Economy can be obtained by designing joists and slabs so that the same-size forms can be used throughout a project. It will usually be advantageous to use square-end forms for interior spans and tapered ends for end spans, when required with a uniform depth. TABLE 9.19 Temperature and Shrinkage Reinforcement for One-Way Joist Construction Top-slab thickness, in Required area of temperature and shrinkage reinforcement, in2 Reinforcement Reinforcement weight, psf 31/2 0.076 No. 3 bars @ 171/2 in 0.26 4 0.086 No. 3 bars @ 15 in 0.30 41/2 0.097 No. 3 bars @ 131/2 in 0.33 5 0.108 No. 3 bars @ 12 in 0.38 51/2 0.119 No. 3 bars @ 11 in 0.41 Fire Resistance. Table 9.17 gives minimum top-slab thickness for fire resistance when a fire-resistant ceiling is not used. Temperature and Shrinkage Reinforcement. This reinforcement must be provided perpendicular to the ribs and spaced not farther apart than 5 times the slab thickness, or 18 in. The required area of Grade 60 reinforcement for temperature and shrinkage is 0.0018 times the concrete area (Table 9.19). For flexural reinforcement, see Art. 9.56. For shear reinforcement, see Art. 9.57. Embedded Pipes. Top slabs containing horizontal conduit or pipes that are allowed by the ACI 318 Building Code (Art. 9.53) must have a thickness of at least 1 in plus the depth of the conduit or pipe. Bridging. Distribution ribs are constructed normal to the main ribs to distribute concentrated loads to more than one joist and to equalize deflections. These ribs are usually made 4 to 5 in wide and reinforced top and bottom with one No. 4 or one No. 5 continuous rebar. One distribution rib is usually used at the center of spans of up to 30 ft, and two distribution ribs are usually placed at the third points of spans longer than 30 ft. Openings. These can be provided in the top slab of one-way concrete joist construction between ribs without significant loss in flexural strength. Header joists must be provided along openings that interrupt one or more joists. Reinforcement required for strength can be determined as indicated in Art. 9.46, by treating as a beam a section symmetrical about a rib and as wide as the spacing

Rimmed or capped steels cannot be produced if too much carbon is present (0.30% or more), because insufficient oxygen will be dissolved in the steels to cause the rimming action. Killed and semikilled steels require additional costs for deoxidizers if carbon content is low, and the deoxidation products form nonmetallic inclusions in the ingot. Hence, it often is advantageous for steel producers to make low-carbon steels by rimmed or capped practice, and high-carbon steels by killed or semikilled practice. Pipe, or shrinkage cavities, generally is small enough in most steels to be eliminated by rolling. Blowholes in the interior of an ingot, small voids formed by entrapped gases, also usually are eliminated during rolling. If they extend to the surface, they may be oxidized and form seams when the ingot is rolled, because the oxidized metal cannot be welded together. Properly made ingots have a thick enough skin over blowholes to prevent oxidation. Segregation in ingots depends on the chemical composition and on turbulence from gas evolution and convection currents in the molten metal. Killed steels have less segregation than semikilled steels, and these types of steels have less segregation than capped or rimmed steels. In rimmed steels, the effects of segregation are so marked that interior and outer regions differ enough in chemical composition to appear to be different steels. The boundary between these regions is sharp. Rimmed steels are made without additions of deoxidizers to the furnace and with only small additions to the ladle, to ensure sufficient evolution of gas. When properly made, rimmed ingots have little pipe and a good surface. Such steels are preferred where surface finish is important and the effects of segregation will not

In some instances, the client may request that the architect revise the original construction documents or prepare new drawings to reflect the as-built conditions. This is normally an additional service in the architect-client agreement. It should be made clear to the client that the architect, if brought into this process, is acting only in a drafting role, inasmuch as the as-built documentation, including dimensions and details, is furnished by, and is the responsibility of, the contractor. As-built and record drawings are helpful to the client in remodeling, maintenance, building-system modification, or making future additions to the project. The client should retain the drawings with maintenance manuals and operations procedures. It is advisable that the architect or engineer have follow-up interviews with the client and occupants of the building or tenant spaces to help ascertain the success of the project and learn where certain materials, details, equipment, or systems may be improved for future use in other projects. Good client relations demand this type of exchange. It is also helpful for the architect or engineer to disseminate the interview results throughout the office and professional community, to improve problem solving, design, and construction. Even in the best of relationships, disputes can arise between the client and architect, client and contractor, or architect and contractor, even though the architect and contractor do not normally have a written agreement with each other. Disputes should be quickly addressed and resolved for the well-being of the project and to minimize disruption of the design and building process. If the dispute cannot be resolved by the parties, various methods of resolution are offered that include settlement, mediation, arbitration, and litigation. To maintain insurance coverage and protect appropriate interests, proper notification to insurers or involvement of legal counsel is required. Settlement of Disputes. Disputes between two parties should be addressed quickly and, if at all possible, a settlement should be rendered and recorded. Settlement can be in the form of monetary adjustments or payments, free services on behalf of the architect to remedy or correct an error, or such other agreement between the two parties. It is recommended that this method of dispute resolution be used whenever possible to avoid time, cost, and anguish, which can occur as a result of mediation, arbitration, and litigation. Mediation. In mediation, the parties in dispute agree on a third independent party to act as a mediator and hear each sides position in the dispute in an attempt to mediate a resolution. Mediation is not binding on either party but helps resolve certain disputes due to a third partys focus on, and question of, the issues. Arbitration. This is a method of handling disputes in which an arbitrator or arbitration panel, often consisting of three members, is selected to hear the positions of the parties in the dispute and decide on a potential resolution. The resolution is binding on the parties. Cost and time for arbitration is usually, but not always, less than that required for litigation. The arbitrators usually consist of professionals (architects and engineers), lawyers, contractors, or other parties involved in the