Compression- crushing brick like we have done already *A fired brick has twice the strength of an unfired brick.

Bending moment (transverse strength)- example-window opening. Support the brick on two sides so that it is suspended in middle. Apply point load in direct center of brick. Measure maximum load it can take.

Shear (earthquake load)- examples-cantilever system, arch. Pull two sides apart past each other. Measure force required to do this.

Wind- maximum to design for in Lawrence, KS is 70-80 mph. Find equivalent load in psi to find pressure. Test brick at this pressure horizontally. The windward side of the wall takes the most load. Design for maximum.

Point- example-beam resting on wall. Another example of a compressive force. Same as test we have already performed for compression.

Dead — example-bricks themselves resting on top of each other. This is another example of a compressive force. To design a brick for dead loads you need to know how much weight will be resting on it. This includes the density of the material, how many bricks will be above it. This is found by knowing the height of the building, the height of a brick, and the area of the wall. Included in dead weight is the weight of the roof- the live load plus the dead load. You must design for the maximum condition, ie. the brick at the bottom of the wall.

Torsion- twisting stress

Hardness and resistance to abrasion

Effect of wetting

Temperature

Four physical properties that must be considered if a clay is to considered suitable for a brick: 1. Plasticity- property by means of which clay forms a plastic mass when mixed with water and molded into a shape and retain that shape 2. Shrinkage 3. Tensile strength- the quality of the clay which resists the tendency of the clay to rupture 4. Fusibility- property of clay which allows it to become hard when heated.

Assembly

Types of assemblies:
·Curtain and panel wall
·Parapet walls
·Copings
·Pilasters and buttresses
·Chases and recesses
·Sills and frames
·Solid walls
·Hollow walls
·Rolok-bak walls
·All-rolok common bond
·All-rolok Flemish bond
·Cavity walls

Factors affecting compressive strength:
·Strength of single unit
·Geometry of unit
·Strength of mortar
·Deformation characteristic of unit and mortar
·Joint thickness
·Suction of units
·Water retentively of mortar
·Brickwork bonding
·Workmanship

Entire system

Loads acting upon an entire system:
·Dead- arises from weight of structure and all the materials attached to it
·Live- user or occupancy loads
·Snow- acts directly on roof. Design for 20-25 lbs/sq. ft in KS
·Wind- multiple factors affect this loading. Shape of building, surface conditions, elevation of building, openings in the wall, gust factor (ht. and exposure) 70-80 mph ·Earthquake- design for zone 2A in KS ·Water and Earth- for below ground conditions only.

Tests

Figuring the Approximate Total Load for a Structure

Objective: To design an entire structure of soil cement bricks, it seems critical to figure the approximate total load that the structure will have. Five to seven loads affect a structure. These are dead, live, snow (only in some locations), wind, earthquake (only in some locations), water and earth. While all of these loads can be found and accommodated for, it would be unrealistic to add up all of the individual loads that act upon a structure and design for this amount. It would result in a huge over design and not economical in the least. For example, you would not have 100 people in the house during a snowstorm that accumulated 25 lbs/sq. ft. of snow with 80 mph winds while at the same time an earthquake is occurring. Instead, you design for the worst-case scenario with specific combinations of loading; 100 guests during an earthquake would be acceptable.

Methodology: Using specific calculations and tables, the individual loads can be found or closely estimated.

Equipment: calculator, tables, known equations

Expected results: Using the given equations, each individual load can be approximated as accurately as possible. The maximum values of rational combinations of loads can be analyzed to determine

Potential problems: This is just an estimated assumption. Like all estimations, there will be a certain degree of error. There is no real way to find out if your calculation is correct or not. First, this is a theoretical structure. Second, even if it was built, you cannot weigh certain members to obtain exact data. It would also be impossible to consider every single load because some will surely arise that you did not think of. Another problem arises in obtaining data from a table. Sometimes the table does not list a value for your particular situation or characteristic. You must estimate between two and this will not yield and accurate amount.

Deliverable products: Using the estimated maximum values obtained for each load, rational combinations can be analyzed to determine the amount of loading the structure could possibly have during a given scenario. This data would most certainly aid in design of the structure.

Testing for Resistance of Wind Loads

Objective: One of the types of forces that acts upon a brick in a wall assembly of a structure is a wind load- the force applied upon the brick as a result of the blowing wind. In Kansas, this is an important design factor because of the climate. Guidelines are in place requiring that you design a structure in Kansas to allow for 70-80 mph winds. A structure and its components obviously must be able to withstand this pressure.

Methodology: The design wind pressure value can be obtained by using a formula and various tables. First, we need to obtain that value for our brick. Using that psi value, we test our bricks, applying that particular load along the side in which the wind will be affecting them. We can do this in the same method as used earlier in the class, provided that the psi value established is not too large for the machine to handle. We do not need to know the maximum force the brick can take, simply whether or not they can withstand the wind load.

