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Book Load Distribution and Rating Assessment of Variable Depth Continuous Slab Bridges

Download or read book Load Distribution and Rating Assessment of Variable Depth Continuous Slab Bridges written by Ahmadudin Burhani and published by . This book was released on 2021 with total page 261 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many in-service reinforced concrete slab bridges in the United States have thicknesses that change along the span, leading to variation in flexural rigidity. Despite being commonly used, determining their live load carrying capacity has remained routinely uncertain. The variabilities are often ignored, and typical programs, such as AASHTOWare Bridge Rating (BrR), are used to assess such bridges’ structural capacity. In turn, this resulted in the entire analysis being subjected to erroneous results. Moreover, many of these structures are susceptible to weight restrictions due to shortened termination of reinforcements used in the negative moment regions. It is not always clear to which degree the reinforcement length affects such bridges’ structural capacity. It is also uncertain whether other parameters, such as bridge geometry, play role in improving the structural capacity. The objective of this study was to use experimental results and three-dimensional finite element simulations to assess the structural capacity of LOG-47-1184, a concrete highway bridge in Ohio that has four lanes and three consecutive spans of varying thickness and is subject to load restrictions. The study further provides an appropriate development length that satisfies different levels of section variability. The effect of the bridge’s geometry on the reinforcement was investigated. The experimental response of the bridge was determined, and results were used to calculate sets of load rating factors (LRFs) and to validate a three-dimensional finite element model (FEM). A detailed rating analysis found LRFs using the FEM were greater than those from Midas Civil, which in turn were greater than those from the legacy BrR program used by the Ohio Department of Transportation. The ratios of the BrR LRFs to the other procedure were generally constant across multiple test truck load configurations, with less than 4% variation for BrR/Midas Civil and about 25% for BrR/FEM. The LRFs from the FEM satisfied the operating checks and all LRFs exceeded one; therefore, no load restriction posting was required for the bridge. As a result, this study suggests that similar bridges that are susceptible to load restrictions based on the BrR outputs might have adequate structural capacity. Subsequently, it was found that the haunching increased force effects over intermediate supports, which in turn required longer development length. A total reasonable length was determined to be 4L/7, which can be extended on either side of intermediate supports. The FEM simulations underestimated AASHTO LRFD requirements by an average of 40%. Under HL-93 load configurations and using the LRFR approach, all LRFs exceeded one and satisfied the operating rating checks. The LRFs improved by 30% when the skew angle exceeded 15o as compared with 0o and reached 61% with the skew angle of 30o.

Book Load Distribution in Concrete Bridge Decks

Download or read book Load Distribution in Concrete Bridge Decks written by Anthony Ralph Cusens and published by . This book was released on 1974 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Finite Element Analysis of Concrete Solid Slab Bridges

Download or read book Finite Element Analysis of Concrete Solid Slab Bridges written by Rami Ibrahim Jabakhanji and published by . This book was released on 1999 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report presents an investigation of the behavior of simply supported, multi-lane, reinforced concrete solid slab bridges using the finite element method. Solid slab bridges have a behavior pattern that falls between one-way slab behavior and two-way slab behavior. Geometric parameters such as: span length, thickness of slab, number of lanes, presence of shoulders, and the location of trucks, affect the behavioral pattern of solid slab bridges. Therefore, this study will investigate the effect of these factors by analyzing one-lane, two-lane, three-lane, and four-lane bridges, with or without shoulders, each having four different span lengths. Bridges were fully loaded (one AASHTO HS20 truck in each lane). Loads were either centered in every lane, or located towards one edge of the slab. In addition, all the slab bridges with shoulders were over-loaded by assuming a disabled truck on one edge of the bridge in combination with the other design trucks stationed side by side; this combination produces the worst loading conditions on the bridge. Design trucks were positioned in the longitudinal direction in order to produce the maximum positive bending moment.--The finite element method is proposed to analyze the solid slab bridges by using the structural analysis program SAP90. The research focussed on evaluating the maximum lateral bending moment distribution over the critical cross-section of the bridges. The results of this study were used to assess the design approach currently employed by the American Association of State Highway and Transportation Officials (AASHTO) " Standard Specifications for Highway Bridges (1996)."

Book Improved Load Rating of Reinforced Concrete Slab Bridges

Download or read book Improved Load Rating of Reinforced Concrete Slab Bridges written by David Villegas Jãuregui and published by . This book was released on 2007 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Influence of Skewness on Reinforced Concrete Slab Bridges

Download or read book Influence of Skewness on Reinforced Concrete Slab Bridges written by Carol Shukri Menassa and published by . This book was released on 2002 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: The thesis investigates the effect of skewness on reinforced concrete solid slab bridges. This study considers bridge decks with various angles of skewness, and live load distribution from truck loading on the solid slab is determined. Simple multi-lane bridges are analyzed for a variety of span lengths and slab widths. The loading consists of AASHTO HS-20 design truck, which is so positioned laterally and longitudinally to produce maximum moments in the slab. The analysis is performed using the finite element method and a proper mesh is selected to account for the skewness of the bridge slab. Finally, the behavior of the bridges analyzed is assessed with design procedure currently in use. The American Association of State Highway and Transportation Officials (AASHTO), "Standard Specifications for Highway Bridges, 1996". Also, a comparison between straight and skewed bridges is conducted.

