ENVS 10003 CONSTRUCTION LOG BOOK
Week 10: When Things Go Wrong eLearnings • Elasticity and Stress • Lateral Loads • Strategies to Resist lateral loads • Environmental Awareness and Economic Efficiency of Materials • Unsuitable Materials
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ENVS 10003 CONSTRUCTION LOG BOOK eLearnings When things Go Wrong Elasticity and Stress -Each material has distinct properties of strength, elasticity and stiffness, The most effective materials are those that combine elasticity with stiffness -Elasticity-the ability to deform under stress-bend, stretch or compress-and return to its original shape with the applied stress removed. -Every material has an elasticity threshold-beyond this limit it will break or permanently deform. -Materials that undergo deformation before actually breaking are termed ductile -Stiffness is a meaner of the force required to push or pull a material to its elastic limit. -A materials stiffness, along with its cross sectional stiffness are important factors when considering the relationship between span and deflection under loads Practical Considerations -The dimensional stability of a material as it responds to changes in temperature and moisture content affects the manner in which it is detailed and constructed to join with other materials -The thermal conductivity or resistance of a material determines its resistance to wear and abrasion, its durability in use, and the cost required to maintain it -The ability of a material to resist combustion or withstand exposure to fire, and not produce smoke or toxic gasses, must be evaluated before using it as a structural member or an interior finish
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ENVS 10003 CONSTRUCTION LOG BOOK Lateral Forces Wind and earthquake forces have different effects or structures: Wind Force is a function of the size of the exposed surface area to the amount of wind action -Minimum active value at the base -Maximum active value at the top -Effects cantilevered structures for severely as they have reduced vertical support Earthquakes Force is a function of the amount of mass above a foundation system -Forces become exaggerated when the structure is tall and narrow -Seismic forces act at the base and can abruptly reverse direction during quake
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ENVS 10003 CONSTRUCTION LOG BOOK Strategies to Resist Lateral Forces Structural Bracing and Sheers Diaphragms -Bracing of the structure and diaphragms/sheer walls-transmits loads to cross braced walls
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ENVS 10003 CONSTRUCTION LOG BOOK Structural Separations -Can be used for irregular construction; where one end may be effected more than the other when a lateral load is applied
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ENVS 10003 CONSTRUCTION LOG BOOK Moment Resisting Frames -Where the horizontal and the vertical reinforcing of a structure act together to resist lateral loads
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ENVS 10003 CONSTRUCTION LOG BOOK SBI -Seismic Base Isolator-separates the structure from the ground through a series of foundation plates composed of a lead core and rubber and steel plates
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ENVS 10003 CONSTRUCTION LOG BOOK Specific Selection of Materials with Environmental Awareness and Economic Efficiency Environmental Considerations: The Material Life Cycle • Extraction process -Renewable or nonrenewable? • Processing of raw materials manufacturing -How much energy and water is required? • Packaging -How much energy and water is required? -Is it over packaged? • Transportation -Proximity to destination -Availability locally or shipped from a distance? • Usage -Does the material perform as intended function efficiently and effectively? • Maintenance -How durable is the material or product and does it require frequent maintenance? -How does the material affect the indoor air quality • Recycling/disposal -Toxic by-products? -Waterborne effluents -Atmospheric emissions -Solid wastes
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ENVS 10003 CONSTRUCTION LOG BOOK Material Selection Relies On: • Health and IEQ-Indoor Environment Quality -choose material that is healthy on an every day basis-more comfort equals more productivity -reduced VOC-volatile organic compounds -minimise dust capture capabilities -minimum cleaning process • Waste/Recycling/Recycled -renewable resources-bamboo floors rather • Energy Use and Embodied Energy -low embodied energy -low transport cost-Australian made • Pollution -minimise waste-low embodied toxins -production process may be environmental damaging -organic and natural materials • Life Cycle -economic efficiency in maintenance and recycle -design with purpose and durability
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ENVS 10003 CONSTRUCTION LOG BOOK Unsuitable Materials Case study on Beach house -Cracking north facing fascia board due to irregular heat transfer-was painted black on one side and this caused warping and deflection -Zinc-aluminum cladding glued to a plywood base was used to resist corrosion -Glue was insufficient structural material-started to blister due to extreme heat exposure -Glue not a suitable method for construction in these circumstances-caused mass delamination between plywood and corrosive resistant coating -Structure was re-clad with marine grade plywood, -Clad over the top of old material and problems arose due to condensation and chemical reaction (galvanic reaction) between the zinc aluminum cladding and plywood Summary: Material needs to be suitable for the required performance in a particular environment Material and construction technique requires constant performance over the life and duration of the structure The Statue of Liberty -Copper oxidization of exterior -Corrosion of the Iron rib structure and the copper skin -metal compatibility- dissimilar metals react and corrode-Galvanic Reaction -Similar metal resist corrosion -Iron ribs replaced with Stainless Steel and Teflon coat Note: For non-corrosive construction, metals must be similar; close to each other on the chart. The greater the distance between the metals the greater the corrosive reaction.
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ENVS 10003 CONSTRUCTION LOG BOOK References All information was sourced and adapted from •
Ching, Francis D.K., (2008)., building construction illustrated., 4th ed., New York: Wiley.
Images are referenced individually All images that are not referenced were taken by myself on site of construction
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