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Lateral Load Distribution for Hollow Slab Bridge: Field Test Investigation
Yu Zhao,Xiaozhe Cao,Yongjun Zhou,Gangqiang Wang,Ruixin Tian 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.3
Distribution factors (DFs) for one typical cross-section as specified in the AASHTO LRFD specification can be varied when the bridge parameters such as span length, loading lanes and skew are changed. The diversity between design and actual DFs may be varied as the bridge parameters changed. To study this diversity, this paper presents an evaluation of lateral load DFs for prefabricated hollow slab bridges. The response of the bridge was recorded during the field test. This field test was divided into two stages: a concentrated force loading test on the prefabricated girder that settled on the bridge supports before the girders were connected transversely and a vehicle loading test after the girders were connected transversely. The instruments used to record the response of the bridge were strain gauges and dial indicators. The measured data in the multi-stages of the field test could be used to calibrate the support condition of the bridge and transverse connection between adjacent girders in the finite element model (FEM) using beam and plate elements. From the FEM, DFs for this hollow slab bridge were determined and compared with the DFs in the AASHTO LRFD specification. A parametric study using the calibrated FEM was then used to investigate the effect of various parameters including span length, skew and bridge deck thickness on the DFs. It was found that AASHTO LRFD specification is conservative compared with the analysis in the FEM, while this conservatism decreased as the span length and skew of the hollow slab bridge increased.
Yan Yang1,Xiaochun Wei,Gongyao Shi,Fang Wei,Janeen Braynen,Jingshu Zhang,Baoming Tian,Gangqiang Cao,Xiaowei Zhang 한국식물학회 2017 Journal of Plant Biology Vol.60 No.2
Success of interspecific hybridization relies mostly on the adequate similarity between the implicated genomes to ensure synapsis, pairing and recombination between appropriate chromosomes during meiosis in allopolyploid species. Allotetraploid Brassica napus (AACC) is a model of natural hybridization between Brassica rapa (AA) and Brassica oleracea (CC), which are originally derived from a common ancestor, but genomic constitution of the same chromosomes probably varied among these species through time after establishment, giving rise to cytogenetic difference in the synthetic hybrids. Herein we investigated meiotic behaviors of A and C chromosomes of synthetic allotriploid Brassica hybrids (ACC) at molecular and cytological levels, which result from the interspecific cross between natural B. napus (AACC) and B.oleracea (CC), and the results showed that meiosis course was significantly aberrant in allotriploid Brassica hybrids, and chromosomes aligned chaotically at metaphase I, chromosome bridges and lags were frequently observed from later metaphase I to anaphase II during meiosis. Simultaneously, we also noticed that meiosis-related genes were abruptly down-regulated in allotriploid Brassica hybrids, which likely accounted for irregular scenario of meiosis observed in these synthetic hybrids. Therefore, these results indicated that inter-genomic exchanges of A and C chromosomes could occur frequently in synthetic Brassica hybrids, and provided an efficient approach for genetic changes of homeologous chromosomes during meiosis in polyploid B.napus breeding program.