Equipment: Wind load formula, calculator, test bricks of various soils and soil/ cement mixtures, some type of compression device

Expected results: By applying the amount of pressure to our bricks that would be equivalent to an 80 mph wind, we will obtain whether or not each tested brick can withstand that velocity of wind, and thus work for our structure. Maybe all the bricks will be able to resist the load and that is OK.

Potential problems: Problems would be ones that arose from using the imprecise machine to compress the bricks. An eccentric loading of the brick would not provide an accurate pressure from brick to brick. Also, the amount of cracking that may occur in a brick is not measurable. The only results we obtain would be total failure of a brick.

Deliverable products: The type of soils and soil cement mixtures that do not completely fail in 80 mph winds.

Testing Shear Force

Objective: One type of force that occurs upon a single brick in a wall is the shear force. Shear force is the force that acts upon a body in parallel lines or planes. It is the force that causes a brick to break through its shear center. Many times this is produced in a wall by the action of wind or other forces on adjoining perpendicular walls. Other possible times when this type of shear might occur is in an Earthquake. Possible examples of bricks that endure more shear than others would be bricks in cantilevers and arch construction.

Methodology: To determine the shear force that our bricks are capable of withstanding, we can create an experiment that causes forces to act through the brick. Unlike the compression test that we did earlier, to test shear force we need to determine a way to hold half of the brick fixed, and then apply a load vertical through the other half. So we can pull two sides apart past each other.

Equipment: A vise can be used to hold the brick in a vertical direction, and then a load can be applied through the brick by placing a strap across the top of the brick and then weight can be added to the brick through use of a bucket full of sand or weights.

Expected results: By applying the force to our bricks, which would be equivalent to between 50-200 lbs/sq in. The range normally expected for most standard bricks is between 100-300. From this we will obtain whether or not each tested brick can withstand the shear force. Maybe all the bricks will be able to resist the load. However it is quite unlikely that their shearing strength will be an important consideration, since the shearing strength of brick ranges from three to six times the tensile strength, and the likelihood of a brick failing in direct shear is quite remote.

Potential problems: Problems would be ones that arose from using the imprecise machine to compress the bricks. An eccentric loading of the brick would not provide an accurate pressure from brick to brick. Also, the amount of cracking that may occur in a brick is not measurable.The only results we obtain would be total failure of a brick.

Deliverable products: The type of soils and soil cement mixtures that do not completely fail.

Testing Bending Moment

Objective: Another factor to consider in the structural design of a brick is the Bending moment (transverse strength). This is a bricks resistance to a load when the brick acts as a beam supported at both ends. This is usually expressed as a modulus of rupture. The type of moment that occurs upon a single brick in a wall is usually due to load above it. This can be seen in typical construction in window openings or in locations where a point load is placed on a brick in its center.

Methodology: To determine the Bending moment that our bricks are capable of withstanding, we can create an experiment that causes moments to act through the brick. Unlike the compression test that we did earlier, to test the moment we need to determine a way to cause an internal moment in the brick. One way to do this to place to vertical forces on each of the two ends, and then apply a force through the center of brick which will cause an internal moment in the brick. This is typically similar to causing the upper portion of the brick to be in compression and the lower part to be in tension.

Equipment: Two stands are needed to hold the brick up one on each end and allow an opening of space underneath the brick in a vertical direction. Then a load can be applied through the center of the brick this load must be a point load. This point load needs to be created using a press or a strap whose force is not over the entire surface of the brick. Or another way to establish moment is to but the brick in a vise and tighten the brick so that the load are applied more accurately to what an actual moment is. The only difficulty to this would be determining the amount of force the vise is exerting.

Expected results: By applying the transverse moment to our bricks, we would hope to come up with value near that normally expected for most standard bricks is around 500 lbs/ sq. in. From this we will obtain whether or not each tested brick can withstand the bending moment. Maybe all the bricks will be able to resist the load. However it is quite unlikely that most will fail this test at much lesser values of psi since the bottom of the brick is not support.

Potential problems: Problems would be ones that arose from using the imprecise machine to exert the moment to the bricks. An eccentric loading of the brick would not provide an accurate pressure from brick to brick. Also, the amount of cracking that may occur in a brick is not measurable. The only results we obtain would be total failure of a brick. Also this may not be the most accurate way of testing bricks since it isn't exactly the same as a moment. And therefore the value won't be as large as expected.

Deliverable products: The type of soils and soil cement mixtures that do not completely fail.

Bibliography

Benjamin, B.S. Statics, Strengths and Structures for Architects. Lawrence, KS: Ashnorjen Bezaleel Publishing Company, 1984.

Hibbeler, Robert C. Structural Analysis. New Jersey: Prentice, 1999.

Plumber, Harry C. and Leslie J. Reardon. Principles of Brick Engineering. Washington, D.C.: Structural Clay Products Institute, 1943.