Bonded beams

Cap masonry walls with bond beam or solid blocks. 

Dickie. C.. and Morman, K., DM response of adhesively bonded beams Effect of environmental exposure and interfacial zone properties, Pol. Eng. Sci., 30. 4, 249 255 (1990). Hartman. B., Chapt. 2 of Sound and Vibration Damping in Polymers. ACS Symp Series 424 (1990). 

HORIZONTAL BOND BEAM OVER WINDOW ( FLOOR LEVEL ( ) NO( )... 

Geometry Wall length (0/1) (0/1/2) Bond beams Openings (0/1) (0/1/2) High slope (0/1) Soft/weak story (0/1)... 

Yang Q D, Thouless M D, Ward S M (1999), Numerical Simulations of Adhesively-Bonded Beams Failing with Extensive Plastic Deformation, Journal of Mechanics and Physics of Solids, 47, 1337-1353. 

The solutions covered in this introductory chapter all fall into a class of mechanics solutions known as mechanics of materials solutions because they involve assumptions that are typical of those made in the undergraduate level mechanics of materials courses. These closed form solutions are easy to apply, and can provide fundamental insights into the stress fields present within many idealized bonded joints. The shear lag concept is of fundamental importance to any bonded configuration where load is transferred from one adherend to another, primarily through shear. stresses within the adhesive layer. The beam on elastic foundation solution provides the basis for explaining the nature of bonded beams or plates subjected to lateral loads or applied moments. The material on residual stres.ses and curvature are important in understanding the significant stresses that can result from mismatches in properties such as the coefficients of thermal expansion. 

Yang, Q.D., Thouless, M.D. and Ward, S.M., Numerical simulations of adhesively-bonded beams failing with extensive plastic deformation. J. Mech. Phys. Solids, 47, 1337-1353 (1999). 

Dynamic mechanical thermal analysis (DMTA) has also been used by Brinson, et al.,t l to determine the suitability of the technique for evaluating damage in the adhesive bond from the viscoelastic properties of bonded beams and for evaluating the effects of various environmental conditions and various surface treatments. The authors considered that if the bond becomes damaged (either adhesive and/or interphase) due to excessive load, fatigue, moisture, or corrosion, it would seem likely that dissipation mechanisms or loss modulus and tan 5 would change. Therefore, they used DMTA to measure the viscoelastic properties of beams with simulated flaws and beams taken from lap specimens, which had been exposed to humidity and/or corrosion for extended periods. 

From the results of the work, it was concluded that it does appear that DMTA studies on bonded beams may allow the determination of progressive damage due to fatigue, moisture, corrosion, or, peihaps, to other environmental parameters. But it may be necessary to build special DMTA equipment more sensitive to small changes in damping behavior. 

Table 2 Comparison of weight, stiffness and strength for bonded beams.

Bonded beam thickness Honeycomb thickness Relative ... 

The laying of the masonry units varies according to the local techniques, the material, and the production form of the unit Industrial units are laid in courses (use of header courses or random laying constmction and keystones at the intersections) and the provision of collar joints filled with mortar (and possibly steel) and/or the inclusion of bond beam elements. The vertical elements are traditicaially built on a stone or brick or concrete footings, on which they rest or are tied to with reinforcement. Often, interior walls are in fact lighter constmction partitions of brick or wood not tied to the load-bearing system, or the wan intersections were poorly connected. 

O Figure 30.15 shows some results from Brearley et al. (2005) for a bonded beam structure which was vibrated in free-free flexure. The beam was made of two equal U-shaped sections joined by rivets, bolts, an adhesive, and by brazing. It is clear that the bonded beam had a damping level only just above that of the brazed beam and it was much less than the beams which could rely on friction at their joints. 

Saito H, Tani H (1984) Vibrations of bonded beams with a single-lap adhesive joint. J Sound Vib 92 299-309... 

Table 13.2 Comparison of Weight, Stiffness, and Strength for Bonded Beams...

As expected, the bonded beam had lower stiffness and natural frequency than the welded beam, this no doubt being due to the lower shear modulus of epoxy resin (18-5 N/mm) with respect to mild steel (114 N/mm). However, by bonding two pairs of small ribs to the base end of the bonded beam, in the manner shown in Fig. 1.8(b), the... 

Fig. 1.8. Welded/bonded beam without stiffeners (a) and modified bonded beam with stiffeners (b).

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