BUILDING PERFORMANCE: HURRICANE INIKI IN HAWAII
Observations, Recommendations, and Technical Guidance
Learning from failure, building on success
Teaming to Reduce Future Damages
Federal Emergency Management Agency
Federal Insurance Administration
In Cooperation with the State of Hawaii Office of Civil Defense and Kauai County
FIA-23, 3/93

3.0 OBSERVATIONS OF WIND DAMAGE AND SUCCESSFUL BUILDING PERFORMANCE UNDER WIND 
LOADING CONDITIONS 

3.1 FIELD SITES 

The team surveyed the island in a comprehensive manner for wind damage. Field 
sites included the following: 

- Princeville, for examples of contemporary (post.-1974) single-family and 
multi-unit, heavy- and light-timber, one- and two-story wood-frame construction 
in exposed areas subject to amplified wind speeds and not subject to flood 
damage. 

- Hanalei, for examples of both contemporary and older, traditional Hawaiian 
construction, which coincidently is located in a flood hazard area but suffered 
no flooding of significance. 

- Anahola, Wailua, Kapaa, and Lihue, for examples of a mixture of contemporary, 
light wood-frame construction, traditional homes, and commercial establishments. 

- Nawiliwili Harbor and other sites, for examples of commercial/industrial 
metal-frame warehouse construction. 

- Kekaha and Hanapepe and vicinity, for examples of both older construction and 
a new subdivision containing light wood-frame construction. 

3.2 OBSERVATIONS OF BUILDING PERFORMANCE UNDER WIND LOADING 

Observations of the impact of wind forces included various building types 
damaged at the above sites, as well as buildings that incurred little or no 
damage. The discussion of observations presented in the following subsections 
addresses the following: 

- Modes of failure and examples of inappropriately designed and constructed 
structural systems. 

- Modes of successful performance and examples of properly designed and 
constructed structural and roofmg systems, as well as noteworthy architectural 
detailing and construction craftsmanship. 

- Roof sheathing (e.g., plywood) and roof cladding (e.g., shingles) and their 
methods of attachment. 

- Architectural features, such as the amount, type, installation, and protection 
of glazing (windows and glass doors), and roofing 
configurations, such as large overhanging, steep, or offset roof lines. 

- Windbome debris and its role in causing damage. .Quality of construction and 
workmanship. 

- Deterioration (e.g., rotting, rusting) and its role in contributing to damage. 

3.3 DIAGNOSTIC MODES OF STRUCTURAL FAILURE 

The most pervasive type of failure to primary structural systems was caused by 
uplift forces on roof systems that were incompletely or inadequately connected 
to walls. 

Primary structural systems are those that frame the building to resist applied 
forces. In residential applications, these systems are made up almost entirely 
of the exterior and interior loadbearing and non-loadbearing walls, the roof and 
floor systems, and the foundation. The integrity of the overall structure 
depends not only on the strength and deflection performance of these components, 
but also on adequate designs of the connections between the components. 

In the majority of cases on Kauai, when properly engineered and constructed 
residential units were built to define the continuous load transfer path, their 
performance under the storm conditions was significantly improved. Where there 
was construction that evidenced a breakdown in the load transfer path, damage 
extent ranged from considerable to total, depending on the configuration, type 
of construction involved, and the exposure to both flood and wind loads. 

One- and two-story wood light-frame buildings were the most severely damaged 
type of construction. Building failure was primarily a result of 1) wind 
overload to roof systems caused by uplift forces, and 2) wall failure from 
direct wind pressure on interior and exterior walls which lost top support once 
all or part of the roof was lost. Simply stated, the roof system is a key 
component that provides stability by supporting the tops of exterior and 
interior loadbearing walls and exterior non-loadbearing walls of the building. 
Geometric stability of the wall system is generally dependent on the roof as a 
top lateral support. Buildings whose walls did not fail even after the loss of 
the roof may have been geometrically stabilized by the interior partition walls, 
such as in the smaller residences with numerous interior walls. Once the roof is 
partially or fully lost, the ability of the walls to withstand wind pressure is 
greatly diminished (FIGURE 21). 

