Analysis of Pure Bending Vertical Deflection of Improved Composite Box Girders with Corrugated Steel Webs

Steel bottom plates are applied as replacements for the concrete bottom plates in order to reduce the dead weight of the composite box girders with corrugated steel webs and steel bottom plates (CSWSB). Due to the change in the material, the previous analytical calculation methods of vertical deflection of composite box girders with corrugated steel webs (CSWs) cannot be directly applied to the improved composite box girders. The shear lag warpage displacement function was derived based on the shear deformation laws of the upper flange and the bottom plates of the improved composite box girders. The equations for the calculation of the shear deformation and the additional deflection due to the shear lag of continuous and simply supported composite box girders with CSWSB under concentrated and uniformly distribution loads were derived by considering the double effects of the shear lag and the shear deformations of the top and the bottom plates with different elastic moduli. The analytical solutions of the vertical deflection of the improved composite box girders include the theory of the bending deflection of elementary beams, shear deformation of CSWs, and the additional deflection caused by the shear lag. Based on the theoretical derivation, an analytical solution method was established and the obtained vertical deflection analytical solutions were compared with the finite element method (FEM) calculation results and the experimental values. The analytical equations of vertical deflection under the two supporting conditions and the two load cases have verified the analyses and the comparisons. Further, the additional deflections due to the shear lag and the shear deformation are found to be less than 2% and 34% of the total deflection values, respectively. Moreover, under uniform distributed load conditions, the deflection value was found to be higher than that of the under concentrated load condition. It was also found that the ratio of the deflection caused by the shear lag or the shear deformation to the total deflection decreased gradually with the increase in the span width ratio. When the value of the span width ratio of a single box and single chamber composite box girder with CSWSB was equal to or greater than 8, the deflections caused by the shear lag and the shear deformation could be ignored.

Shear Lag Effect and Accordion Effect on Dynamic Characteristics of Composite Box Girder Bridge with Corrugated Steel Webs

This study proposed a dynamic characteristic analytical method (ANM) of a composite box girder bridge with corrugated steel web (CBGCSW) by completely considering the impact of shear lag effect and accordion effect of corrugated steel webs. Based on energy principles and variational principles, a vibration differential equation and the natural boundary conditions of a CBGCSW were developed. The analytical calculation formula for solving the vibration differential equation was then obtained. The results calculated using the ANM agreed well with previous experimental results, which validated the correctness of ANM. To demonstrate the superiority of the ANM, the vibration frequencies of several abstract CBGCSWs with varying ratios of span–width, obtained using the elementary beam theory (EBT) and the finite element method (FEM), were compared with those obtained by ANM. The efficacy of the ANM was verified and some meaningful conclusions were drawn which are helpful to relevant engineering design, such as the observation that a higher natural vibration frequency and smaller span–width ratio significantly magnified the shear lag effect of CBGCSW. The first five-order natural vibration frequencies of the CBGCSW were significantly lower than those of the composite box girder bridge with general steel web (CBGGSW), which indicates that the impact of the accordion effect is significant.

Hydrodynamical Aspects of Pontoon Optimization for a Side-Anchored Floating Bridge

Long floating bridges supported by pontoons with span-widths between 100 m and 200 m are discrete hydro-elastic structures with many critical eigenmodes. The response of the bridge girder is dominated by vertical eigenmodes and coupled horizontal modes (lateral) and rotational modes (about the longitudinal axis of the bridge girder). This paper explores the design principles used to reduce the response with regards to these eigenmodes. It is shown for a floating bridge with 200 m span-width that by inserting a bottom flange the vertical eigenmodes can be lifted out of wind-driven wave regime. It is also shown that selecting a pontoon length that leads to cancelation of horizontal excitation forces is beneficial, and that the geometrical shaping of the pontoon can be efficient to decrease the bridge response.

Hydrodynamical Aspects of Pontoon Optimization for a Side-Anchored Floating Bridge

Long floating bridges supported by pontoons with span-widths between 100m and 200m are discrete hydro-elastic structures with many critical eigenmodes. The response of the bridge girder is dominated by vertical eigenmodes and coupled horizontal modes (lateral) and rotational modes (about the longitudinal axis of the bridge girder). In this paper it is focused on design principles to reduce the response with regards to these eigenmodes. It is shown for a floating bridge with 200m span-width that by inserting a bottom flange the vertical eigenmodes can be lifted out of wind driven wave regime. It is also shown that selecting a pontoon length that give cancellation of excitation forces is beneficial, and that the geometrical shaping of the pontoon can be efficient to decrease the bridge response.

