Design of reinforced concrete structural frames
There are three basic considerations in constructing a structural frame at the casting site. One is the actual construction and construction of forms of the required size, shape and strength. Next is the proper placement of the steel rebar needed for reinforcement. Finally, the support of the formwork must be considered and the concrete placed through appropriate shoring until the concrete has gained sufficient strength to support itself.
The size and shape of the members you formed are indicated on the building plans, while the size and amount of material needed to make the forms strong enough are based on the loads and pressures involved. The size, shape and amount of steel required are also indicated on the drawings in the form of columns, frames and beams.
Columns shape
Column forms are often subject to much greater lateral pressure than wall forms due to their comparatively small cross section and relatively high placement rates. Therefore, it is necessary to provide tight joints and strong lashing support. Some means of accurately locating column shapes, anchoring them at their base, and keeping them upright are also critical considerations.
The columns can be square, rectangular, round or irregular; and the shapes can be made of wood, steel or fiberboard. Wood (boards or plywood) is commonly used for square or rectangular shapes and can also be used for irregular or round shapes. However, most round columns are formed by using steel tubes or fiber panels of various diameters. Steel shapes are also available for square or rectangular columns.
As the column size increases, the thickness of the casing should be increased or vertical stiffeners should be added to prevent casing deflection. vertical rigidity is used. Also note the adjustable metal clamps that hold the form together. There are several methods for linking column forms, and some are illustrated in Figure 8-9. Ties of this type are usually called yokes.
Columns reinforcement
Reinforcing steel in columns consists of two parts: the longitudinal bars that run the length of the columns and the lateral reinforcement that encloses the longitudinal steel. When load is applied to a reinforced concrete column, the longitudinal bars absorb a portion of the load. Consequently, each bar acts as a small, thin column susceptible to buckling within the concrete shell. Lateral reinforcement, which is in the form of horizontal joints or a spiral, provides lateral support and maintains proper spacing and alignment of longitudinal bars.
Beam shapes
Las columna y vigas en cada piso de una estructura de marco de hormigón armado generalmente se colocan monolíticamente, lo que significa que las formas deben enmarcarse entre sí. También es importante recordar que algunas partes de estos formularios pueden eliminarse antes que otras. Por ejemplo, los lados de la viga se pueden quitar primero, seguidos luego por las formas de las columnas, y finalmente por los fondos de la viga . Por lo tanto, es necesario construir las formas de viga para que cada parte se pueda quitar sin alterar el resto de la forma.
Spandrel beam shape
Forms for spandrel beams (deep beams spanning openings in exterior walls) must be formed carefully. Form alignment must be precise to produce an attractive wall. The edge heads often extend on the outside to accommodate the knee pads used to keep the forms aligned.
Reinforced beam
El refuerzo de acero en vigas tiene tres propósitos: (1) proporcionar resistencia a la tracción a esa parte de la sección transversal de la viga que sufre tensión debido a una carga aplicada, (2) para agregar resistencia a la compresión a la porción de la. sección transversal de la viga que está en compresión y (3) para proporcionar resistencia al corte adicional a la sección transversal de la viga.
Tension and compression bars can be straight or bent and are held in alignment by vertical bars that also resist shear. The entire assembly rests on chairs located at the bottom of the form. To ensure that the reinforcement does not move during concrete pouring, the bars are held in position within the formwork by securing them to the formwork braces.
