Preliminary CLT-LiFS Investigation
It is envisioned that two types of structural systems – one emerging and one traditional – can be optimally combined to exploit their beneficial features and yield a new building system for tall wood structures. Traditional light-frame wood construction is light, as its name implies, and emerging cross-laminated timber has combined bearing and lateral-force-resisting capabilities. The overall project involves a long-term research effort for the new Cross Laminated Timber – Light Frame Wood System (CLT-LiFS). The experimental studies conducted so far had a goal of better understanding the synergies and challenges of combining CLT rocking panels with light-frame wood shearwalls; specifically, identifying the technical barriers that exist to their development. As a preliminary study, an experimental investigation of the behavior of a post-tensioned rocking CLT wall specimen was performed using a single CLT panel (2-feet by 8-feet by 5.5-inches) post-tensioned to the foundation using a 0.6-inch diameter post-tensioning strand.
This study included testing of two identical specimens rocking on a CLT base and steel base, respectively. The CLT wall panel was subjected to reverse cyclic loading using a 55-kip capacity MTS actuator. The load protocol suggested by ACI ITG 5.1 (ACI Innovation Task Group 5, 2008) for post-tensioned concrete walls was used with modification to arrive at the loading protocol. The CLT panel was subjected a maximum lateral drift of 4.5 percent, in 0.25 percent increments, with three cycles at each lateral drift. The experimental program demonstrated the excellent performance and considerable impact of foundation stiffness (construction practice) on the design capacity. When the CLT panel was used as the foundation, damage to the CLT base occurred, leading to higher energy dissipation. From these preliminary studies, it is clear that CLT-LiFS is a promising seismic-load-resisting system that can be used in building construction provided the deformation compatibility and beneficial features of each component still exist in the hybrid system. In order to have deformation compatibility and ensure the beneficial features of each component still exist in the hybrid system, several studies of how to combine these two types of structure into a hybrid system are needed.
Next Generation Hybridized Wood Buildings
As part of this study, two tests on full-scale CLT panels to study the creep behavior of post-tensioning CLT panels are being conducted. These tests are being carried out in the walk-in environmental chambers at the University. In the creep tests, a CLT panel is post-tensioned using a hydraulic jack placed at one end of the panel with the other end of the panel supported by springs. The post-tensioned force applied on the panels during creep testing is approximately equal to the gravity load transferred to the panels in tall wood-frame buildings plus the post-tensioning force in the tendon. The panels have been placed in the environmental chambers where temperature and moisture can be programmed to vary with time. The temperature and moisture are programed for several hundred cycles to simulate environmental change during the days and nights of different seasons of the year.
It is anticipated this will provide data on how the post-tensioning force in a CLT panel changes due to changes in environment. This will help better predict the behavior of CLT panels during an extreme event. The data from these tests will be used in a numerical model to predict creep behavior of CLT panels. The results from the numerical model will be considered as the initial condition for post-tensioned rocking CLT panels in the CLT-LiFS system prior to extreme events such as an earthquake, hurricane, or tornado.
Test-Bed for Real-Time Hybrid Simulation
The test bed, which contains an adjustable mass box, spring and damper driven by a hydraulic actuator, is being used to facilitate the development of real-time hybrid simulation (RTHS) in the LSSL. This capability will permit future investigation of the real-time dynamic response of large or full-scale structural and mechanical components.
NASA Disruptive Tuned Mass
To solve a severe vibration issue on the Ares I launch vehicle, NASA Marshall Space Flight Center (MSFC) developed the Fluid Structure Coupling (FSC) technology to control and leverage the coupling between on-board fluid propellants and the launch vehicle. It is a highly efficient and passive method to control the manner in which fluids and structures communicate and dictate the behavior of the system. This controlled coupling allowed NASA to fundamentally alter the dynamic attributes of the launch vehicle and solve this complex vibration issue.
Recently, NASA expanded the early analytical and experimental results from FSC to purely mechanical systems, which has led to a new class of tuned mass vibration control system – the Disruptive Tuned Mass (DTM). This new vibration control system has the potential to reduce the vibration of civil engineering structures, such as buildings and bridges, under extreme dynamic loads due to natural hazards. For example, in a multistory building, water from a rooftop tank or swimming pool can be used to mitigate seismic or wind-induced vibrations by adding a DTM device that controls how the building engages the fluid mass.
Recently, a small DTM prototype using lead mass was developed by NASA engineers, and was mounted on a two-story steel frame for testing on the earthquake simulator located in the LSSL. Preliminary tests of the device have provided promising results and have resulted in UA faculty working with NASA MSFC personnel to develop a long-term research program for further testing of this and other related devices.