[Begin figure]
FIGURE 21. Once the roof system is compromised, the ability of the wood- frame 
exterior walls to withstand external wind pressure is greatly diminished. 
[End figure]

The roof framing systems observed were typically composed of prefabricated 
trusses or job-site-assembled timber rafters or trusses. Four key failure points 
in the loss of these roof systems were consistently observed: 

- Inadequate design. 
.Reliance on simplistic and inadequate nailing procedures to construct the roof 
structures (FIGURES 22, 23, and 24). 

[Begin figures]
FIGURE 22. Roof rafter construction with simple nailing or toenailing failed 
under uplift forces. Note two nails used to connect each rafter to hip beam. 

FIGURE 23. Toenailing of ridge beam to gable-end support. Rooffailure from 
uplift. 

FIGURE 24. Toenailing of rafter to ridge beam. Rooffailurefrom uplift. 
[End figures]

- Reliance on simplistic nailing procedures to connect the roof structure to the 
wall system (FIGURE 25). 

[Begin figure]
FIGURE 25. Toenailing of roof rafters to wall system. At this critical 
connection, toenailing does not provide the load transfer path necessary to 
withstand uplift forces. 
[End figure]

- Improperly sized, designed, or connected metal straps, fasteners, or hangers 
used to construct roof systems and/or connect roof and wall systems (FIGURE 26). 

[Begin figure]
FIGURE 26. Example of improperly sized and placed metal fastener, which led to 
roof failure from wind uplift forces. 
[End figure]

The simplistic nailing procedures (generally toenailing) used to construct roof 
systems such as rafter tie-ins to the ridge beam or rafter attachments at stud 
wall sides or comers were not adequate to withstand significant wind loading. 
This is especially true in exposed areas along coastlines or other areas 
subjected to terrain-amplification of wind speed and subsequent forces. Simple 
toenailing of rafters and wood trusses to stud walls was a regularly observed 
failure point. Such toenailing did not provide the complete load path to 
distribute the uplift and lateral loads from the roof to the walls and therefore 
should be eliminated as an accepted practice. 

Shortcomings in design and construction practices such as toenailing were 
technically allowed due to reliance on implicit provisions in the 1985 UBC. 
Appendix Section 2518 of the 1991 UBC is very explicit in its requirements and 
contains graphical presentations not contained in older versions of the Code. 
For new and repair construction, much of the structural damage observed due to 
wind forces can be prevented if provisions in Appendix Section 2518 are 
correctly implemented. 

Metal straps, anchors, or mechanical fasteners used on buildings that suffered 
roof and other structural damage were typically not sized, designed, or attached 
properly or lacked the proper coating (hot-dipped galvanizing) necessary for 
highly corrosive marine environments. Corrosion results in a loss of section and 
a loss of material strength, and the clips, anchors, and fasteners fail at loads 
below the design load. The use of metal connectors or hurricane clips in and of 
itself does not necessarily result in successful building performance. 

In one noteworthy failure that characterizes this problem, light-gage metal 
straps were nailed to the top of a vertical post, bent upward in an L-shape, and 
nailed to one side of a horizontal roof beam (FIGURE 27). Instead, a heavy-gage 
metal strap used continuously in an over-the-top or collar fashion and securely 
nailed on either side of the vertical post would have been the proper connection 
and would have provided an acceptable complete load path between the roof and 
the wall system. Graphic examples of proper load path connectors such as this 
are contained in Appendix Section 2518 of the 1991 UBC. 

[Begin figure]
FIGURE 27. Undersized and improperly attached metal fasteners led to roof damage 
from uplift forces. 
[End figure]

A second type of roof system observed was prefabricated (factory-made) light- 
wood trusses with plywood sheathing. Trusses themselves performed relatively 
well under wind loads (FIGURE 28). However, because connected trusses and 
sheathing formed the horizontal diaphragm of the building system, truss systems 
tended to become unstable and failed to varying degrees when the sheathing was 
lost (FIGURE 29). This amplified failures due to the inadequate load transfer 
mechanism between truss and wall systems, as previously described (FIGURE 30). 

[Begin figures]
FIGURE 28. Individual prefabricated wood roof trusses performed relatively well. 
BUILDING PERFORMANCE ASSESSMENT TEAM REPORT 39 

FIGURE 29. Gable-end roof failure due to loss of roof sheathing and lack of 
gable bracing. 

