 €/MWh, for gas based electricity 59,2 €/MWh and for coal based electricity 64,4 €/MWh, when using a price of 23 €/tonCO2 for the carbon dioxide emission trading. Without emission trading the production cost of gas electricity is 51,2 €/MWh and that of coal electricity 45,7 €/MWh and nuclear remains the same (35,0 €/MWh) In order to study the impact of changes in the input data, a sensitivity analysis has been carried out. It reveals that the advantage of the nuclear power is quite clear. E.g. the nuclear electricity is rather insensitive to the changes of nuclear fuel price, whereas for natural gas alternative the rising trend of gas price causes the greatest risk. Furthermore, increase of emission trading price improves the competitiveness of the nuclear alternative. The competitiveness and payback of the nuclear power investment is studied also as such by using various electricity market prices for determining the revenues generated by the investment. The profitability of the investment is excellent, if the market price of electricity is 50 €/MWh or more.

Operointialueen huomioiminen risteilylaivan sähkötaseessa

Kiristyvät päästörajoitukset ja muuttuvat säädökset ovat muokanneet laivanrakennusalaa energiatehokkaampaan ja ympäristöystävällisempään suuntaan. Energiatehokkuutta tutkitaan yksittäisistä laiteratkaisuista laivan operointitasolle asti. Tämä työ on tehty osana STX Finland Oy:n laivojen energiatehokkuuden tutkimusta. Työn tarkoituksena oli uudistaa laivojen sähkötaseen laskennassa käytettyjä kuormitustaulukoita ja kehittää operointialueen vaikutuksia huomioiva laskentamenetelmä. Uudistuksen taustalla oli tieto operointialueiden ympäristöolosuhteiden vaikutuksista sähkönkulutukseen ja työn tarkoituksena oli mahdollistaa suunnittelun myöhäisemmässä vaiheessa tehtävä operointialuekohtainen sähkönkulutustarkastelu. Sähkötaseen laskenta haluttiin vastaamaan enemmän todellista sähkönkulutusta. Aikaisemmin käytetystä mitoitusperusteisesta laskennasta haluttiin siirtyä todellisempien kuormien arviointiin laitteiden ja muuntajien turhan ylimitoituksen poistamiseksi. Kuormitustaulukoiden toimintaa yksinkertaistettiin ja taulukoista tehtiin helpommin mukautuvia, jotta erilaisten operointitilanteiden vertailu olisi mahdollista. Perinteisen taselaskennan rinnalle kehitettiin operointialueiden vaikutuksia huomioivat laskentataulukot. Uudet taulukot huomioivat komponenttien sähkönkulutuksen prosentuaalisen muutoksen operointialueittain sekä yksilöllisesti että kulutusryhmittäin. Laskentataulukoiden yhteyteen tehtiin kuvaajat havainnollistamaan alueittaisia kulutuseroja.

Sähkön tuotantokustannusvertailu

Työssä vertaillaan eri sähköntuotantovaihtoehtojen taloudellista kannattavuutta. Kannattavuusvertailu suoritetaan pelkkää sähköä tuottaville voimalaitoksille. Raportti on jatkoa aikaisemmille tutkimuksille, joista viimeisin julkaistiin 2008. Tutkittavat voimalaitostyypit ovat: ydinvoimalaitos, maakaasukombilauhdevoimalaitos, kivihiililauhdevoimalaitos, turvelauhdevoimalaitos, puulauhdevoimalaitos, tuulivoimala ja uutena aurinkovoimala. Kannattavuustarkastelu suoritetaan annuiteettimenetelmällä käyttäen 5 % reaalikorkoa ja maaliskuun 2012 hintatasoa. Laskelmien perusteella 8000 tunnin huipunkäyttöajalla ydinsähkön tuotantokustannus, kun laitos rakennetaan olemassaolevalle tontille olisi 43,7 €/MWh, täysin uuden ydinvoimalaitoksen 57,9 €/MWh, kaasusähkön 75,4 €/MWh, turvelauhteen 75,4 €/MWh ja hiilisähkön hiilidioksidin talteenotolla 64,4 €/MWh, kun hiilidioksidipäästöoikeuden hintana käytetään 23 €/t. Vastaavasti uusiutuvista puupolttoainelauhdesähkön tuotantokustannus olisi 70,2 €/MWh kun taas 2200 tunnin huipunkäyttöajalla maalla sijaitsevan tuulivoimalaitoksen sähkön tuotantokustannus 52,7 €/MWh ja merellä sijaitsevan tuulivoimalaitoksen 76,8 €/MWh. Erillistarkastelussa arvioitiin suurien keskittävää teknologiaa käyttävän aurinko-voimalaitoksen tuotantokustannuksen ylittävän 100 €/MWh ollen todennäköisesti lähempänä 150 €/MWh. Arvio piensähkön tuotantokustannuksista aurinkosähköisillä paneeleilla vaihtelee 90 – 130 €/MWh. Merkittävin kustannussäästö syntyy, jos aurinkosähköpaketteja voidaan tarjota kuluttajalle kokonaistoimituksena avaimet käteen. Aurinkosähkön tuottaminen kotikeräimillä näyttääkin olevan vaiheessa, jossa se on selkeästi pienkäyttäjälle edullista mikäli sijoitettava pääoma 6000 – 18000 € ei vaadi ulkopuolista rahoitusta.

Finite Element Analysis of Warship Structures

Warships are generally sleek, slender with V shaped sections and block coefficient below 0.5, compared to fuller forms and higher values for commercial ships. They normally operate in the higher Froude number regime, and the hydrodynamic design is primarily aimed at achieving higher speeds with the minimum power. Therefore the structural design and analysis methods are different from those for commercial ships. Certain design guidelines have been given in documents like Naval Engineering Standards and one of the new developments in this regard is the introduction of classification society rules for the design of warships.The marine environment imposes subjective and objective uncertainties on ship structure. The uncertainties in loads, material properties etc.,. make reliable predictions of ship structural response a difficult task. Strength, stiffness and durability criteria for warship structures can be established by investigations on elastic analysis, ultimate strength analysis and reliability analysis. For analysis of complicated warship structures, special means and valid approximations are required.Preliminary structural design of a frigate size ship has been carried out . A finite element model of the hold model, representative of the complexities in the geometric configuration has been created using the finite element software NISA. Two other models representing the geometry to a limited extent also have been created —- one with two transverse frames and the attached plating alongwith the longitudinal members and the other representing the plating and longitudinal stiffeners between two transverse frames. Linear static analysis of the three models have been carried out and each one with three different boundary conditions. The structural responses have been checked for deflections and stresses against the permissible values. The structure has been found adequate in all the cases. The stresses and deflections predicted by the frame model are comparable with those of the hold model. But no such comparison has been realized for the interstiffener plating model with the other two models.Progressive collapse analyses of the models have been conducted for the three boundary conditions, considering geometric nonlinearity and then combined geometric and material nonlinearity for the hold and the frame models. von Mises — lllyushin yield criteria with elastic-perfectly plastic stress-strain curve has been chosen. ln each case, P-Delta curves have been generated and the ultimate load causing failure (ultimate load factor) has been identified as a multiple of the design load specified by NES.Reliability analysis of the hull module under combined geometric and material nonlinearities have been conducted. The Young's Modulus and the shell thickness have been chosen as the variables. Randomly generated values have been used in the analysis. First Order Second Moment has been used to predict the reliability index and thereafter, the probability of failure. The values have been compared against standard values published in literature.