30 research outputs found
Numerical analysis of the embedded abutments of integral bridges
A numerical case study is presented, which investigates the performance of embedded integral bridge abutments and the maximum magnitude and distribution of earth pressure within the retained soil. The Three Surface Kinematic Hardening model is adopted in the numerical analysis, which successfully reproduced key features of soil behaviour under small strain cyclic loading. The results show that the earth pressures behind the abutment change in a complicated way, while the largest bending moments in the abutment wall increase with cycles at a decreasing rate, with a final value far less than the one derived from current design standards. A number of factors have been investigated and the influences of the wall flexure and soil stiffness are highlighted. The research results will lead to safe and economic design of such structures
Model for Particle Masses, Flavor Mixing, and CP Violation Based on Spontaneously Broken Discrete Chiral Symmetry as the Origin of Families
We construct extensions of the standard model based on the hypothesis that
the Higgs bosons also exhibit a family structure, and that the flavor weak
eigenstates in the three families are distinguished by a discrete chiral
symmetry that is spontaneously broken by the Higgs sector. We study in detail
at the tree level models with three Higgs doublets, and with six Higgs doublets
comprising two weakly coupled sets of three. In a leading approximation of
cyclic permutation symmetry the three Higgs model gives a ``democratic''
mass matrix of rank one, while the six Higgs model gives either a rank one mass
matrix, or in the case when it spontaneously violates CP, a rank two mass
matrix corresponding to nonzero second family masses. In both models, the CKM
matrix is exactly unity in leading approximation. Allowing small explicit
violations of cyclic permutation symmetry generates small first family masses
in the six Higgs model, and first and second family masses in the three Higgs
model, and gives a non-trivial CKM matrix in which the mixings of the first and
second family quarks are naturally larger than mixings involving the third
family. Complete numerical fits are given for both models, flavor changing
neutral current constraints are discussed in detail, and the issues of
unification of couplings and neutrino masses are addressed. On a technical
level, our analysis uses the theory of circulant and retrocirculant matrices,
the relevant parts of which are reviewed.Comment: Revtex, 59 pages including four tables at en
Behaviour under static loading of metallic beams reinforced with a bonded CFRP plate
CFRP plates have been employed widely in the repair and upgrading of bridges and building in recent years. When they are used in the upgrading of metallic beams, the weakest link is the adhesive bonding, and plate peel is the most important failure mode due to the high stress concentration at the end of the plates. This paper presents the results of a study on the influencing factors on the strengthen of the metallic beams reinforced by different types of CFRP plates, the effects of the tapers at the plate ends and of the spew fillets beyond the plate ends. The test results also validate the theoretical results of stress analysis. The use of longer and tapered plates is suggested as a solution for improvement
Effect of plate end and adhesive spew geometries on stresses in retrofitted beams bonded with a CFRP plate
Adhesive bonding technique has been widely used in construction as an alternative to conventional joint techniques, particularly in retrofitting schemes using carbon fibre reinforced polymer (CFRP) plates. Spew fillets and end tapers have been suggested for reducing the stress concentration in the adhesive layer of retrofitted beams. In this paper, finite element (FE) analyses were employed to determine the effects of the spew fillet and the taper on interfacial adhesive stresses and the strains in the CFRP plate. A total of eight cases with different configurations of spew fillet and different tapers have been considered. The results largely agree with the findings on lap joints, but the effect of spew fillets is far less than that for lap joints. Moreover, the results show a combination of an inside taper in the plate and a triangular fillet give the most reduction in the maximum interfacial stresses. The results of the FE analyses also show that the effect of spew fillet size on the strain close to the plate end, which confirms previous analytical and experimental results
Adhesive bonding in steel beams strengthened with CFRP
The strengthening of metallic beams with a bonded carbon-fibre-reinforced polymer (CFRP) plate has found many applications in bridge and building structures in recent years. The structural behaviour of the adhesive bonding in this technique is the most distinct element to be considered. In this paper, previous analytical, experimental and numerical studies under static and fatigue loadings by the present authors are reviewed. An S –N curve based on the peak interfacial stresses is proposed to predict the fatigue life to crack initiation of the retrofitted beams. An equation to predict the fatigue life during the crack propagation has also been developed. Finally, the geometric effects of the spew fillet and of the taper at the plate end of the retrofitted beam are discussed. In the conclusion, design recommendations for steel beams strengthened by bonded CFRP plates are detailed based on the findings obtained from the studies presented.<br/