Multimodal Response Spectrum Method Analysis of Integral Abutment Curved Box Girder Bridge
In order to simplify analysis of the dynamic characteristics and seismic response of the integral abutment curved box bridge(IACBB), automatic iteration of the multimode modal response spectrum(MMRS) is realized by APDL language of the structure analysis software ANSYS according to the IACBB's structural characteristics. The realization flow of iterative MMRS in Ansys were presented. and the availability and precision of the iterative MMRS were examined by the time-history analysis. The result shows that 1）the iterative MMRS is a efficient simplify method, and can be used as an estimating method of seismic analysis for the bridge. And the method provides a reference for future similar structures. 2）several conclusions of earthquake response are given. The research results are helpful for the knowledge of mechanics property of the type of the bridges.
Nonlinear Analysis of Integral Bridges: Finite-Element Model
Integral abutment bridges (IABs) are jointless bridges where the deck is continuous and connected monolithically with the abutment walls. The biggest uncertainty in the design of these bridges is the reaction of the soil behind the abutments and next to the foundation piles, especially during thermal expansion. This lateral soil reaction is inherently nonlinear and is a function of the magnitude and nature of the wall displacement. Handling the soil-structure interaction in the design of IABs has always been problematic, usually requiring iterative, equivalent linear analysis. This paper describes the implementation of a full 3D finite-element model of an IAB system which explicitly incorporates the nonlinear soil response. This paper also presents the results from a small parametric study on a sample bridge where the soil compaction levels in the cohesionless soils behind the wall and adjacent to the piles were varied. These results show that the level of compaction in the granular backfill strongly dominates the overall soil reaction, and that this reaction greatly impacts the overall structural response of the bridge system.
A new power measuring circuit using a bridge-connected magnetic circuit and another magnetic core
The authors describe the operating characteristics of an oscillating circuit using a bridge-connected magnetic circuit and another magnetic core. A square-shape output voltage is obtained in the oscillating circuit. The pulsewidth in positive and negative half cycles of output voltage changes with the current of the U-form core windings and with the signal voltage applied to the exciting windings. The mean value of the output voltage varies in proportion to the product of the current and the signal voltage. Utilizing this feature, an application of the oscillating circuit to a novel power measuring circuit of simple construction is presented. >