Opinion ID: 384591
Heading Depth: 2
Heading Rank: 2

Heading: The Causes of the Collapse of the Dome

Text: 10 Two experts testified, one for Butler and one for Dow. They were in substantial agreement as to the factual causes for the collapse of the dome. The issue before us, as will be more fully developed below, is whether these factual causes may be ascribed, within the meaning of the policy, to faulty workmanship on the part of the subcontractor Dow or its subcontractors, a covered risk; or, instead, to faulty design or to faulty testing within the meaning of exclusion clauses excepting these risks from coverage. 11 We will accept the description of the causes of the loss as set forth in the appellee Royal's brief, with two slight omissions (indicated and explained by footnotes 1 and 5): 12 On August 22, 1973, the first of the 221-foot diameter domes collapsed during construction. (C.R. 760). An investigation was conducted by an expert from Dow, Steven Waling. His report, which was introduced upon trial of this cause, indicated that four factors, in combination, caused the collapse. (C.R. 763). One factor was termed a capacity and the other three factors were termed impositions. As the capacity Mr. Waling pointed to (1) incomplete thermal fusion and corresponding reduced tensile capacity of the interface of the foam logs. (C.R. 763). Tests performed following the collapse indicated the tensile stress and tension were both consistently less than 10 psi (pounds per square inch) in the pass area where the fracture occurred. (Tr. 62). This simply means that the capacity of the welds was approximately 10 psi. The capacity of the welds should have been in the 27 psi range. (Tr. 59, 64).... ( 1 see p. 63. 13 The next factor given, and the first imposition, was (2) unsymmetrical gravity loading of freshly placed concrete. (C.R. 763). On the day in question concrete was being placed at the 60 and 70 foot level (of a 130 foot arc) in many instances in layers of three-fourths to one and one-half inches. (Tr. 65). This was obviously greater than the specification of three-eighths to one-half inch per layer. (Tr. 65, 66) (C.R. 763). The placement of concrete was also unsymmetrical, in that it was being placed on only one quadrant of the dome at that particular point in time. (Tr. 65). ( 2 14 The next factor, and the second imposition according to Mr. Waling, was (3) the restraint displacement imposed by the scaffold. ( 3 As the dome cooled down during the night the depression would come into contact with the scaffold and be restrained. (Tr. 71). The scaffold would not have been present but for the existence of the depression (dimple). (Tr. 71). 15 The final factor and third imposition was (4) thermal loading and corresponding restraint of the shell form. Dow experienced ambient temperature changes of as much as 50 degrees a day which resulted in significant expansion and contraction of the shell form. (Tr. 73). During the expansion phase the styrofoam dome would be restrained by previously placed concrete. (Tr. 73-76). ( 4 16 Taking into account the additional concrete weight located across from the point of fracture, the restraint displacement of the scaffold support, and the increased stiffness in the area filled with wire reinforced urethane foam (the depression (or dimple)), a combination of impositions yielding a tensile stress in the range of 12.7 psi would have been present. (Tr. 77). Moreover, dome expansion as a result of temperature rise and the restraint of previously placed concrete would yield a tensile stress in the range of 11.04 psi. (Tr. 123). Thus, any one or all of the impositions in combination with the reduced tensile strength capacity of the welds explains the collapse. If the thermal fusion of the foam logs had been accomplished according to expectation (in the range of 27 psi) ... ( 5 the other contributing factors would not have initiated the failure at that point in time. (Italics supplied by us.) 17