Andrea Surovek

Fundamental Behavior of Steel Beam-Columns and Columns under Fire Loading: Experimental Evaluation

This paper presents the results of experimental investigations conducted to determine the fundamental behavior of steel members under fire loading. A total of eleven full-scale steel members were tested under combined thermal and structural loading. First, five A992 steel beam-columns (W10×68) were tested to determine their fundamental moment-curvature responses at elevated temperatures and different axial load levels. The experimental approach involved the use of radiant heating and control equipment to apply the thermal loading, and close-range photogrammetry combined with digital image processing techniques to measure the deformations (curvature) in the heated zone. Next, six A992 steel wide-flange (W8×35 and W14×53) columns were tested to determine their inelastic buckling behavior and axial load-displacement responses at elevated temperatures. A self-reacting test frame was designed to subject the column specimens to axial loading and heating. The thermal loading was applied by using the same type of...

Design Wars: Developing student creativity through competition

Design Wars was developed as a multi-disciplinary design competition in which teams of students receive the same assignment, materials, technology tools for communication and time to complete the project. The student teams were separated into two groups - the documentation team (in the “design office”) and the actualization team (on the “build floor”). They were tasked with designing, constructing, and documenting an engineered solution to a complex problem on site within eight hours, with all design decisions communicated between the two groups via mobile computing. The competition was developed to challenge the students creativity and communication skills; judging was based on the elements of creativity including originality, flexibility, fluency, elaboration and aesthetics. Additionally, students were judged on their ability to document their teams decisions and alternative solutions. Because creativity in engineering is unsuccessful without functionality, the final projects were penalized if they failed in execution.

The Direct Analysis Method: Bridging the Gap from Linear Elastic Analysis to Advanced Analysis in Steel Frame Design

Developments in analytical software and computer hardware over the past few decades provide engineers with powerful tools for more realistically considering the behavior of steel structures . More sophisticated methods of analysis offer significant advantages in steel frame design by eliminating the need to calculate effective length factors and more directly including factors that affect system and member strength . One such method, the Direct Analysis approach, accounts for the effects of member inelasticity and frame imperfections in the assessment of both member and system strength. The latter is achieved by directly including t hese effects in calculating the distribution of forces in the structural system . This approach is applicable for use in the design office using commercially available software and it is applicable to a wide variety of structural problems including braced frames, moment frames and mixed systems. Just as importantly, the approach it allows for a natural transition between current elastic analysis procedures and the future availability of second-order inelastic analysis programs suitable for use with an adva nced analysis-design approach.