FIGURE 30. Improper connection (toenailing) between roof trusses and wall 
systems. When roof sheathing was blown off by wind, unbridged trusses failed, as 
did the exterior wall. 
[End figures]

Gabled roof structures were invariably more failure-prone (FIGURE 31). Hip roofs 
(FIGURE 32) generally performed better than gabled-end roofs, clearstory roofs 
(offset roof peak), and other steeply pitched roof systems. The geometric 
discontinuity in these roof lines made the roofs susceptible to high localized 
wind-induced external pressure on eaves and soffits (FIGURE 33). 

FIGURE 31. Gable-end roof designs tended to be more failure-prone. 
BUILDING PERFORMANCE ASSESSMENT TEAM REPORT 41 

FIGURE 32. Low-pitched hip roofs are aerodynamically superior and generally 
performed better than steeply pitched gable-end roofs. 

FIGURE 33. Offset roof peak provides geometric discontinuity and results in 
greater localized wind-induced pressure, which can lead to roof and then wall 
failure. 
[End figures]

Roof overhangs or soffits 3.0 feet long or less, with adequate venting, suffered 
comparatively less damage from wind forces. Overhangs exceeding 3.0 feet in many 
instances failed to resist the uplift forces and were the source of progressive 
roof structure failure (FIGURE 34). Much of this failure was due to inadequate 
installation, lack of proper engineered enclosure of extended soffits, lack of 
tie-back from rafters to wall, and improper sheathing and venting. 

[Begin figure]
FIGURE 34. Excessive roof overhang and poor connections in many instances led to 
roof failure. 
[End figure]

In summary, incomplete design for load transfer (either improper roof 
construction or improper connection between the roof and wall systems) was found 
to be the most pervasive cause of structural failure of buildings due to wind 
loads. 

3.4 DIAGNOSTIC MODES OF SUCCESSFUL STRUCTURAL PERFORMANCE 

Noteworthy examples of properly engineered and constructed buildings were 
observed in Kauai County, both tract development houses and individual custom- 
built houses. Almost without exception, successful performance resulted from 
adequately designed and clearly defined continuous load transfer paths. Where 
connections, such as hurricane clips and metal straps, were correctly applied, 
buildings performed relatively well (FIGURE 35). 

[Begin figure]
FIGURE 35. Example of very successful heavy-gauge metal fastener connecting roof 
and wall systems. Note the over the top application and the number and size of 
lag bolts used for attachment. 
[End figure]

Examples of proper building design and construction were noted in two new 
subdivision developments in Kauai County. Both contained modestly sized, single-
story, light wood-frame construction. 

The following key design and construction factors led, at least in part, to 
successful performance of homes at these sites: 

- Creation of a continuous load transfer path through the use of proper 
connections between the roof and the wall, and between the walls and the 
foundation (FIGURE 36). 

[Begin figure]
FIGURE 36. Wood splice or strap provides a secure connection between wall and 
roof systems. Bolted metal anchor provides secure connection between vertical 
member and foundation. This is a fine example of a continuous load path. 
[End figure]

- Use of roof designs that are more aerodynamically stable. Both 
subdivisions were characterized by hip roofs with low angles and modest 
overhangs. 

- Proper attachment of roof cladding to roof sheathing. Properly nailed common 
fiberglass composition shingles were used and performed adequately. 

- Attention to construction details and sensible workmanship. Examples included 
the use of simple procedures to reduce susceptibility to termite damage (FIGURE 
37), diagonal bridging between the vertical supporting members near the 
foundation and the lowest horizontal structural member of the floor system, and 
roof ventilation, which apparently relieved internal pressures. 

[Begin figure]
FIGURE 37. Sensitive craftsmanship and attention to detail: Vertical 
preservative-treated posts 1/4 inch off ground to reduce probability of termite 
infestation and decay. 
[End figure]

These examples of properly designed load transfer paths and successful building 
performance in Kauai County during Hurricane lniki provide a valuable tool for 
education and training on proper design and construction methods. 

3.5 ROOF SHEATHING 

LOSS of roof sheathing (e.g., plywood) was a consistently observed failure mode. 
The primary cause of sheathing loss was the lack of adequate nailing of the 
sheathing to the structural underpinnings of the roof system (e.g., rafters, 
trusses, and purlins) (FIGURES 38-40). Frequently observed evidence of 
inadequate attachment including excessive space between staples or nails; lack 
of staples or nails where sheathing rested on rafters, trusses, or purlins; and 
failure of staples or nails to strike rafters, trusses, or purlins. In addition, 
excessive corrosion of inadequately protected nails and staples was observed. 
Where inadequate nailing or excessive corrosion occurred, high winds were often 
able to peel the sheathing from the roof structure. 

