MOCK UPS AND WIND MODEL TESTS BASICS AND CIVIL ENGINEERING TUTORIALS

MOCK UPS AND WIND MODEL TESTS BASIC INFORMATION
What Are Mock Ups And Wind Model Tests?


In addition to tests that are performed in the field, certain assemblies of buildings are mocked up at full scale and fully tested. This would be true for the assembles that are associated with curtain wall construction.

These mock-ups are required because it is extremely difficult to test in situ (on site when constructed). Also, it is more cost effective to check the assembly in the laboratory rather than finding a failure when the assembly is installed.

In addition, in the urban environment, wind loads on a building are impacted by other structures in the area. To account for this variable, a model of the building is created, along with models of the surrounding buildings.

These models are then tested in a wind tunnel. Sensors are placed on the building being tested and readings are taken of the pounds per square foot (psf) that would be imposed on the total outside surface of the building.

The wind tunnel loads that are used for testing are based on historical wind data of the area in question and requirements from the local code.

When a mock-up of the curtain wall is constructed (full scale) in a laboratory setting, it usually consists of a typical two-story curtain wall section of the building. Any unusual condition may have to be mocked-up for testing as well.

The mock-up assembly is tested to determine:

1. Amount of air and water infiltration observed
2. Drainage of the system
3. Structural capability of the mullions and glass
4. Expansion and contraction of the assemblies
5. Deflection of materials

Corrections are made to the mock-up, if required, so that all the assemblies are performing according to specified criteria. The components are then fabricated based on the results of the test.

Thus, the installation of the curtain wall should perform according to the standards established by the organizations. This eliminates the potential for failure that could have occurred and the consequence of replacement of the curtain wall if the mock-up was not tested in the laboratory.

FIELD FABRICATION OF STRUCTURAL COMPONENTS (MIXTURE AND COMPONENTS) BASIC AND CIVIL ENGINEERING TUTORIALS

FIELD FABRICATION OF STRUCTURAL COMPONENTS (MIXTURE AND COMPONENTS) BASIC INFORMATION
What Are Field Fabrication Of Structural Components?


Structural components that are fabricated on site by trades people constitute the greatest risk for a catastrophic failure. This is due to the fact that control of putting parts together in the field is not done with the same diligence and controlled environment as a factory-made component.

Thus, great care must be taken to ensure that proper testing is performed so that a failure will not occur. The erection of a concrete structure is an excellent example where the use of a mixed type material must have adequate testing.

Concrete is a very viable construction material if placed according to the standards established by the organizations. However, due to the complexity of mixing the ingredients at the plant and transporting it to the site, placing the concrete at the site requires numerous controls to obtain an excellent final product.

The testing of concrete should include:

1. A trial concrete mix approved by the owner’s engineer
2. Proper mixing procedures at the concrete plant
3. Timing for the transportation of the concrete mix
4. Designed and properly installed form work and shoring so that they will not collapse or deflect
5. Temperature monitoring of the concrete at the site (to make sure that flash setting will not occur)
6. Ambient temperature monitoring (too hot for flash setting and too cold for freezing)
7. Slump test to confirm water/cement ratio of the concrete
8. Supervision for concrete vibration and dropping height for the actual placement of the concrete
9. Monitoring the thickness of a concrete slab
10. Assurance that all the concrete encapsulates the reinforcing bars, especially when
pouring columns
11. Placement of a sample of the concrete into concrete cylinders to determine the compressive strength of the concrete at 7, 14, and 28 days (via testing in the laboratory). This will be accomplished for design strength conformance and to know when the forms can be stripped
12. Checking the number and location of the reinforcing bars required for the pour
13. Proper curing of the concrete
14. Assurance that reinforcing bars are properly lapped
15. Assurance that all exterior exposed concrete is covered by 3 inches of concrete
(2 inches for interior concrete) over the reinforcing steel

Even though steel sections are fabricated in a controlled environment at a plant, the steel members must be connected in the field by iron workers with bolts and/or welding.

Thus, stringent testing is also required for a steel structure. Some of the tests that would have to be considered when erecting steel are the following:
1. Proper bolts are being utilized.
2. Required tightening (torque) of the bolts needs to be accomplished by code standards.
3. Steel sections as indicated on the approved shop drawings are in fact being installed.
4. Welds have to be checked for proper thickness and continuity.
5. All welders have to be certified.
6. Shear stud connectors have to be attached to the steel with proper spacing and welds.
7. The steel has to be fireproofed with approved material that will have proper thickness, adhesion, and density.
8. All columns are perfectly aligned (plumbed).
9. Correct steel is being used (i.e., A36).
10. Proper steel camber has been placed on the steel as specified by the consultants.
11. Splice plates must be of the approved thickness.
12. Inspection at the fabricator’s shop would be helpful for checking beam camber and obtaining coupons.