Special Issue: Commemorating 10 Years of Research since 9/11

This special issue of the Journal of Structural Engineering commemorates 10 years since the attacks of September 11, 2001, by focusing on research that was motivated by the impacts of events of that day. Primarily, in response to the collapse of the World Trade Center towers, the damage and collapse of neighboring structures and the damage to the Pentagon, national organizations and structural engineers have performed substantial amounts research in the area of progressive collapse with an emphasis on the response of structures to extreme loads. The ultimate objective of this research is to provide the means to design more robust and redundant structures that can resist progressive collapse under extreme loads, such as blast, impact, and fire, by considering both member and system response to extreme events and increasing the database of experimental results. This special issue focuses on some recent research in these areas. The papers and their list of references combined are a rich source of information and a state-of-the-art representation of structural engineering for extreme loads. The first seven papers in this issue focus on the topic of resiliency and robustness. Although the Department of Defense (DoD) has been focused on collapse prevention since before 9=11, they have done significant research since that event. The first paper, by Stevens et al., highlights the work that lead to development of the Unified Facilities Criteria (UFC) 4-023-03, Design of Buildings to Resist Progressive Collapse. Both experimental and analytical investigations of progressive collapse are considered in the next three papers. Sadek et al. focus on steel and concrete moment frames with a focus on beam column subassemblages in the event of a column removal. Sasani et al. present results of an experimental and analytical investigation of an 11-story concrete structure with initial damage. Williams and Williamson look experimentally and analytically at the topic of concrete bridges subjected to blast. The next three papers look more at the analytical and probabilistic side of progressive collapse. El-Tawil investigates the impact of modeling decisions on the analytical response of a 10-story steel structure and highlights the importance of the floor system in the analysis. Xu and Ellingwood look specifically at whether preNorthridge steel moment frames meet UFC requirements for structural integrity using probabilistic modeling of the connections. Kanno and Ben-Haim consider structural redundancy and its effects on robustness of the structure by considering concepts of strong and weak redundancy. The events of 9=11 pointed to large knowledge gaps in the response of structures to fire; and since then, the number of researchers and publications in this field have grown. One example is a paper by Braxtan and Pessiki, who developed the first set of experiments that examine the structural effects of removed fire protection in a fire following an earthquake. In addition to describing the experiments, finite-element analyses show how spray fire protection damage on the steel beams adjacent to the steel column causes an increase in temperatures in the column. Columns are integral to stability in a building; and in the case of fire, the columns can develop unanticipated moments and thus respond as beam-columns, which are subject to both axial loads and moments. Varma et al. tested several steel wide-flange columns under combined axial load and moment conditions to determine their fundamental moment-curvature responses at elevated temperatures and different axial load levels. Other steel wide-flange columns were tested to determine their inelastic buckling behavior and axial load-displacement responses at elevated temperatures. Columns on a building perimeter respond as beam-columns in a fire because of the thermal gradient that induces moment in the rotationally restrained column. Quiel et al. present a two-pronged procedure to predict the behavior of the perimeter column, considering both the individual member response (including thermal gradients) and the global response (including the interactions of adjacent members). This closed-form procedure predicts the perimeter column response (demand) and capacity. Steel beams acting compositely with concrete slabs contribute significantly to the load-carrying capability of floor systems under fire. But how much does the slab contribute to the load-carrying capacity, what are the failure mechanisms, and under what conditions is the slab most beneficial? To begin to address some of these questions, Varma et al. experimentally investigated the structural behavior of thin composite floor systems subjected to combined gravity loads and fire loading. They studied parameters such as shear connection types, fire scenarios, and fire protection scenarios to evaluate the effects of each on fire performance. The companion papers by Cashell et al. study the ultimate behavior of lightly reinforced concrete floor slabs under extreme loading conditions. Particular emphasis is given to examining the failure conditions of idealized composite slabs which become lightly reinforced in a fire situation because of the early loss of the steel deck. The first paper focuses on experiments that were conducted at ambient temperature and represent an essential step toward quantifying the behavior under elevated temperature conditions. The second paper describes numerical simulation of the tests and suitable analytical models for predicting various failure conditions in slabs, including the condition of elevated temperature. This special issue is a joint effort of the Fire Protection and Structural Members Committees of the Structural Engineering Institute (SEI) Technical Activities Division. These two committees; and the Committees on Blast, Progressive Collapse, Composite Construction and Connections; were instrumental in developing the pool of authors and reviewers for this issue. We are most thankful to the reviewers, who under tight time constraints, made careful evaluations of the submitted manuscripts and provided valuable feedback. We would also like to thank Dr. Sherif El-Tawil, chief editor, for his support and efforts, as well as the ASCE production offices for their extra attention to this issue as we approached deadlines.

Direct Second-Order Analysis for the Design of Steel Structures

Basic guidelines are needed to aid engineers and structural analysis software developers in understanding the requirements for capturing member and system strength limit states within advanced analysis models. This paper discusses a current to develop proposed guidelines for the use of direct second-order inelastic analysis for the design of planar steel frames. These guidelines, when completed, will provide the designer with guidance in analysis and modeling requirements, as well as design considerations (e.g. appropriate factors of safety) such that the behavior and strength of the overall system and limit states of individual members are checked concurrently without the need for individual specification member strength checks.

Cultural considerations in service learning with American Indian Reservation community stakeholders

In the process of designing engineered systems, it is not uncommon for engineers to underestimate or altogether ignore the societal and cultural context of the problem. This is particularly true when designs are developed to solve world problems; a lack of societal consideration leads to implementation failures when engineers from developed countries attempt to design solutions for people in developing countries rather than working with them. It has been increasingly recognized in literature that stakeholder participation is critical for designing sustainable solutions. However, translating social and cultural values and stakeholder participation into engineering education remains an elusive challenge for educators. A similar challenge exists with engineering design for American Indian Reservations; however, this challenge is amplified due to a long history of racial tensions, biases, and political oppression that leads to American Indian distrust of mainstream engineers. This work in progress describes an ongoing engineering design project that is designed to meet the needs of the Pine Ridge Indian Reservation (PRIR) while: (a) challenging students at a mainstream university to design within an appropriate cultural context, (b) incorporating stakeholder participation and (3) increasing opportunities and interest in Native American participation in engineering. Dialogue between community members of the Pine Ridge Indian Reservation (PRIR, where OLC is located), faculty and students of the Oglala Lakota College (OLC) Tribal College, and faculty and students at the South Dakota School of Mines and Technology (SDSMT) have identified that the PRIR community is interested in collaborating on the design, research, and testing of a sustainable, renewable-energy based food production system. The system should not only to meet the community needs for safe and healthy foods, but also serve as a potential source of economic development for the community. This project includes an extensive partnership and has a strong focus on achieving sustainable design and business development through a multi-disciplinary advisory team. Students from South Dakota School of Mines and Technology (SDSMT) have partnered with faculty and students from the Oglala Lakota College (OLC) on the functional design of a renewable-energy based structure for economic development. The design team is advised by faculty at both institutions, as well faculty and experts representing other synergistic projects on PRIR, including an on-going NSF engineering educational effort, the Native American Sustainable Housing Initiative (NASHI), based at University of Colorado Boulder (CU Boulder), to share climate station data and energy monitoring expertise, and Thunder Valley Community Development Corporation, a sustainable community grant holder located at Sharps Corner, South Dakota, just 8 miles from the OLC campus, to share cultural knowledge and values and business development strategies. The paper describes the lessons learned by students and educators when consideration of culture and stakeholder investment become significant components in an engineering design.