[Begin figures]
FIGURE 38. Improper attachment of sheathing to purlins. Note wide spacing, 
shallow penetration, misalignment, and corrosion of staples. 
BUILDING PERFORMANCE ASSESSMENT TEAM REPORT 47 

FIGURE 39. Improper nailing design and schedule for purlin-to-rafter attachment. 
Note infrequency of nails for large surface area. Nowhere is the plywood 
sheathing directly nailed to the rafter system. 

FIGURE 40. Loss of roof sheathing due to improper nailing design and schedule. 
48 BUILDING PERFORMANCE ASSESSMENT TEAM REPORT 
[End figures]

Once sheathing was lost, damage was increased by rainwater. Stripped sheathing 
was also a source of airborne projectiles which caused additional damage to 
adjacent buildings. Sheathing loss was particularly troublesome because 
sheathing composed a significant part of the building envelope. Sheathing loss 
often led to progressive roof structure failure. This in turn led to a loss of 
support for the tops of both interior and exterior walls. In many cases, this 
led to major structural damage and even total loss. 

Loss of sheathing was especially critical where roof structures (rafter or truss 
systems) were engineered. In these instances, the roof structure relied on the 
plywood to provide rigidity to the roof diaphragm. Once the sheathing was peeled 
from the purlins or trusses, the roof structure became unstable and highly 
susceptible to damage (FIGURE 41). 

[Begin figure]
FIGURE 41. Total roof failure due to loss of sheathing. 
[End figures]

Adequate roof rafter connections and use of truss bridging, proper roof system- 
wide lateral bracing, adequate cross-bracing at gable end trusses, and 
stiffening of the gable ends were observed to have provided additional 
structural roof support and supplemented the sheathing diaphragm for structural 
support. 

Corrugated metal roofing is the predominant type of roof covering in Kauai 
County. In most cases it is used on small 800- to 1200-square-foot rectangular 
wood-frame "single wall" structures that typify the traditional architecture 
style in Hawaii. Failure of this roofing material occurred at points of 
attachment to underlying rafter systems (FIGURE 42). Such damage was attributed 
to improper fastening procedures and, in some instances, to rusting of metal 
panels at nailing locations, or to significant corrosion of the nails. 

[Begin figure]
FIGURE 42. Failure of corrugated metal roof at attachment points. These small, 
geometrically stable, "single wall," rectangular structures with numerous 
interior partition walls often remained structurally intact after loss of metal 
coverings. 
[End figures]

Usually, however, loss of corrugated metal roofs did not lead to further 
structural failure of buildings because 1) the metal sheets were simply 
coverings and do not serve to act as a stiffening for the roof diaphragm to 
provide structural stability to the walls and 2) the buildings on which these 
roofs are usually found are inherently stable as a result of their small plan 
size, rectangular shape, and numerous interior partition walls. Thus, loss of 
corrugated metal roofs, with the exception allowing some internal wind pressure, 
did not significantly decrease the structural integrity of these traditional-
style buildings. 

Loss of corrugated metal roofing was nonetheless a significant problem because 
of the resulting rainwater damage and the generation of windbome projectiles 
(FIGURE 43). Thus, considerable effort should be given to teaching building 
contractors, and especially homeowners, the proper fastening of corrugated metal 
roofing to the underlying rafters and purlins. 

[Begin figure]
FIGURE 43. Metal roof loss generates large airborne projectiles, which often 
cause additional damage. 
[End figure]

3.6 ROOF CLADDING 

Damage to roof covering or cladding such as extruded concrete and clay tiles, 
wood shakes, fiberglass composition shingles, and underlayment material was 
extensive at most field sites. While many structures escaped very costly 
structural frame damage, most structures suffered some degree of roofing damage. 
Damage to roof cladding permitted further damage to building interiors from 
high-velocity winds and rain, particularly since the common practice is to 
support concrete tile and wood shake roofing on spaced wood strips rather than 
complete roof sheathing. 

