Effects of Wingwall Configurations on the Behavior of Integral Abutment Bridges

This research includes parametric studies performed with the use of three-dimensional nonlinear finite element models in order to investigate the effects of cantilever wingwall configurations on the behavior of integral abutment bridges located on straight alignment and zero skew. The parametric studies include all three types of cantilever wingwalls; inline, flared, and U-shaped wingwalls. Bridges analyzed vary in length from 100 to 1200 feet. Soil-structure and soil-pile interaction are included in the analysis. Loadings include dead load in combination with temperature loads in both rising and falling temperatures. Plasticity in the integral abutment piles is investigated by means of nonlinear plasticity models. Cracking in the abutments and stresses in the reinforcing steel are investigated by means of nonlinear concrete models. The effects of wingwall configurations are assessed in terms of stresses in the integral abutment piles, cracking in the abutment walls, stresses in the reinforcing steel of abutment walls, and axial forces induced in the steel girders. The models developed are analyzed for three types of soil behind the abutments and wingwalls; dense sand, medium dense sand, and loose sand. In addition, the models consider both the case of presence and absence of predrilled holes at the top nine feet of piles. The soil around the piles below the predrilled holes consists of very stiff clay. The results indicate that for the stresses in the piles, the critical load is temperature contraction and the most critical parameter is the use of predrilled holes. However, for both the stresses in the reinforcing steel and the axial forces induced in the girders, the critical load is temperature expansion and the critical parameter is the bridge length. In addition, the results indicate that the use of cantilever wingwalls in integral abutment bridges results in an increase in the magnitude of axial forces in the steel girders during temperature expansion and generation of pile plasticity at shorter bridge lengths compared to bridges built without cantilever wingwalls.

An Investigation Into The Perceptions Of Parents And Teachers Regarding The Adjustment To Sixth Grade Across School Configurations

A qualitative study was conducted in a large urban school district in the Mid-Atlantic region of the Unites States to investigate the perceptions of parents and teachers regarding the adjustment to sixth grade across school configurations. The investigation revealed the psychosocial and environmental factors that have an impact on sixth graders according to their grade span configurations. The study was conducted in the large urban school district, referred to as the “County,” which has a history of low and inconsistent achievement of sixth graders across a variety of grade span configurations. Through the analysis of the teacher and parent interviews conducted in two K-6 schools and two 6-8 middle schools, four themes were identified: transitioning, cultural awareness, social adjustment, and preparedness. The four themes emerged from the perceptions and observations of sixth graders, as shared by parents and teachers of sixth graders, according to their grade span configurations. Each of the responses was compared according to the identified grade span configuration K-6 and 6-8. From the data collected, recommendations were provided to the school district in which the study was conducted to better support teachers, parents, and sixth graders. Further research was also recommended of larger samples of sixth grade span configurations to better understand the complex dynamics of the relationships between grade span configurations for sixth graders and student achievement.