I’m going\u00a0to tell you about defects\u00a0in a building designed by architects and engineers.\u00a0 Defects that should not have occurred and might have resulted in civil litigation in another time and place.<\/p>\n
I don’t know whether to feel delighted or embarrassed on finding\u00a0defects in an addition to a building constructed while I was at the University of New Brunswick (UNB).\u00a0 I was in the building last fall for\u00a0a reunion of my engineering class.<\/p>\n
I\u00a0pick delighted<\/em> because I know that failures occur and finding them reminds us we can’t be too diligent and thorough in our work.\u00a0 Even well educated, trained and experienced planners, architects, engineers and builders.\u00a0 We got to be ever-vigilant that we don’t drop the ball in the face of tight budgets and schedules.<\/p>\n Failure occurs when a component of a building or civil engineering structure doesn’t function as it should, has a defect,\u00a0or collapses completely.<\/p>\n 1st Defect<\/span><\/p>\n I noticed the first defect years ago when I was studying at UNB.\u00a0 Construction of\u00a0an addition undermined the foundations of\u00a0an existing building causing the foundations to settle and the brick wall in\u00a0a classroom to crack. (see Appendix) You could see daylight through the 1″ crack (it’s been caulked since).<\/p>\n Cause of 1st defect<\/span><\/p>\n The undermining causing the crack was due to the technique used during construction of the foundations to the addition.\u00a0 The technique is well known, including it’s limitations that must be taken into account.\u00a0(see Appendix)\u00a0If not, foundations are undermined and cracks appear in brick walls.\u00a0 Or worse. (see pictures of a catastrophic failure in Ref. 1)<\/p>\n 2nd Defect<\/span><\/p>\n I noticed last fall that the floor level of the addition was several inches different from the floor of\u00a0the older part of the\u00a0building.\u00a0 Such a difference in floor level contravenes some guidelines and could be construed as unsafe.\u00a0 This is the second defect in this building of which\u00a0I’m aware.<\/p>\n Cause of 2nd defect<\/span><\/p>\n The cause of the mismatched floors is certain to have occurred during planning and design of the room height in the addition – an initial hypothesis.\u00a0 The\u00a0floor to ceiling height\u00a0in the existing building was not measured so planning and design could ensure\u00a0the floor of the addition matched the floor of the existing.\u00a0 Or\u00a0it was measured but the information not used.<\/p>\n The difference in floor\u00a0level would not be due to foundation settlement nor to building shrinkage.\u00a0 The difference of several inches is just too great.<\/p>\n Two defects in the planning, design and construction of an\u00a0addition to a building?\u00a0 Overseered by planners, architects and engineers?\u00a0 I’m certain someone was embarrassed\u00a0back then.<\/p>\n No excuse for defects<\/span><\/p>\n Two defects in a building – one in the planning and design stage and a second in the construction stage – that should not have occurred.\u00a0 These\u00a0potential problems\u00a0are too well known to experienced planners, architects, engineers and builders\u00a0and could have been avoided.<\/p>\n References<\/strong><\/p>\n ***<\/p>\n Appendix <\/strong><\/p>\n My first “forensic engineering” investigation. <\/span><\/strong><\/p>\n The following is one in a series of cases I\u00a0have\u00a0investigated\u00a0that illustrate\u00a0the different types of failures<\/strong> and accidents<\/strong> that occur resulting in civil litigation<\/strong>, and the forensic engineering methods I used to investigate the cause.\u00a0 I investigated this failure when I was studying civil engineering\u00a0at UNB\u00a0and\u00a0hardly knew what a forensic investigation was.<\/em><\/p>\n The investigation is reported under the following headings with several sub-heads:<\/p>\n I carried out my first “forensic engineering”\u00a0investigation\u00a0during my 5th year studying civil engineering at\u00a0UNB.\u00a0\u00a0As a student I\u00a0had little or no understanding of forensic engineering and wasn’t even qualified as a professional engineer.<\/p>\n Nevertheless, this was a significant and costly building failure but, fortunately, not a catastropic one. (see pictures of a catastrophic failure in Ref. 1 above)<\/p>\n We took some of our lectures in a room on the second floor of a two story brick-walled building on the campus.<\/p>\n One day a\u00a01″ wide, vertical\u00a0crack appeared in the front, left corner of a wall of the lecture room.\u00a0 (I measured the caulked crack last fall during our reunion)\u00a0 You could see daylight through the crack.\u00a0 This would be significant damage to an existing building<\/p>\n “Legal”\/Technical\u00a0issue<\/span><\/p>\n To me as a student with an interest in\u00a0geotechnical and foundation engineering, the cause of the crack was interesting.\u00a0 I investigated and reported on the cause\u00a0to meet the\u00a0requirements of one of\u00a0my courses.<\/p>\n “Client”<\/span><\/p>\n My “client” was the professor who was giving the foundation engineering course at UNB.