Close observation revealed that attachment procedures (stapling or nailing) for 
cladding types were deficient at many locations (FIGURE 44). Rarely was material 
failure caused solely by wind pressure. It was observed that less damage 
occurred to roofs where either staples or nails were sized and installed to 
generally accepted standards of construction practice. In some instances, 
individual tiles were observed that had not been nailed (FIGURE 45). 

[Begin figures]
FIGURE 44. Loss of roof cladding due to failure at attachment points. Notice 
that many staple crowns have corroded away on staples used to attach wood shake 
roofing to plywood roof sheathing. 

FIGURE 45. Heavy concrete tile attached at one point with undersized nail. It 
was also observed that neighboring tiles had not been nailed. 
[End figures]

Examples of properly attached roof cladding (both composition shingles and 
extruded tiles) with little or no damage were noted. Also notable was the better 
performance of cladding on flatter roofs. 

In general, there were failures observed of each of the attachment components 
that were integral to the proper installation of precast and molded tiles, 
either extruded concrete or clay. Underlayment failure, lack of attachment of 
each tile, and lack of mortar pads on ridge and steep-sloped sides were all 
observed. The use of mortar pads to provide improved adherence of roof tiles is 
not generally practiced in Kauai County. However, mortar has been shown to 
significantly improve adherence of the roof tiles. 

Roof cladding materials (tiles, shakes, or shingles) are designed to work 
together to form a secure attachment to underlayment and function as a 
continuous skin. Loss of one piece allows wind to effectively penetrate under 
and lift the next piece. This explains I the chain-reaction failure mode of 
shakes and tiles once debris impact or improper attachment allowed wind to 
remove the first few pieces of cladding (FIGURE 46). 

[Begin figure]
FIGURE 46. Roof cladding system composed of interdependent elements. Failure of 
one tile led to failure of adjacent tiles in a "chain reaction" effect. 
[End figure]

3.7 GLAZING AND TRANSPARENT OPENINGS 

Openings in exterior walls and roofs receive the various door, window, and 
venting systems necessary to complete, fully functioning architecture. The 
observed failures of the door and window "inserts" were typical of those that 
occur during high-wind events. These failures resulted in a breach of the 
building's envelope and allowed wind to directly enter the interior of the 
building. This resulted in an uncontrolled buildup of internal pressure that 
overloaded the building's structural components. While most glazing should be 
protected prior to significant storms, all other opening components should have 
performed acceptably without additional reinforcing. 

Failure of glazing (glasswork), such as windows, sliding track doors, and hinged 
doors, contributed to a significant percentage of the damage to buildings. 
Moreover, once glazing components and doors failed (FIGURE 47), the structural 
integrity of the building was compromised as previously described. Given an 
entrance path for uncontrolled wind forces, the interior components then become 
subject to wind and rainwater damage. More importantly, these openings, coupled 
with the penetration of wind, make buildings much more susceptible to extensive 
structural damage due to rapid buildup of internal wind pressures (FIGURE 48). 
The larger the area that is compromised, the greater the potential for damage. 
This process was a primary mode of failure of buildings in many areas, 
especially Princeville. 

Failure of exterior wall openings occurred in two ways: 1) shattering of glazing 
from projectile impact (FIGURE 47) and 2) implosion or explosion of glazing due 
to the combination of wind pressure and improper installation (FIGURE 49). 

[Begin figures]
FIGURE 47. Glazing broken by windborne debris or direct wind pressure. 

FIGURE 48. Loss of opening protection allows wind entry and increases internal 
exposure. 

FIGURE 49. Implosion of transparent shatter-resistant sliding door. Failure of 
door frame due to improper attachment to structural elements. 
[End figures]

Improper installation, for example, inappropriate attachment of window frames to 
the structural elements of the wall (FIGURE 50), and weak connections of 
expansive sliding doors (FIGURE 51), were consistently observed causes of the 
failure of glazing units. Where shatter-resistant material was used, failure was 
frequently observed where the material remained intact, but the unit, as a 
whole, was displaced inward by wind pressure (FIGURE 52) due to bowing and 
subsequent failure at the perimeter connections. 

[Begin figures]
FIGURE 50. Improper attachment of window unit. Note only one connection 
(nailing) point between unit and wall structure at the single shim. 

FIGURE 51. Improper connection of sliding glass door. Track attached with only 
three screws in vertical member. Sliding track on floor attached with caulk 
only. 

