Table 9.2 was used to select the formwork system for the exterior ‘‘wall.’’ The selection was a self-raising form for the following rea­sons: 1. The self-raising form is suitable for buildings higher than 25 stories. 2. It can accommodate architectural concrete requirements. 3. The self-raising form is a crane-independent system which is suitable for restricted […]

The Tabor Center is a 1.3 million ft2 (120,000 m2) [20,000 ft2 (1860 m2) per floor] multi-use facility in the center of downtown Denver. It consists of twin office towers of 32 and 40 stories. The tower structure is composed of three elements: the exterior wall, the cen- ^^v^Formwork systems Influence factor Conventional column/ wall […]

When deciding to use a special forming technique, the contractor has to evaluate his or her own in-house expertise, which includes trouble-shooting experience and safety management. For exam­ple, in vertical forming systems such as slipform and self-raising forms, the in-house experts have to deal with special problems such as leaking hydraulic equipment, leveling of the […]

An important factor that influences the selection of the formwork system is the availability of crane time. Crane time is defined as the time in which the crane is engaged in raising and lowering construction materials and tools. In congested site conditions where installing more than one crane is difficult, the limited crane time available […]

As previously indicated in Chapter 5, most of the ganged formwork systems (i. e., jump form, slipform, and self-raising formwork) re­quire high initial investment and intensive crane involvement. However, high repetitive reuse can make these systems economi­cally competitive. Availability of capital investment is a must for utilizing these systems.

Vertical forming systems are sensitive to weather conditions. Typi­cally, in vertical forming systems, the newly placed concrete is sup­ported by the wall already cast below it. The lower wall section must gain sufficient strength to support the fresh concrete above. The rate of strength gain for the lower wall is influenced by ambi­ent temperature, moisture […]

The nature of the job, including local conditions, is one of the pri­mary factors in formwork selection. Some of the factors that should be considered are explained below. Area Practice Area practice has an important impact on the selected formwork system. This influence is evident in slipform operations which are highly labor intensive and usually […]

The most important advantage of using a sophisticated formwork system is the speed of construction. The speed of construction affects cost because it determines the time when the building will be available for use and also reduces the financial charges. The major factors that determine the speed of construction follow. Floor Cycle. Faster floor cycle […]

Surface quality and appearance are always referred to as the con­crete finish. Concrete surfaces can be classified as rough finish ‘‘as-cast surface,’’ smooth exposed, covered (with a special clad­ding material or painted), or textured (with an architectural sur­face texture and treatment). As-cast concrete finish typically shows some irregularity on the surfaces and may contain some […]