Published online on September 2016.
Scott Brendler, Yasser Khodair
Abstract:This research examines the accuracy of both AASHTO Standard Specification and AASHTO LRFD girder distribution factors (GDF) for use with designing integral abutment bridges. To evaluate the GDFs, the integral abutment Scotch Road Bridge was modelled in the finite element software Abaqus/Cae. The model was verified using temperature-displacement data recorded from April, 2003 to May, 2006. Following the validation of the finite element model, three loading cases including one, two, and three lanes, were run in Abaqus. The stress data obtained from each case was used to calculate the GDF for each girder at the locations of maximum positive and negative moments. Lane one loading provided the most reasonable results for AASHTO LRFD, while the AASHTO standard equation was overly conservative in all cases. The positive and negative results yielded similar GDF ratios to each other for one lane loaded. The positive and negative Abaqus/Cae one lane loaded GDF values were 20% and 25% lower than AASHTO 2012 respectively, while being 50% lower than AASHTO 1996. Both AASHTO GDF equations were overly conservative for both two and three lanes loaded. The Abaqus calculated GDF was approximately 50% and 60% lower for two and three lanes loaded compared to AASHTO LRFD. A parametric study was conducted to investigate the effect of bridge skew, pile length, and pile spacing. We found that AASHTO 2012 better predicts the effect of skew in the calculated GDF, however, neither reducing the number of piles nor adjusting the pile length in a bridge creates a significant change in the GDF ratios when pile fixity is maintained.
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 1-12
Parimal Bhattacharya, Abhishek Roy, Achal Garg
Abstract:Conventional method of bridge construction if adopted would mean long gestation period and ultimately costly. Therefore, it was desired that some alternative scheme must be developed and adopted to overcome the situation. This scheme must be economical, less time consuming, easy to implement and feasible with local infrastructure. In this report such a scheme is outlined for installation of the two enabling girders (total 2 in numbers) on the river Ganges, which will meet these objectives. The feasibility of the scheme has been established with detail engineering calculation based on the practical constraints prevalent at the site.
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 13-27
Abstract:Several efforts have been made in the last decades to address the importance of changing the focus of current seismic design codes from merely preventing collapse in major earthquakes and controlling the damage in minor earthquakes to a more general design philosophy which takes into account multiple performance objectives based on quantifiable performance criteria; this design philosophy is referred to as Performance Based Design (PBD). A Displacement-based seismic design procedure is proposed and elaborated for concrete bridges with continuous deck integral with the piers. It includes a simple estimation of inelastic deformation demands (chord or plastic hinge rotations in piers, curvatures for the deck) via elastic 5%-damped modal response spectrum analysis . The applicability of the equal displacement rule at the level of member deformations is checked through nonlinear static analyses of one representative regular four Spans Bridge, steel box girders and piers of various cross-sections and about equal and very different heights. A four-span bridge of 100 meters in total length was analyzed using both the Nonlinear Static Procedure and Displacement based design Method. The main aim and product of the research line has been the formation of a model code for displacement-based seismic design.
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 29-44
Adel Elfayoumy, Nasim Uddin
Abstract:Heavy truck traffic affects the service life of highway bridge superstructures. Damage typically occurs in the bridge deck and in the superstructure main elements. This damage may be mainly due to a bending moment that could exceed the load capacity of the bridge, and/or fatigue damage of the super structure girders (steel bridges). The goal of this research is to characterize bridge population sensitive to bending moment. This was done based on a static analysis of steel and prestressed concrete (PSC) girder bridges of different configurations subjected to the AASHTO design truck (HL-93), the 97-kips trucks (97-S and 97-TRB), and AASHTO legal rating truck (3S2). Moreover, based on the site-specific WIM data, the site-specific representative heavy vehicles (160 and 170 kip) and the site specific fatigue truck (85 kip) were analyzed. For static analysis, five different steel and PSC girder bridges of different practical spans (30, 60, 90, 120, and 140 ft) and configurations were modeled by two different programs to provide confidence on the accuracy of the analysis, a commercial program (CSiBridge) and an AASHTOWare Bridge Rating program. The results provide the bending moment at the most critical sections of girders under the selective heavy truck presence case. For the PSC bridges, the site-specific representative heavy vehicle induced the most critical load case for the 60- to 100-ft long PSC bridges; however, the 30-ft-long steel bridge was unsafe under the application of the strength-I load factors but turned to be safe with the application of the strength-II load factors.
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 45-62
Amir Fatollahzadeh, Morteza Naghipour, Gholamreza Abdollahzadeh
Nowadays, Engineers have built some tremendous structures all around the world, as a result, engineers have confronted with several unknown aspects of design and construction methods. Progressive collapse in structures has always been a serious threat, and historically has caused several vast demolitions of man-made structures and lead to damages and loss of lives. One of the causes of these damages is the failure in a number of elements during ultimate events such as earthquake or severe wind. In these types of failures, earthquake or wind act as primary perturbation factors which propagate the local failure within the structure. Although the structure is designed to resist against the specific earthquake, research reveals that failure of only two elements is capable to cause consequent damages. For this purpose, three earthquake accelerations will be exerted on the structure and simulation of two critical cables failure will be performed simultaneously. The results show that the mentioned situation during Tabas and Loma Prieta earthquakes will lead to progressive collapse, whereas the structure can withstand two cables removal during the Bam earthquake. To avoid this destruction, six base isolations are installed below the structure. Analyses show that this approach can limit the amplitude of axial force below the ultimate strength and progressive collapse can be avoided. Abstract:
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 63-72
Rajarshi Das, A. D. Pandey, Soumya, M. J. Mahesh, S. Anvesh
Abstract:Since the structural system of bridges is different from buildings, only a few of many modern codes offer adequate methods of improving resistance against progressive collapse for bridges. Although great efforts have been contributed to the progressive collapse of building structures, comparably small attention has been paid to the bridge structures, specially the cable-stayed bridges. This study demonstrates numerical modelling and analysis of a representative cable stayed bridge through the four analytical procedures, i.e., linear static, nonlinear static, linear dynamic and nonlinear dynamic to understand the collapse pattern. Furthermore, the response of the structural model is discussed for multiple types of cable loss cases. The Dynamic Amplification Factor of 2 has been approved by the results. The results also indicated a relation between the possibilities of failure progression with the location of the failed cables with respect to the pylons. Different progressive collapse patterns were also identified for nonlinear static and dynamic procedures.
International Journal of Bridge Engineering, Vol. 4, No. 2, 2016: pp. 73-91