FIGURE 52. Gable-end window unit as a whole was displaced inward by wind 
pressure. Apparently, this allowed wind entry, increased interior pressure, and 
caused roof uplift. 
[End figures]

Open exposure of frangible (glass) windows and doors during high winds is 
problematic. Obviously, transparent components, including glazing, are 
fundamental and necessary architectural features of all residential structures. 
Yet, the use of glasswork over large, exposed surface areas without adequate 
protection significantly increases the potential for internal damage, and even 
seriously jeopardizes the performance of structures exposed to high wind loads 
and flying debris (FIGURE 53). Without the use of in-place working shutter 
systems (FIGURE 54), emergency protection such as securely fastened plywood, or 
non-frangible transparent materials, survival of glass work from flying debris 
becomes random chance. 

[Begin figures]
FIGURE 53. Extensive use of glazing on windward side can significantly 
compromise a building's envelope and lead to roof failure. 

FIGURE 54. In-place protective devices for glazing reduced the occurrence of 
building envelope failures. 
[End figures]

Furthermore, glasswork should be properly designed according to the same 
criteria used for the structure itself. Properly designed glasswork provides a 
factor of safety from failure due to direct wind pressures. 

3.8 WINDBORNE DEBRIS 

The primary sources of windborne debris, probably in decreasing order of 
prevalence, were improperly installed roof cladding (e.g., shingles, tiles, and 
shakes), structural failure of roof systems and thus wall systems, and 
improperly installed roof sheathing (e.g., plywood). Although windborne debris 
caused some damage to exterior siding from direct impact (FIGURE 55), by far its 
primary effect was in the shattering of unprotected glazing such as windows and 
glass doors. 

[Begin figure]
FIGURE 55. Windborne debris impact can puncture building and allow buildup of 
internal wind pressure. 
[End figure]

Thus in hurricanes such as Iniki, the modes of building failure are 
interconnected: Loss of roofing due to improper structural attachment or 
improper installation contributed to the number of windborne projectiles; this 
in turn significantly increased the potential for compromise of windows and 
doors and failure of neighboring buildings; this in turn further increased the 
number of windborne projectiles. 

As discussed in Section 4.0, the team observed that properly engineered and 
constructed architectural and structural components, attention to detail in 
attachment of roof cladding and sheathing, and proper design and protection of 
glazing components significantly reduced damages caused by windborne 
projectiles. 

3.9 DETERIORATION 

Weakening of structural components, sheathing, and cladding was caused by insect 
(termite) infestation and weatherization (rotting and rusting). This reduction 
in strength acted to increase damage. Several procedures could have been used to 
mitigate hurricane damage due to previously weakened wood and metal building 
material: 

- Use of proper building material, such as chemical-pressure-treated lumber, to 
reduce insect infestation, or corrosion-resistant fasteners to reduce attachment 
failures due to weakened fasteners. 

- Use of pre-painted wood and metal and periodic maintenance to reduce open- 
weather deterioration. 

- Application of sensible construction practices that reduce the probability of 
deterioration. For example, taking care that no part of a wood foundation system 
comes into contact with the soil (FIGURE 37). 

- Inspection and replacement of damaged elements. 

3.10 PRE-ENGINEERED STEEL WAREHOUSES 

Several pre-engineered steel warehouses at Nawiliwili Harbor, as well as other 
structured steel structures were analyzed. Warehouse failure typically included 
loss of light-gage metal sheet cladding (FIGURE 56) and, in several cases, 
failure of main structural members (FIGURE 57). Obvious points of failure 
included sill-to-concrete- foundation attachments (FIGURES 58 and 59) and 
rusting at attachment points. 

{Begin figures]
FIGURE 56. Steel warehouse failure commonly was due to loss of light- gauge 
metal sheet cladding. 

FIGURE 57. Steel warehouse failure was also due to failure of structural steel 
members. 

FIGURE 58. Failure of steel warehouse due to age and weatherization and 
insufficient anchorage to resist uplift. 

FIGURE 59. Steel warehouse, sill-to-concrete-foundation failure at anchoring 
points. 
{End figures]

Because these structures are generally pre-engineered by manufacturers, and 
referred to in performance language in the UBC, a detailed discussion of design 
considerations and failure modes is beyond the scope of this report. For further 
details refer to a report currently being prepared by the Structural Engineers 
Association of Hawaii.