Several types of joints may occur or be formed in concrete structures: Construction joints are formed when fresh concrete is placed against hardened concrete. Expansion joints are provided in long components to relieve compressive stresses that would otherwise result from a temperature rise. Contraction joints (control joints) are provided to permit concrete to contract during …
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Curing of concrete consists of the processes, natural and artificially created, that affect the extent and rate of hydration of the cement. Many concrete structures arecured without artificial protection of any kind.They are allowed to harden while exposed to sun, wind, and rain. This type of curing is unreliable, because water may evaporate from the …
Mixing and placing concrete at a high temperature may causeflashset in the mixer, during placing, or before finishing can be completed. Also, loss of strength can result from concreting in hot weather . In practice, most concrete is cast at about 70 20F. Research on the effects of casting temperature shows highest strengths for concrete …
Frozen materials should never be used. Concrete should not be cast on a frozen subgrade, and ice must be removed from forms before concreting .Concrete allowed to freeze wet, before or during early curing, may be seriously damaged. Furthermore, temperatures should be kept above 40 F for any appreciable curing (strength gain) for the concreting …
Contractors should understand the process of rebar inspection , whether the inspection is done by their own forces or by an inspector re p resenting the owner or building official. The goal of inspection or quality – control programs is to ensure that contract documents and buildingcodes are followed. The programs also ensure structural safety …
Currently, open-web steel joists are still relatively small, parallel-chord trusses, but hot-rolled steel shapes usually make up the components of design of open web steel joist . (For a time, cold-formed steel shapes were preferred for chords to utilize higher working stresses available in cold-formed sections of ordinary carbon-steel grades. Unfavorable fabrication costs, however, led …
In general, all types of beam connections are classified as either framed or seated. In the framed type, the beam is connected to the supporting member with fittings (short angles are common) attached to the beam web. With seated connections, the ends of the beam rest on a ledge or seat, in much the same …
Design of bracing to resist forces induced by wind, seismic disturbances, and moving loads, such as those caused by cranes, is not unlike, in principle, design of members that support vertical dead and live loads. These lateral forces are readily calculable. They are collected at points of application and then distributed through the structural system …
There are many different types of foundation excavations performed during the construction of a project. For example, soil may be excavated from the cut or borrow area and then used as fill . Another example is the excavation of a shear key or buttress that will be used to stabilize a slope or landslide. Other …
A shallow foundations are often selected when the structural load will not cause excessive settlement of the underlying soil layers. In general, shallow foundations are more economical to construct than deep foundations. Common types of shallow foundations are listed in Table 6.2 and described below Spread Footings, Combined Footings, and Strip Footings. These types of …