Live‐Load Moments for Continuous Skew Bridges

Khaleel, Mohammad A.; Itani, Rafik Y.

doi:10.1061/(asce)0733-9445(1990)116:9(2361)

Cited by 33 publications

(10 citation statements)

References 5 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, it is a known fact that skew supports change the load path and loads transfer to the supports through their shortest path. A few researchers showed that the maximum bending moment in a girder in a skew bridge is smaller than its straight counterpart (Khaleel & Itani, 1990), and the shear in the girder at the obtuse corner is more significant when compared to those obtained in a non-skew (straight or right-angle) bridge of the same length and width (Menassa et al, 2007). Hence, an additional factor needs to be considered to adjust the load distribution factors of straight bridges when the engineer designs or evaluates a skew bridge.…”

Section: Introductionmentioning

confidence: 99%

Load Distribution Factors in Straight and Skew Concrete I-Girder Bridges

Iranmanesh

2024

Preprint

View full text Add to dashboard Cite

<p>Skew bridges in modern highways have become increasingly popular for economic and aesthetic considerations. The current Canadian Highway Bridge Design Code (CHBDC) specifies skew factor equation for shear at the obtuse corner for braced steel I-girder bridges. However, skew factors for concrete I-girder bridges for girder moment and shear at obtuse and acute corners as well as middle supports due to CHBDC truck loading are yet unavailable. Also, CHBDC load distribution factor equations for moment and shear in straight bridges do not include the presence of concrete traffic barriers and intermediate diaphragms as integral parts of highway bridges. Moreover, literature review revealed that CHBDC overestimates the moment and shear at fatigue limit state design of slab-on-girder bridges. Despite the availability of computer software for bridge analysis, designers prefer simplified analysis methods to reduce the time and cost spent in the design. A practical-design-oriented parametric study was conducted, using the finite element modelling to address the shortcomings and gaps found in CHBDC. The first study included the analysis of straight and skew concrete I-girder bridges under dead load, while the second study included the analysis of such bridges under CHBDC truck loading conditions. The third study included the effect of concrete barrier stiffness and concrete intermediate diaphragms on the moment and shear distribution factors for this type of bridge. Different bridge configurations were considered to cover key parameters such as span length, skew angle, number of girders and girder spacing. The obtained results were compared with those available in CHDBC, AASHTO LRFD Bridge Design Specifications and previous research related to slab-on-girder bridges. Using the data generated from the parametric study, sets of empirical equations for moment and shear distribution factors for the studied bridge configurations under dead and live load were deduced to design such bridge types more reliably and economically. Results show that inclusion of intermediate diaphragms and concrete barriers built integrally with the deck slab generally affect bridge performance. This conclusion can be used to evaluate existing bridges since any additional girder strength would decide on keeping the bridge in service or address its structural deficiency.</p>

show abstract

Section: Introductionmentioning

confidence: 99%

Load Distribution Factors in Straight and Skew Concrete I-Girder Bridges

Iranmanesh

2024

Preprint

View full text Add to dashboard Cite

show abstract

“…where R is the multiple presence factor; W is the width of lanes; and N g is the number of girders. Some investigations modified the GDF calculation methods of curved [3,14,15] and skewed [16,17] bridges based on AASHTO Standard specification and AASHTO LRFD specification. However, it was found that these methods overestimated the GDF and underestimated the stiffness of the bridge [18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Analytical Solutions for Girder Distribution Factor in Steel‐Concrete Composite Girders with the Effect of Parapets

Zhang

Liu

Feng

et al. 2021

Advances in Civil Engineering

View full text Add to dashboard Cite

The existing studies have shown that parapets have great influence on the girder distribution factor (GDF) of bridges. However, there is no method in the design guide to estimate the GDF considering the effect of parapets. This research aims to develop a simplified method for estimating the GDF by considering the effect of parapets. First, a simply supported steel-concrete composite girder bridge was tested to investigate the effect of parapets on the GDF. Then, finite-element (FE) model was established and verified by the field test data of strain and deflection. In addition, error study showed that the bending stiffness of the bridge was increased by about 92% and 19.1%, respectively, due to the effects of parapet and continuous layer. As the effect of the continuous layer on each girder was relatively uniform, the simplified method was optimized only considering the effect of the parapet. Finally, the effect of the parapet on the GDF was compared and discussed. Considering the effect of the parapet, the GDF of the exterior girder calculated by the simplified method and FE analysis decreased by about 26.92% and 23.53%, respectively, and the adjacent interior girder decreased by about 15.22% and 12.77%, respectively. Comparing the GDF calculated by the AASHTO LRFD specifications, the GDF calculated by the simplified method decreased by about 30.77% in the exterior girder and 41.30% in the interior girder, respectively. The results indicate that the method of calculating the GDF without considering the effect of the parapet in AASHTO LRFD specifications is conservative. The GDF calculated by the simplified method was basically close to the field test results, meaning that the proposed simplified method considering the effect of the parapet was relatively accurate.

show abstract

“…Although Henry's method [18] is solely a function of the number of girders and the width of bridge roadway, it is widely used because it calculates highly conservative values for skewed bridges' LDFs [19]. The simplified models developed by Tarhini and Frederick [15] and Khaleel and Itani [20] yield accurate results only for single or two-lane loaded non-skewed bridges, while Menkulasi et al [21] proposed a set of equations to quantify LDFs for short-to medium-span composite precast inverted T-beam bridges that produce reasonably accurate results over the specified range of applicability.…”

Section: Introductionmentioning

confidence: 99%

Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads

2018

View full text Add to dashboard Cite

Because the methods used to compute the live load distribution for moment and shear force in modern highway bridges subjected to vehicle loading are generally constrained by their range of applicability, refined analysis methods are necessary when this range is exceeded or new materials are used. This study developed a simplified method to calculate the live load distribution factors for skewed composite slab-on-girder bridges with high-performance-steel (HPS) girders whose parameters exceed the range of applicability defined by the American Association of State Highway and Transportation Officials (AASHTO)'s Load and Resistance Factor Design (LRFD) specifications. Bridge databases containing information on actual bridges and prototype bridges constructed from three different types of steel and structural parameters that exceeded the range of applicability were developed and the bridge modeling verified using results reported for field tests of actual bridges. The resulting simplified equations for the live load distribution factors of shear force and bending moment were based on a rigorous statistical analysis of the data. The proposed equations provided comparable results to those obtained using finite element analysis, giving bridge engineers greater flexibility when designing bridges with structural parameters that are outside the range of applicability defined by AASHTO in terms of span length, skewness, and bridge width.

show abstract

Live‐Load Moments for Continuous Skew Bridges

Cited by 33 publications

References 5 publications

Load Distribution Factors in Straight and Skew Concrete I-Girder Bridges

Load Distribution Factors in Straight and Skew Concrete I-Girder Bridges

Analytical Solutions for Girder Distribution Factor in Steel‐Concrete Composite Girders with the Effect of Parapets

Live Load Distribution Factors for Skew Stringer Bridges with High-Performance-Steel Girders under Truck Loads

Contact Info

Product

Resources

About