Features of Structures

Features of Structures Before building a structure architects and ________________ need to figure out every detail of the ________________ in advance. There are four especially important _______________ to consider: ________________, ________________, ________________, and ________________. engineers design features function shape materials joints

Function __________________: Before building a structure, we need to think about what the thing is supposed to do. Most structures have ______________ functions. For example… __________________: _______________________________________________________________________________________________________________________________________________________________________________________________________________________   several A bridge - its job is to support vehicles and people - but the steel and concrete used to make the bridge can weigh much more than the vehicles and people that cross  so a very important function of any structure is to support its own weight

Function (cont) functions water perspiration cloth Designers have a hard time creating structures that perform all of their ________________ equally well. For instance, plastic-covered running shoes keep the _______________ out when you run through a puddle. But they also keep _________________ in, so your feet could get hot and sweaty. Designers try to compromise. Most running shoes have rubber and plastic soles and ________________ uppers. functions water perspiration cloth

Shape rectangular squish load forces joints collapse weaknesses Square and __________________ frames are easy to build and designers like to use them. However they also ______________ when a ______________ presses on them. Enormous ________________ develop at the ______________ and the frame is likely to ________________. Designers have come up with ways to overcome these __________________. rectangular squish load forces joints collapse weaknesses

Problem 1 Braces ties gussets triangles Rectangular frames can easily be pushed and pulled out of shape. Solution: _________, _____, and ________ turn rectangular corners into rigid ________________, able to resist large forces. Braces ties gussets triangles Braces Gussets Ties

Problem 2 braces arches double cantilever ground Frames made of vertical columns and horizontal beams are weak in the middle. Pressing down on the middle causes the beams to push the columns out and the frame to collapse. Solution: Use ___________, __________, or a ____________ ________________to spread forces evenly through the whole structure and down to the ______________. braces arches double cantilever ground Brace Arch Double Cantilever

Problem 3 cylindrical less thinner load Solid, four-sided beams use a lot of building materials and are very heavy. Solution: Use __________________ columns, which are harder to build but use ____________ material. Or make the beam or column ________________ in places that carry less ____________. cylindrical less thinner load I-Beam T-Beam Box Beam

Cardboard (corrugated) Problem 4 Plywood, cardboard and other building materials are made in flat rectangular sheets. When a load presses on the middle or the sides are compressed together, the sheet bends out of shape. Solution: Make the material out of ______________ (laminations) that are ____________ or pressed together. Arrange the layers so that they ________________ each other. layers glued strengthen Cardboard (corrugated) Plywood

Materials structure combined Reinforced composite tension compress The properties of the materials must match the purpose of the ______________. Different materials can be _____________ to give the exact properties you need. ________________ concrete is called a ________________ material. Steel rods and cables can support very strong ______________ forces but they bend and twist if you ______________ them. Concrete resists large ________________ forces, but breaks if it is ______________ or ________________. If they are combined they create a much stronger material. structure combined Reinforced composite tension compress compression pulled twisted

Joints How a structure is ________________ together is an important ______________ because structures are often ______________ where their parts are joined together. fastened decision weakest

Joints (cont) Mobile Joints: ________________________________________ Examples: ________________________________________ Rigid Joints: Joints that allow movement door hinges, elbows, pins in a bike chain Fasten parts firmly together nails, screws, bolts, tape, glue, zippers

Joints (cont) All joints can fit into five groups: Fasteners (nails, staples, bolts, screws) Ties (thread, string, rope) Adhesives (glues, sticky substances) Melted joints (pieces of plastic or metal melted together) Interlocking joints (carefully shaped parts that hold themselves together, ex) Lego)