Chapter 2 Flashcards
Types of Loads?
Live, Rain and Snow, Wind, Seismic , Lateral soil pressure
Dead Loads
The combined weigh of all the permanent components of the building
Live Loads
Nonpermanent loads caused by the weight of the building
Rain and Snow loads
Act downward on roofs
Seismic Loads
Highly dynamic horizontal and vertical forces caused by the motion of the ground
Lateral soil pressure
Horizontal pressures of the earth and groundwater against basement walls
Horizontal thrusts
Originate from long span architectural components like arches and domes
How do foundations on bedrock settle?
They settle a very little amount, they are designed to limit settling to millimeters or fractions of inches.
Uniform Settling?
When settling happens at the same rate throughout the building.
Differential Settling ?
When parts of the building settle at different times, this can lead to distortion of the building frame and cracks
Most foundation failures can be contributed to ?
Differential settling and gross settling which is where the soil below ground completely fails.
How are earth materials classified?
They are classified by particle size, the presence or organic content and sensitivity to moisture.
What is consolidated bedrock?
A contiuous mass of mineral materials that can only be removed by drilling. It is usually the strongest and most stable material that a building can be built on.
What is soil?
Any earth material that is particulate.
Soil Classification ?
Boulders, Cobbles, Gravel, Sand, Silt , Clay.
Gravel and Sand are also called?
Coarse Grained Materials.
Silt and clay is also called?
Fine Grained Material
If the particles are too small to see to the eye it is…
Silt or Clay
What is shear strength?
The resistance to internal sliding
Coarse Grained materials…
-Densely packed, exhibit high strength and can support greater loads, but when coarse grained soils are not densely packed less load can be supported.
Soils that rely on internal friction are called
Frictional or Cohesionless
Soil Liquefaction
When water saturated sands or soilts lose all of their strength when a large change in load happens, like in an earthquake.
Clay particles are
Extremely small in size and flatter in shape and can combine with each other to form fabrics.
Clay Soil is cohesive because?
They can stick together and during an excavation in clay soil can be done without temporary support
Cohesionless soil ?
Sand, must be excavated at a shallower angle to avoid the collapse of unsupported walls.
Why can cohesive soils sustain a higher moisture content ?
Because they have a higher liquid limit.
Are clay soils expansive?
Yes, they are prone to expand or contract with changes in moisture content. This means that water can pass through clay very slowly or not at all.
What is Gradation ?
The range of the particle sizes present.
Well Graded Soil?
A broad well districbuted range of particle sizes
Poorly Graded Soil
Consists of particles more limited in size.
