Scott Schiff

Wind damage to envelopes of houses and consequent insurance losses

Abstract Examination of insurance claim files from Hurricanes Hugo and Andrew has revealed that most wind damage to houses is restricted to the envelope of the building. Rain entering the building then causes the insurance loss to be magnified by a factor ranging from two, at lower wind speeds, to nine at higher speeds. In wooded and urban areas near the coast, damage to buildings and their contents generally begins when the gradient wind speed reaches 40 m/s. There is a linear increase in the average insurance loss with wind speed until the gradient speed reaches about 70 m/s, at which point the average loss is approximately 12% of the insured value. Between 70 and 82 m/s (the upper limit observed in Hurricane Andrew) the average loss increases rapidly to 75%, although some small areas may experience losses over 90%. This rapid increase is associated with the loss of roof sheathing and damage to windows and doors. Probabilistic relationships are developed for expected insurance losses. These show that most hurricane-prone cities are more vulnerable to damage than inland cities, but South Florida represents an extreme risk. To reduce the vulnerability of future housing, it is recommended that envelopes be designed for the same probability of failure as the main structural system. A program to determine design loads and envelope component resistance is described. However, improvements in the wind resistance of the building stock will be slow and hurricane losses will remain high, unless large and aggressive retro-fitting programs are iniated.

Behavior of Light-Framed Wood Roof-to-Wall Connectors Using Aged Lumber and Multiple Connection Mechanisms

Ensuring a complete load path in light-framed wood structures is critical in providing proper load transfer during wind and seismic events. Roof-to-wall metal-connectors are often used to accomplish this goal. Currently, the design and construction community utilizes published metal connector capacities found in manufacturer documentation or other design aids to properly size connectors for a given demand. However, with the ever-increasing trend of using recycled dimensioned lumber and in situ retrofits of older buildings, the limited supply of research in this area is becoming more apparent. At present, the state-of-the-practice does not provide guidance to account for changes in material properties in structurally sound reclaimed or aged lumber. This study uses dimensioned lumber that was extracted from decommissioned buildings, originally built in the 1960s, to examine the effect of reclaimed dimensioned lumber on the design strength of connections by using metal-connectors. Through the use of testing ...

Special session - enhancing student learning using SCALE-UP format

SCALE-UP (Student-Centered Activities for Large Enrollment Undergraduate Programs) is a specialized active learning format that relies largely upon social interaction among students, instructor, and learning assistants. The instructor and learning assistants serve as facilitators of guided inquiry by asking students leading questions as they work through class assignments. On-going, real time formative assessments ensure that the instructor is constantly aware of which students are mastering the material and which are struggling. The SCALE-UP format is currently used at our institution in the General Engineering program (all sections of the first year courses), Math Sciences (all sections of first year calculus, and one section of second year calculus), Civil Engineering (one section of engineering statics), Mechanical Engineering (all sections of engineering statics and dynamics), as well as in courses in Horticulture, Nursing, English, and Computer Science. This special session focuses on strategies for successful implementation of this pedagogical innovation. These include development of student activities, formative assessments, training for instructors and learning assistants, and the physical features of the learning environment.

Framework for the Assessment of Building Envelope Failures Due to Hurricane Wind Hazards

This paper proposes a modular framework utilized to assess the risk of building envelope failures due to hurricane wind hazards. A component-based approach is taken to develop an integrated building envelope model that is based on previous research of individual component and system capacities. Key modules of the proposed framework include a wind-borne debris generation module and an impacttracking module that will interact with a hurricane simulation module capable of simulating synthetic hurricanes for various return periods and historical hurricanes. One major difference between the proposed framework and other risk assessment models is that the proposed framework is extremely flexible in allowing the user to define the building stock within the area of study, which will provide the user with the ability to investigate an unlimited number of “what if” scenarios. Another distinction of the proposed framework is that it is driven by a three-dimensional probabilistic debris trajectory model developed by the authors, rather than using damage curves developed from observed post-hurricane assessments or insurance claim data. Debris impact risk plots presented in a polar coordinate system are developed using the framework and can be utilized either pre- or post-construction to mitigate the damage to the building envelope of homes within a subdivision during a hurricane event.