Building Construction Illustrated: Francis Ching

Fernandez_Andy_ARCH1231_201901_Montgomery_Module 3_Summary #6_20190320

 

Wood: is a renewable building material that can be easily cut and dimensioned to support a wide range of structural loads. Lumber (wood cut into dimensioned sizes for specific uses) is used as boards, dimension lumber, structural lumber and timbers. Each has its own strength and load requirements. Although wood has its own natural defects (warping, moisture susceptibility and knots) it excels in tension and compression as a structural element. All wood elements such as beams, subflooring panels, joists and posts must be carefully laid out within proper spacing of other members for load bearings.

Wood beams must be spaced between 4’-8’ and be supported by timber, steel or concrete columns. Diagonal bracing and bridging must be used to avoid rotation at intervals in framing. All loads are evenly distributed with the use of a grid system that superimposes all supporting partition and load bearing elements. Wood planks are used as diaphragm reinforcement. Connections used with wood members involve steel plates, bolts, nails, metal straps, brackets and split rings (timber). Some wood elements can be left exposed for its beauty.

Masonry: Masonry brick and glazed tiles are used extensively in cladding on the building envelope. Structural clay tiles are glazed tiles used in areas of heavy wear, moisture problems, strict sanitary requirements, walls and partitions. Different wall thicknesses can be constructed, including cavity walls. Brick is also used for cavity walls, particularly using the running bond method. Standard brick walls can used Common, Flemish, Stack or Garden bonds for decorative patterns.

Steel: Steel is used in a manner like wood framing but with greater strength and no cutting. Steel beams are connected using angles, stiffer plates, bolts and welds. Each contribute to shear or moment resistance. The strength of a connection depends on the sizes of the members used.

Concrete: Concrete beams must be reinforced with steel β€œRe-Bars” embedded 2” from the surface of the concrete to avoid corrosion. Concrete beams must have reinforcement at the ends connected to the columns, at the bottom across the beam to deter sagging (tension moment) and at the middle top of the beam to prevent a negative bending moment. Concrete columns must also be reinforced with either rectangular or spiral steel inside running along its height to resist bucking. Splices can be used to extend the height of rebar within the columns. All reinforcement steel must start at foundation level and end at the top of column. Columns are laid out in a rectangular grid. Concrete columns can also support timber or steel beams. Precast Concrete slabs, beams and tees can also be used. Advantages of precast elements are less depth, reduced weight and longer spans. These units have a better quality finish and structural integrity.

 

CHAPTER 8: Among the best building materials is brick. Brick is fire resistant, comes in many colors and is modular (can fit on a human hand). Brick walls can be used along or as composite walls (brick veneer walls with CMU unit as a back up wall). Brick walls can also be reinforced with grout and steel re-bars. Bricks also are made with hollow cores to add grouting and reinforcing steel. Brick elements find uses as curtain walls, cavity walls and decorative walls. Many different patterns of courses can be used with brick walls. The most common, used for cavity walls for its shorter depth is the running bond method. The mortar joints in brick walls play a crucial function to bond the units together and keep water and wind out. Joints are usually 3/8” and Mortar comes in various colors to add to the appearance of the overall wall design. Mortar also comes in various types of strengths, from high strength to low, depending its use and location. Brink lintels can have steel angles, reinforced cement grout or precast reinforced concrete lintels. Brick lintels can span from 4’ to 6’. Brick arches can also be produced. Buildings normally have thicker walls at the bottom and thinner brick wall at the top for load support distribution.