<\/p>\n My\u00a0“forensic engineering” investigation involved the following:<\/p>\n Visual examination<\/span><\/p>\n A visual\u00a0examination of the exterior of the building found that an addition to the building was being\u00a0constructed\u00a0adjoining the existing building.\u00a0 Construction\u00a0involved a deep excavation adjacent the\u00a0existing building.\u00a0 The sides of the excavation were\u00a0supported by steel beams and timber planks.<\/p>\n Construction of the building’s<\/em> foundations<\/span><\/p>\n I\u00a0learned that the existing building was supported on shallow spread footings founded in the natural soils.\u00a0 Excavating near and well below\u00a0natural foundation soils requires their lateral support to prevent undermining the soils.\u00a0 The soils could cave into the excavation –\u00a0collapse catastrophically –\u00a0unless properly supported.<\/p>\n Construction of the addition<\/em> to the engineering building<\/span><\/p>\n I\u00a0learned during my visual examination that the pile and plank, excavation support system installed by the contractor was a\u00a0soldier pile<\/em> shoring system.\u00a0 This system is intended\u00a0to temporarily support the sides of the excavation and in this way the foundation soils\u00a0beneath the\u00a0existing building.<\/p>\n Soldier piles are steel beams installed vertically in the ground at regular intervals of several feet at the side of where an excavation is planned adjacent existing foundations.\u00a0 The piles are set deeper than the planned depth of the excavation.\u00a0 The piles are driven vertically in the ground, or installed in previously bored holes eliminating the ground vibration from\u00a0pile driving.<\/p>\n As the ground is excavated on one side of the piles, wood planks are placed horizontally bridging between the piles to hold the earth back on the other side – to shore up the side of the excavation from caving in.\u00a0 In this case, the earth at the back is adjacent the earth comprising the foundation soils of the existing building.\u00a0 The planking or lagging “follows” the excavation down.\u00a0 This is a soldier pile shoring system.<\/p>\n A soldier pile shoring system is a good support system if constructed properly and its limitations kept in mind.<\/p>\n Research construction technique<\/span><\/p>\n I researched the soldier pile shoring system and found that it “gives” or yields a little – deflects along it’s\u00a0height\u00a0– when mobilizing its strength to provide support to the soil it is retaining.\u00a0 The retained soil\u00a0behind the shoring system gives a little as well\u00a0–\u00a0moves sideways and away from the foundation soils to which it is providing lateral support.\u00a0 This undermines the foundation soils a little causing the soils\u00a0to settle and the building foundations to settle as well.<\/p>\n This deflection\u00a0is due to the piles bending along their length.\u00a0 The piles will also tilt a little if they are not\u00a0driven or embedded deep enough during installation.<\/p>\n This lateral movement of the shoring system and settlement of the soils and foundations is normal.\u00a0 It\u00a0can be\u00a0negligible – tiny millimetres or less – if the shoring system is properly designed and installed.\u00a0 The movement can be significant –\u00a0 centimetres, inches or more – causing damage to the foundations, if\u00a0the support system\u00a0is not well designed and installed.<\/p>\n Installing soldier piles by driving them in place causes the soils in the immediate area to vibrate.\u00a0 Soil settles when it is vibrated.\u00a0 Anything in the soil – like building foundations –\u00a0settles as well.<\/p>\n I analysed the data that I had collected – construction of the\u00a0shoring system and the results of my research –\u00a0and\u00a0concluded\u00a0the cause of the failure and submitted my student engineering report.<\/p>\n In this case the soldier pile\u00a0system deflected too much causing the foundation soils to yield or move\u00a0sideways and settle in the process.\u00a0 This caused the building walls to settle as\u00a0well and the corners to crack and open up.\u00a0 The soldier pile deflection was probably due to a combination of the following causes noted above:<\/p>\n I passed my year so I must\u00a0have got it right.\u00a0 I understand that some of the engineers who\u00a0inspected\u00a0the soldier pile system that failed may have been\u00a0my professors who had formed\u00a0a consulting engineering company to do this type of engineering design and inspection work.\u00a0 Failures occur in spite of the best efforts\u00a0of the best people.<\/p>\n <\/p>\n <\/p>\n","protected":false},"excerpt":{"rendered":" I’m going\u00a0to tell you about defects\u00a0in a building designed by architects and engineers.\u00a0 Defects that should not have occurred and might have resulted in civil litigation in another time and place. I don’t know whether to feel delighted or embarrassed … Continue reading \n
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The case<\/strong><\/h1>\n
“Forensic engineering”\u00a0investigation<\/h1>\n
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Cause<\/h1>\n
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Post mortem<\/strong><\/h1>\n