Book Masters Theses in the Pure and Applied Sciences

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer. This book was released on 1990-01-31 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1 957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 32 (thesis year 1987) a total of 12,483 theses titles from 22 Canadian and 176 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 32 reports theses submitted in 1987, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.

Book Load Reduction in Multi lane Concrete Slab Bridges

Download or read book Load Reduction in Multi lane Concrete Slab Bridges written by Fatima Mohamad El Meski and published by . This book was released on 2007 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt: This current research presents the finite-element results of a study investigati ng the effect of multi-presence of design vehicles on three- and four-lane concr ete slab highway bridges. Typical one-span, simply supported, two spans, multil ane (three and four lanes), reinforced concrete slab bridges are considered. The finite-element method is used to investigate the effect of span length and slab width, and to calculate the wheel load distribution on the bridge slab at the c ritical section. Live load reduction factors are proposed by the American Association for State H ighway and Transportation Officials (AASHTO) specifications, due to the improbab ility of maximum coincident loading. These live-load reduction factors are impo sed to account for the probability of having all lanes loaded at the same time a nd at locations along the bridge deck producing the maximum bending moment in an element of a bridge superstructure. AASHTO specifies that results obtained fro m analyses of three- and four-lane bridge decks where all lanes are loaded simul taneously are to be multiplied by proposed reduction factors. This research will investigate the significance of the reduction factors propose d by AASHTO. Design trucks loads are first placed transversally in all lanes as a reference case. Design loads in two out of three, three out of four, and two out of four lanes are then investigated. The wheel load distribution on the bri dge slab at the critical section for the fully loaded and reduced conditions are calculated and compared. The results are assessed with AASHTO procedures, and a correlation between the reduced conditions and the AASHTO 10% and 25% reductio n factors is made. This research will assist bridge engineers in quantifying the adjustment factors used in analyzing and designing multilane concrete slab bridges.

Book Integrated Numerical and Field Approachs to Improve Bridge Designs

Download or read book Integrated Numerical and Field Approachs to Improve Bridge Designs written by Inmar Badwan and published by . This book was released on 2005 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Bridge design codes provide a set of technical requirements for safe and acceptable design. However, several design requirements need evaluation and field verification to asses their accuracy. Those associated with the full-depth shear key joints in multi-beam decks, load distribution in highly skew continuous bridges, and permit load bridge rating are reviewed in the context. Multi-beam decks can be made by precast units that are post-tensioned together with shear keys and transverse post-tensioning. The performance of the longitudinal joints with regards to load transfer and water tightness is one of the design features of interest. To transfer load between the adjacent units, the joints are filled with grout material. The transverse post-tensioning stress is employed to prevent excessive opening of these joints. Live load tests on multi-beam bridge were performed to obtain actual load distribution data. The study presents the test results and an associated finite element analyses. A simplified method based upon grillage analogy is developed to quantify required transverse post-tensioning stresses in the longitudinal joints. The efficiency of the joints was evaluated by comparing with a hypothetical monolithic slab structure and by the distribution of loads in the transverse direction. The post-tensioning stresses as calculated according to the method were compared with the requirements of the AASHTO LRFD provisions. Estimation of the span and support moment is required to develop a realistic design for skew continuous bridges. Distribution factors recommended by the code provide convenience and simplistic methods to calculate the moments on bridge girders. Refined formulas for estimating the load distribution factors are provided in the current AASHTO LRFD Bridge Design Specifications. A considerable amount of literature is available on field verification studies of right angle steel girder bridges; however studies on highly skew bridges are relatively limited. Previous studies on highly skew bridges have verified the distribution characteristics either analytically or experimentally using prototype bridges. The current study presents a live load field test carried out on a 60-degree skew three-span continuous steel girder bridge. The results are used to derive quantitative information regarding the actual transverse load distribution characteristics of the bridge to asses the accuracy of the current methods. To account for the application of overloads, the LRFR permit load rating was modified by introducing the fatigue damage of overloads. The study used a modification factor referred to as the fatigue index to point to the damage causing effect of overloads. A method is developed to calculate the modification factor. The method considers the fatigue damage that may be caused by overloads as well as the stresses induced by normal traffic. The approach assumes that fatigue index for a specific overload is proportional to the total number of stress cycles required to increase the crack size to the crack threshold at stress induced by normal traffic. The number represents the overload stress cycles that would produce a crack size at which normal traffic stress cycle is able to contribute to the crack growth. The fatigue index as determined by the method reflects the severity of an overload and its potential for causing fatigue damage."--P. iii-iv.