RAPID Experimental Facility (RAPID EF)
A team of CSI faculty members have submitted a proposal to the National Science Foundation to develop and operate a premier post-disaster rapid response experimental facility (RAPID EF). This facility will support researchers and practitioners in collecting perishable data in the aftermath of earthquake and wind-related natural disasters. Field data collected through this EF will be uploaded to a repository that can be used by the general scientific and broader communities.
NSF and others commonly deploy small teams of researchers to study specific aspects of a disaster. Currently, perishable data is collected by different teams, but the data is not integrated and stored in a standard unified format, i.e. no standardized ontology. The proposed RAPID EF will design, develop and implement an open-source modular approach that supports earthquake and wind-related perishable data collection, real-time distribution as well as facilitate long-term data storage at the NHERI Cyberinfrastructure (CI) awardee (UT-Austin) to maximize data reuse to further science in support of disaster mitigation. The UA team was one of only two teams to receive a reverse site visit and is currently waiting for final disposition of the award.
In the event of a large-scale disaster, a multidisciplinary team is put together for deployment for post-disaster reconnaissance. The team consists of various university academics, industrial professionals, and trained GIS Research Group students. The team works together to collect geo-referenced data including photographs, 3D scans, and video of damage, as well as worksheets, calculations, and voice messages while studying the affected area. Our inventory contains geo-referenced data for recent tornadoes in Tuscaloosa, AL, Moore, OK, and Joplin, MO. The data collection methodology is extensible to other researchers, and the data inventory is freely available and accessible through developed online portals. The data is used to create damage contours, wind speed maps, and other research-based spatial definitions of damage.
The GIS Research Group holds monthly training sessions to keep our research staff trained, educated and ready to safely and efficiently deploy in the event of a natural disaster. Equipment training is regarded with high importance for safety, and includes training on the following: GPS devices, cameras, and Light Detection and Ranging (LiDAR) laser scanning. The outcome is to preserve useful descriptions of damage for engineering analysis. These data can be used to further the state of engineering practice, study community resistance and resiliency, and our hope is to leverage our datasets in order to collaborate with others in order to open new avenues of research.
Recycled Material Web Map: Connecting Consumers to Producers
The Recycled Material Web Map project will produce an on-line tool that connects producers and consumers of nonhazardous recyclable material. The Recycled Material Web Map is comprised of three core layers: stockpiles, regulations, and case studies. The stockpile layer allows facility managers to login and enter or update information about recycled material stockpiles including type(s), application, and availability. The regulation layer includes both environmental regulations and Department of Transportation specifications pertaining to the beneficial reuse of recycled material based on specific location, type, and application. The case study layer locates projects that successfully utilized recycled materials and includes information regarding the type, application, volume data, and the facility that supplied the recycled material. Consumers can pinpoint the location of a construction project, search for sources and quantities of recycled material that meet project specifications, and identify applicable regulations. The web map utilizes search capabilities to locate facility stockpiles and minimize transportation costs that typically dictate the use of large volumes of materials. The Recycled Material Web Map bridges the information gap between producers and consumers of recycled material and promotes the use of recyclable material, thereby preserving our limited natural resources.
GeoGIS is a web-based geotechnical database management system created for the Bureau of Materials and Tests of the Alabama Department of Transportation (ALDOT). The purpose of GeoGIS is to provide a fast and efficient method of storing and retrieving geotechnical information for ALDOT engineers and consultants. A map displaying projects and a document search page based on document attributes provides users the ability to quickly locate information. A document upload page allows documents to be added to GeoGIS. Access to the GeoGIS website is limited to authorized users determined by ALDOT. A four tiered hierarchy of user classifications determines access privileges to various website features. The lowest level, General User, can view the map and retrieve documents. Consultants inherit the privileges of the General User, and have the ability to upload documents. ALDOT Engineers inherit Consultant privileges, and have the ability to approve uploaded documents and initiate projects to be displayed on the map. The highest level, Administrator, inherits all previous privileges and has the ability to manage user accounts. To date, over 5200 documents have been stored in GeoGIS spanning about 1200 projects across the state of Alabama. The GeoGIS website is currently being utilized by ALDOT and ALDOT consultants. GeoGIS improvements continue to add website functionality and documents on a daily basis.
Tuscaloosa Resilience Project
The scope of the Tuscaloosa Resilience Project includes documenting and analyzing the rebuilding efforts in the areas affected by the April 27, 2011 tornado. This includes implementing a GIS-based methodology to geolocate inspection photographs in the city and methods to document the change in land use, building stock, and other aspects of the city makeup. The project is a collaboration of the Civil Engineering department and the Alabama Center for Insurance Information and Research (ACIIR).