Behavior of Steel Columns under Fire Loading

This paper presents the behavior of A992 wide flange steel columns under fire loading. Experimental tests were conducted to investigate the structural-thermal response of steel columns subjected to axial loads and elevated temperatures. Two identical W14X53 specimens were tested under (i) non-standard fire loading to determine the axial load capacity at elevated temperature and (ii) standard fire loading to determine the buckling temperature of the axially loaded steel column. For the non-standard fire test (Test I), the monotonically increasing axial load was imposed on the steel column under steady-state heating condition. For the standard fire test (Test II), the steel column carrying the sustained axial load was tested under transient heating condition. The structural-thermal responses of steel columns observed in Test I and Test II were compared including column end rotations, lateral and axial displacements, and steel temperatures. The measured column buckling behaviors were also compared to those obtained by 3D finite element analyses. The results indicated that the end rotations and displacements of the steel column before buckling were affected by the sequence of applied loading. Both Test I and Test II provided the similar prediction of axial load capacity and buckling temperature of the steel columns.

Promoting Sustainabiliy In Engineering Through EPICS Program

Future engineers must be able to incorporate sustainability into all aspects of their designs to meet the increasing demands for the world’s resources. Consequently, engineering educators have been challenged to integrate sustainability into existing curricula. Sustainability is a particularly complex problem requiring innovation, which often stems from diversity. Service learning programs have been shown to be an attractive and effective method to blend sustainability into engineering education curricula while also encouraging diversity in engineering. In particular, Engineering Projects in Community Service (EPICS) is a well-established service-learning program at 24 universities that has been known to accomplish this by presenting engineering in social context and engaging students in designing solutions to real world problems. This paper describes the complex problem of sustainability and its relationship with diversity and student attitudes in engineering, demonstrates the EPICS program’s ability to promote sustainability and diversity in engineering, presents a research plan to evaluate its effectiveness, and provides preliminary results.

Section Characterization of Wide-Flange Steel Sections Subjected to Combined Thermal and Mechanical Loading

AbstractThe NIST Building and Fire Research Laboratory developed 29 recommendations for research based on the findings from the investigation of the World Trade Center (WTC). This paper discusses the results of a collaborative research effort conducted to address recommendation R9.1 from that report, namely to “Develop and validate analytical tools, guidelines, and test methods necessary to evaluate the fundamental behavior and fire performance of components and the structure as a whole system.” Specifically, it describes the development of a closed-form analytical model to represent moment-curvature-thrust-temperature (M-Φ-P-T) behavior of steel beam-columns in strong or weak-axis bending. The model considers uniform temperature distributions through the cross sections, and it is developed from parametric studies using a fiber-based analytical approach calibrated to experimental and finite-element results. The section-constitutive model was developed to provide a computationally efficient alternative to ...

Experimental Investigation of Steel Beam-Columns Under Fire Loading

This paper presents the experimental investigation of steel beam-columns under fire loading. Experimental tests have been planned to examine the fundamental behavior of steel beam-columns. Test specimens were sequentially subjected to: (i) constant axial loading, (ii) thermal loading on the plastic hinge region followed by ASTM E119 timetemperature (T-t) curve, and (iii) monotonically increasing flexural loading. The experimental approaches involved the use of: (a) innovative radiant heating and control equipment to apply thermal loading instead of using a conventional furnace and (b) digital image processing technique incorporated with close- range photogrammetry to measure the deformation and curvature over the heated region. The measured axial forcemoment-curvature-temperature (P-M-Φ-T) responses of the steel members were compared to those obtained by 3D finite element models and analyses.