Phase Behavior Studies on ZnS Nanoparticles Doped Liquid Crystal Mixture

The Liquid Crystalline (LC) mixture is prepared from chiral compound of cholesteryl nonanoate and non-chiral compound of biphenylpyrimidine. The phase change with temperature and corresponding textures of the LC mixtures are analyzed by Polarizing Optical Microscope (POM). LC mixture at its isotropic state is doped with 1% of ZnS nanoparticles and its influence on mesophases is discussed. Normally blue phase is identified within narrow thermal width. The note worthy observation is that the blue phase and cholesteric phase with extended thermal span width in the ZnS doped LC mixture. Also the thermal stability factor of the different liquid crystal phases is discussed.

Experimental Investigations for Compression-Flexure Characters of Laminated Box Beam Columns

In the action of bending load and axial compression, the deflection of the beam presents character of compression-flexure. For the thin-walled carbon fiber laminated box beam column, the beam deflections not only relate with load but also with the ply angle of layer, span width ratio. By using the experimental method, this paper this paper focuses on the experimental investigations of the compression-flexure characters of the laminated box beam column, in which the features of beam deflection variation with the span width ratio, ply angle, the axial compression ratio are given.

Numerical Analysis for Geometry Nonlinear Characters of Laminated Box Beam Columns

In the action of bending load and axial compression, the deflection of the beam presents character of geometry nonlinear. For the thin-walled carbon fiber laminated box beam column, the beam deflections not only relate with load but also with the ply angle of layer, span width ratio. By using the method of numerical, this paper analyzed and summarized the beam deflection variation with the span width ratio, ply angle, the axial compression ratio for the simply supported laminated box beam column under the axial compression and bending load.

Study of Free Vibration Characteristic of Continuous Box-Girder Based on Hamilton Principle

Based on Hamilton principle, the differential equation of free vibration and the corresponding boundary conditions of continuous box girder with consideration for the shear lag effect meeting self-equilibrated stress, shear deformation as well as rotational inertia were induced. The ANSYS finite element solutions were compared with the analytical solutions by calculation examples and the validity of the proposed approach was verified. The obtained formulas developed the shear lag theory. Some meaningful conclusions for engineering design were obtained. The contribution of the shear lag effect decreases each order natural frequency of the continuous box-girder, at the same time the higher the order natural frequency is, the greater the influence of shear lag effect on natural frequency of continuous box-girder is. The shear-lag effect of continuous box girder increases when frequency order rises, and increases while span-width ratio decreases.

Influence of Shear Lag and Shear Deformation Effects on Deflection of Composite Box Girder with Corrugated Steel Webs

The shear lag and shear deformation effects on deflection of composite girder with corrugated steel webs (CGCSW) was studied. The influence of shear lag and shear deformation effect was expressed by deflection coefficient δ1 and δ2. Parametric analysis within a scope of dimensions of built-in girders was performed, including girder span, width, height, thickness of concrete flange and thickness of steel web. The results show that the deflection coefficient of shear lag effect is approximately directly proportional to square of width-span ratio, while the deflection coefficient of shear deformation effect is related to all parameters. It’s suggested that shear lag effect on CGCSW’s deflection be neglected when width-span ratio is smaller than 1/9, and shear deformation effect should always be considered.

Impact Tests for IRIS_2010 Benchmark Exercise

IRIS_2010 benchmark was an exercise in OECD/NEA/CSNI framework. This exercise concentrated on improving robustness assessment methodologies for structures impacted by missiles. This article describes experimental tests included in the exercise. These tests consisted of two tests for bending, three for punching and one for combined punching and bending behaviour of reinforced concrete walls under impact loading. The test for combined behaviour was carried out in Meppen, Germany in the 1980’s, while all the other tests were carried out by VTT Technical research centre of Finland during the spring of 2010. In the bending behaviour tests, 0.15 m thick simply supported square concrete walls with span width of 2 m were impacted with soft missiles weighing ∼50 kg and having velocity of ∼110 m/s at the impact moment. The impacts resulted maximum displacements of 29-32 mm at the centre of the wall with the permanent values being 8-9 mm. In the punching behaviour tests, similar walls but with thickness of 0.25 m were impacted with hard missiles weighing ∼47.5 kg and having velocity of ∼135 m/s at the impact moment. The impacts resulted perforation of the wall by the missile with residual velocity of the missile being 34-46 m/s. In addition, the walls suffered severe scabbing on the backside with the scabbed area being 1.00-1.12 m2.