Composite Slabs

Consider a composite wall made of three parallel slabs of cross-sectional area A (Fig. 2.3), The thickness and thermal conductivity of these slabs are 13 and k, respectively. Heat is transferred from a hot fluid at temperature 7 through this composite wall to a cold fluid at temperature To- Coefficients of heat transfer on the hot and cold sides are hi and ho, respectively. 

Electric analogy or the five-step formulation elaborated in Ex. 1.7 readily leads to 

Actually, there exists a thermal resistance, the so-called contact resistance, through each interface of a composite structure. This resistance depends on the contact pressure, the roughness of two surfaces, and the fluid in which these surfaces are pressed together. For more information on the subject the reader is referred to Reference 6 (and the references cited therein). 

For a boundary system (Step 1) at the interface of two plates (Fig. 2.4), the first law of thermodynamics (Step 2) yields 

With Fourier s conduction and Newton s cooling laws (Step 3), expressing q and q2 now in terms of total (conductive plus convective) resistances over the temperature drop Tm — T , on both sides, we have 

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Eye protection — safety glasses or goggles - is mandatory whenever any pyrotechnic composition is being prepared or tested. Necessary equipment includes a mortar and pestle, a laboratory balance, a soft bristle brush, several 2-3 inch lengths of fireworks-type safety fuse (available from many hobby stores), and a fireproof stone or composite slab on which to conduct burning tests. 

When a fluid is present in contact with each solid wall, there will be an additional resistance to heat transfer in each fluid boundary layer or film . The combined mechanism of heat transfer from a hot fluid through a dividing wall to a cold fluid has many similarities to conduction through a composite slab reviewed earlier. 

One side of a copper block 4 cm thick is maintained at 175°C. The other side is covered with a layer of fiber glass l.S cm thick. The outside of the fiber glass is maintained at 80°C, and the total heat flow through the composite slab is 300 W. What is the area of the slab ... 

Materials of different thermal conductivity are frequently used in adjacent layers to provide thermal insulation. Consider a flat composite slab made of layers as shown in Figure 7.25. The heat flux through each layer and the... 

Figure 7.25 Temperature profile for heat transfer through a composite slab.

Carbon fiber reinforced mortar has been used for composite slab construction [213]. Sakai et al [214] have used a cfrc for curtain walls, providing adequate wind resistance with higher fatigue strength than ordinary concrete. 

Bayasi MZ, Zeng J, Composite slab construction utilizing carbon fiber reinforced mortar, ACI Structural Journal, 94(4), 442-446, 1997. 

A steel-conerete composite slab is newly available in construetion, of which concrete is placed in a steel mold that eonsists of steel side plates, top reinforcing bars and transverse ribs, and stud-planted bottom steel plates. Configuration of one t) e slab is shown Fig. 13.21. Compared with a reinforced concrete slab, this slab is expeeted to bear a large load- capacity and to have good enduranee. Although these eharacteristics are favorable for bridge construction, visual inspection is very difficult in particular, for concrete and its interfaee with steel plate. As a result, effective inspee-tion techniques for steel-concrete eomposite slabs are in demand and under development. 

Fig. 13.21. Robinson-type of steel-concrete composite slab.

Itoh T, Shigeishi M, Ohtsu M (2002) Acoustic emission in fatigue process of steel plate-concrete composite slab. Progress in Acoustic Emission 11 132-137... 

The calculation of heat flow along a lagged bar, as shown in figure 4.2, involves a straight-forward application of the above equation. The composite slab problem is more interesting. Suppose we have two slabs of equal area A, thicknesses q and l2, and thermal conductivities and ki respectively. Let the temperatures be defined by figure 4.3. 

Structural timber-concrete composites (e.g., timber-concrete composite slabs and timber wall-concrete deck composite in which the connection between the two common constmction materials is made through a bonded joint). The aim is to replace traditional mechanical fasteners by an adhesive connection, which has several advantages in comparison with the former for instance, a bonded joint is able to distribute the applied load over the entire bonded joint area, resulting in a more uniform distribution of stress (compared to mechanical point connections), requires little or no damage to the adherends, adds very little weight to the structure, and has a superior stiffness and fatigue resistance. 

If there is a diaphragm in the structure, as, for example, is the case with the composite slab of the loft in the prototype building, it is recommended to avoid the more complex option of modeling it with shell elements and instead create a master node that will be connected with all nodes of the diaphragm (Eig. 21). In this case, in order to account for uncertainties in the location of masses and in the spatial variation of the seismic motion, the calculated center of mass at each floor shall be considered as being displaced from its... 

Chou C, Tsai K, Yang W (2009) Self-centering steel connections with steel bars and a discontinuous composite slab. Earthq Eng Struct Dyn 38 403 22. doi 10.1002/eqe. 

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