Quality Assurance 3 Key Aspects –Quality Engineering –Quality Control –Quality Assurance

Quality Assurance Quality Engineering Procedures use to ensure engineering and design proceed according to critical set by related professional and trade assoc., building codes, reg., etc. need to get drawing right expensive to correct

Quality Assurance –Quality Control Setting specific standards for const. performance usually through plans and specs. Measuring variance from std. Taking action to correct or minimize adverse var. Planning for improvements in the standards and conformance with the standards Physical work conforms to standards

Quality Assurance –Quality Assurance Application of standards and procedures to ensure product meets or exceeds standards criteria Doc of all steps to show satisfactory progress transcends both QE & QC

Elements of Quality Quality Characteristics –Dimensions, color, strength, etc –Use concrete Quality of Design –Tolerance of dimension or size –High tolerances increase cost –Need to be aware of where and what you are designing Quality of Conformance –% physical work conforms to standard Quality System

Economy of Quality Quality Economy of Design –As value increases, cost increases –As quantity increases, use of high quality/ unit decreases –Need to look at trade offs Where is the cost of quality worth it Is high quality framing necessary?

Eco of Quality Conformance Cost of skilled labor Cost of monitoring and verifying quality of work and correcting defective work need to know trade offs Is it cheaper to hire high quality craftspeople or more supervisors?

Org. for QA Owner wants –max quality of characteristics associated with function of project –without undue cost Statistical Concepts –Deal with quality characteristics which can be measured –Strength tests, spacing –Deal with qualitative observations or attributes Illumination, word inspection (can you read)

Control Charts Document central tendencies (mean, median) and measure dispersion (var.  ) –Avg and range Chart types –Avg and  –X of each of batch –  of each batch –Distribution

Sample Attributes – take some samples to represent total –take 5 from 25 –If not rep of entire 25 then trouble –producer risk vs. consumer risk Practical Considerations –Look for extraneous factors

Concrete Example For given strength can reduce cement and material costs in at least 3 ways –Larger aggregate – reduce surface area –Maintain H2O/Cement ratio while reducing H2O and cement  reduces slump –Use QC and bring mix to design spec. Want either: 1. No more than 10% fail 2. No more than 20% fail Need to design concrete for higher average strength

X = Specified strength X’ = Design strength X i = Strength of design i  = SQRT[ n  i=1 (x i – x) 2 /n] v = (  /x) * 100% t = Standard var (#  from mean) = (x – x ) /   = V x’ t = (x–x’ )/ V x’ x’ = x/(1+vt)

Safety and Health Const = 6% of labor force 12% of labor injuries 19% of labor fatalities = $5 - $10 B (early 1990s)

Motivators for Improved Health and Safety Humanitarian – reduce pain and suffering Economics – high insurance  no bids –Rates adj depending on type of work and Co history –Co can earn dividends for good records –Interrupted production, morale, –lower productivity also cost $ Legal and Regulatory Constraints –OSHA –Liability Problems –Organizational Image –Good safety records  get better workers, better productivity, loyalty

Problems  Safety Hazard –poses imminent danger of injury or death to workers or damage to mat’l and equipment –Result from poor site planning, lack of training, poor supervision, attitude  Health Problems –Need to wear ear plugs, hard hat, respirator, knee pads, back brace –Hazards include heat, radiation, noise, dust, shock vibration, toxins, disregard –Occupational Disease

Behavioral Approach to Safety and Health Policies on Safety Instruction –Job Safety Mtg – need every 10 weeks –Safety Equip. – need to increase Physical Approach –Inspection – in house reduces OSHA fines –Preplanning – make sure const. method is safe and that crew is trained

Risk Mngt need to ID and quantify potential exposures and plan to mitigate or eliminate consequences Risk ID –Internal, external, predictable, unpredictable, technical, non-technical –Some risks are owners, others are designers –Make sure risk is assigned to correct party

Construction Ins –Workman’s Comp – Avg U.S. is 18.1% of payroll –Comprehensive General Liability Negligent acts occurring in conduct of business which results in injury of physical damage 15% of payroll –Contractual Liability- protects contractor when he assumes liabilities through contract –Professional Liability arch and eng. (errors & omissions) –Builder’s Risk cost of damage to a building on project; also applies to materials and supplies on site or in transit –Equipment Floater Policy – covers const. equip.