Book Prediction of Structural Response of Distressed Bridge Using Finite Element Method

Download or read book Prediction of Structural Response of Distressed Bridge Using Finite Element Method written by Shreeram Krishna and published by . This book was released on 2004 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bridges must be evaluated to make sure they are capable of carrying the present load and most importantly the future load within the serviceability limit. The analysis of the loads consists of measuring the load distribution and the effect on the structural components. This can be done experimentally using the available field test instruments or also known Proof Load Test. The main objective of the field test is to measure the deflections, stresses and strains at the critical bridge components subjected to a predetermined load.. However, field test can be expensive in terms of cost and time. The development of a realistic analytical model seems to be an alternative to provide a supplementary load capacity assessment with lesser cost and time. This paper will provide a comprehensive review on the Finite Element Model prediction on the structural response of a distressed bridge with comparison made to the actual response obtained from the field load test results. Comparison reveals that the predicted model behaves similarly to the actual bridge response under live loading but it was also noted some variation or difference in term of the magnitude of responses. These differences are mainly attributed to the existence of field factors which were not included in the model.

Book Live load Testing and Finite element Modeling of a Fracture Critical Bridge

Download or read book Live load Testing and Finite element Modeling of a Fracture Critical Bridge written by Jake L. Morrill and published by . This book was released on 2016 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Utah Transportation Center, in conjunction with CAIT at Rutgers, sponsored a study that investigated the distribution factors and load ratings of a continuous, steel I-girder bridge. The SH-52 Bridge over the Snake River is located on the Idaho-Oregon border near Payette, Idaho. The bridge was built in the 1950's and presently supports two lanes of traffic. A finite-element model of the bridge was calibrated with the results from a live-load test. For the live-load test, the bridge was instrumented at nine longitudinal cross section locations with 62 strain gauges attached on the girders, stringers, and intermediate diaphragms. The live-load was applied with two heavy trucks that were driven along three predetermined load paths. The calibrated finite-element model was used to quantify moment distribution factors and load ratings for the bridge. The finite-element distribution factors were compared to those calculated according to the AASHTO Standard and AASHTO LRFD Specifications. The distribution factors from both AASHTO codes were found to be unconservative for the girders and overly conservative for the stringers. The model was also used to quantify the effect of the transverse diaphragm members on the live-load distribution. Distribution factors were calculated with and without the diaphragm members. The diaphragms were found to increase the distribution of moments by over 20% for both positive and negative moments.

Book Load Capacity of Older Continuous Concrete Slab Bridges

Download or read book Load Capacity of Older Continuous Concrete Slab Bridges written by Srinivasa L. Iyer and published by . This book was released on 1987 with total page 278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Dynamic Analysis of Bridges Using the Finite Strip Method

Download or read book Dynamic Analysis of Bridges Using the Finite Strip Method written by Abdulkarim Hassan Ali and published by . This book was released on 2000 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic analysis of highway bridges is very complex because of the interaction between the moving vehicle load and the bridge response. Analytical methods such as beam theory and orthotropic plate theory are applicable only to simple structures and highly simplified moving vehicle load models. The beam theory is applicable only to long and narrow bridges since it neglects the effect of transverse flexibility of the bridge. The orthotropic plate theory is only applicable to slab bridges under simple vehicle load models as complex vehicle models render the differential equation of equilibrium difficult or impossible to solve. The finite element method is a very powerful and versatile technique which can be applied to deal with any specific configuration of bridge structure, supports and vehicle load models. However, the efficiency of the method needs to be improved because the finite element solutions usually require too much computer time, too large core storage and too much data input. In addition to these deficiencies, in order to simulate the local of the moving concentrated wheel loads the finite element mesh should be refined in both directions. The finite strip method has already proven to be the most efficient numerical technique for the static analysis of bridges. In fact the method is even more efficient for dynamic analysis of bridges. The structure can be divided into a number of finite strips. In each strip the displacement components at any point are expressed in terms of the displacement parameters of nodal lines by means of simple polynomials in the transverse direction and a continuously differentiable smooth series in the longitudinal direction. Thus, the number of dimensions of the analysis is reduced by one. The minimum number of degrees of freedom along a nodal line in the finite strip method is equal to twice times the number of terms used in the series and this is normally much less than that for finite element method, which requires a minimum of three times the number of nodes along the same line. Hence the size and the bandwidth of the matrices are greatly reduced, and consequently it can be handled by personal computers and solved in much shorter time. In this study the finite strip method is applied to dynamic analysis of simply supported single span slab bridges, slab-on girder bridges, box girder bridges and multi-span bridges by using various vehicle load models. Harmonic analysis of beams is covered in Chapter Two as an introduction for the finite strip method. A FORTRAN computer program capable of analyzing all the topics covered in this thesis is also developed.