Bottom steel slab

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. 

Figure 16. Shallow surface crack at the outer radius of a sharp V2T bend on 80,000 psi steel sheet (top). Corresponding subsurface concentration of REM oxysulfides and sulfides in a slab cross section near the surface. The parent ingot was treated with 5 lbs of rare earth silicide per ton of ingot steel (bottom). The bottom picture is from a Baumann print or sulfur print, not sensitive to the oxides and thus eliminating the argument of reoxidation as main cause of surface defects in REM treated steels. Magnification, 2.5X-...

Alumina electrolysis cells consist of a rectangular steel shell lined with a 25-35 cm layer of baked and rammed dense carbon, which provides both chemical resistance and the cathode contact with the electrolyte via steel bus bars imbedded in the carbon. Normal lining life is 4—6 years, after which it is replaced as large preformed slabs. Once a reduction pot has been started the bulk of the cathode current to the carbon lining is via the pool of newly formed molten aluminum in the bottom of the cell (Fig. 12.2). 

The temperature produced in the steel by th is, heat production is highest in the bottom thermal shield and in the. east side wall with slab loading. With the present design of the shield (see Section 2.5.1).and air flow of 25,000. cfm, it is estimated that, the maximum steel temperature in the bottom shield will not exceed the air temperature by more than 150°F at 60,000 kw operation. Furthermore, the maximum temperature of the steel next to the concrete will be less than 70 F above the air temperature. 

The bottom heat insulatitHi layer of reduction cells is composed of diatomaceous (moler) bricks, vermiculite slabs, perlite bricks, and calcium silicate boards. To smooth the surface of the bottom of the steel cradles, sometimes people use fireclay grit (grain). 

Usually, the lining (repair) of a reduction cell is performed in a specialized repair shop rarely, it is made right in the reduction shop. Typically, a thin layer leveling the granulated fireclay grit is placed in the new steel cradle or in the cradle after repair, and then the heat insulation slabs are lined. On the layers of heat insulation the refractory barrier layer is lined (bricks or dry barrier mixtures), the side line is made near the edges, and the cathode bottom blocks are installed. There are no mortars between the insulation layers. Bricklayers try to avoid using mortars because excessive water requires evaporation, which is not an easy process. Sometimes mortars are used to Une the upper layer of bricks (if the refractory layer is made from bricks). The carbon ore SiC side-wall blocks are installed on the side line after the cathode bottom blocks have been installed. 

Four-node-layered shell elements representing the concrete slab. Reinforcement layers comprising steel material properties should be used to simulate the steel reinforcement located at the top and bottom of the concrete slab. 

Type 6. Tanks without steel floors supported on a concrete slab. Wall-to-slab connection details shall be in accordance with the manufacturer s recommendations. Installation of the foundation, bottom tank ring, and sealing of the tank wall to the slab shall be the responsibility of the general contractor or owner. 

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