Architectural Engineering Copyright (c) 2013 California Polytechnic State University All rights reserved. http://digitalcommons.calpoly.edu/aen_fac Recent documents in Architectural Engineering en-us Thu, 16 May 2013 09:44:46 PDT 3600 Roof Drainage: <i>Not my problem ... Maybe</i> http://digitalcommons.calpoly.edu/aen_fac/69 http://digitalcommons.calpoly.edu/aen_fac/69 Wed, 10 Oct 2012 11:11:32 PDT Many structural engineers are surprised to learn that the International Building Code (IBC, 2009) requires the roof structure to be engineered for standing water weight in the vicinity of the drains and scuppers regardless of roof slope. In addition, some low-slope roofs also require special attention for water weight and stiffness for safety against ponding failures or protection against accelerated roofing deterioration. With a mixture of overlapping design disciplines between the architect, plumbing consultant and structural engineer, proper roof drainage is often not fully addressed in building design and can lead to catastrophic collapse.

The author has been involved as an expert consultant in several roof collapses in California due to excessive rain water accumulation, and brings some lessons learned to the profession. This paper provides an overview of the various disciplines involved in transporting rainwater from roofs, and recommendations for engineers to comply with code requirements.

]]> John Lawson Revisions to Tilt-Up Concrete Building Design: The backstory behind changes encompassed in 2009 International Building Code http://digitalcommons.calpoly.edu/aen_fac/68 http://digitalcommons.calpoly.edu/aen_fac/68 Mon, 16 Apr 2012 11:28:26 PDT The 2009 International Building Code (IBC) has in its scope some significant revisions that greatly affect the design of tilt-up concrete buildings, but to the lay engineer it appears that some of these provisions are a step backwards. With the IBC’s referencing standards including ACI 318-08 (concrete) and the 2008 NDS SDPWS (timber), these documents have significant changes that become effective with the adoption of the IBC. We as engineers expect building codes to advance the state of the art with each successive edition. The 2009 International Building Code (IBC) and the Building Code Requirements for Structural Concrete (ACI 318-08) have significant revisions affecting the design of tilt-up buildings, but in some cases not necessarily advancing the state of the art. For example, the latest ACI 318 edition is largely revising slender wall design back to match equations found in the old 1997 UBC. In addition, the latest IBC edition is carving out an exception to an especially troublesome code provision due to an oversight in the adoption process. Other changes in timber design are mostly administrative or incorporating errata from the last code cycle.

This paper provides the background for these changes and reviews their impact to tilt-up concrete building design and wall panel design. In addition, a historical context is provided where if may provide some clarity.

]]> John W. Lawson Finite-Element Limit Analysis of the Tucker High School Gymnasium Roof Failure http://digitalcommons.calpoly.edu/aen_fac/67 http://digitalcommons.calpoly.edu/aen_fac/67 Tue, 03 Apr 2012 10:17:05 PDT The Randolph Tucker High School gymnasium roof failure of 1970 has received much scholarly attention. This study will provide a conclusion to a large body of previously published works by means of limit state analysis of the roof failure using state of the art parametric finite-element modeling. Parametric modeling within a general purpose finite-element analysis program allows for extremely rapid changes to the model because key terms are objects or parameters that can be adjusted internally by the program, rather than laboriously entered by the user. The failure of the roof was investigated by means of a limit state analysis, which accurately captured the cracking of the concrete and the yielding of the reinforcing steel. Concrete creep and shrinkage and relaxation of the prestressing steel were also accounted for. Finally, the authors also studied the idea that camber in the roof geometry might have prevented collapse.

]]> Peter T. Laursen et al. Urban Architecture for Rural East Africa: A Sustainable Solution http://digitalcommons.calpoly.edu/aen_fac/66 http://digitalcommons.calpoly.edu/aen_fac/66 Fri, 17 Feb 2012 12:52:21 PST Craig Baltimore Structural Design Practice Assumptions and Code Interpretation http://digitalcommons.calpoly.edu/aen_fac/65 http://digitalcommons.calpoly.edu/aen_fac/65 Wed, 08 Feb 2012 08:51:57 PST Craig Baltimore Project Managers, Architects, and Engineers--Oh my! An Interdisciplinary Collaboration http://digitalcommons.calpoly.edu/aen_fac/64 http://digitalcommons.calpoly.edu/aen_fac/64 Wed, 08 Feb 2012 08:51:53 PST The Architectural Engineering (ARCE) Program at the California Polytechnic State University in San Luis Obispo is creating a unique and novel interdisciplinary course where architecture, architectural engineering and construction management students collaborate to design and plan the construction of a building structure. The current plan is to develop a default interdisciplinary experience that can be taken by every student and then allow course substitutions for other options as they are created. This paper reports on one of those other options, specifically a unique real world, global, multi-disciplinary experience in East Africa that has resulted from a master’s degree project that incorporated 14 undergraduates into the work. The project is entering its second year, now includes 24 undergraduate students and has the potential to continue well into the future. The students are supporting the Catholic diocese in Same, Tanzania to design a polytechnic school to accommodate up to 500 students. The design experience is allowing students to address the social, political, economic, constructability, and global issues that come from a real world project on a different continent. The students are incorporating local labor capabilities, regional material availability, climate, seismic vulnerabilities, and local customs and traditions into their design. To minimize the costs of construction, operation and maintenance, the student design includes efficient construction methods, energy sustainability and water sustainability.

]]> David Lambert et al. Going Green with Concrete Masonry Grout http://digitalcommons.calpoly.edu/aen_fac/63 http://digitalcommons.calpoly.edu/aen_fac/63 Wed, 08 Feb 2012 08:51:50 PST Concrete, which is a product containing Portland cement, is the second most used building material (after water) worldwide. Masonry grout is similar to concrete except that grout has a high water content and smaller size aggregates. The excess water is immediately absorbed into the masonry units during placement, which lowers the water/cement ratio and allows for a normal hydration process. During the process of making Portland cement, more than 1/5 ton of carbon dioxide is produced for every ton of cement with 60% of the carbon dioxide production due to a chemical reaction. There is currently no viable remedy to reduce the carbon dioxide emission due to this chemical process. To limit carbon dioxide emission from Portland cement production, cement use in concrete products can be reduced (e.g. concrete and grout) [1]. However, the reduction in Portland cement content must not compromise strength or building processes (time).

]]> James Mwangi et al. Capstone Projects: Integrating Industry through Student Leadership http://digitalcommons.calpoly.edu/aen_fac/60 http://digitalcommons.calpoly.edu/aen_fac/60 Fri, 27 Jan 2012 14:56:47 PST Capstone projects provide a unique opportunity for developing student leadership skills while integrating industry partners. While models for including industry partners in capstone projects have been discussed in prior literature, these models focus on faculty leadership in developing industry partnerships. This paper describes a capstone project model that encourages student, not faculty, leadership in engaging industry partners. Factors that influence successful project teaming of students and industry partners are identified and described using case study examples. The successes and difficulties of integrating industry in capstone project via student leadership are explored.

]]> Brent Nuttall et al. Incorporating Constructability in the Design of Masonry Structures http://digitalcommons.calpoly.edu/aen_fac/59 http://digitalcommons.calpoly.edu/aen_fac/59 Fri, 27 Jan 2012 14:56:44 PST The International Building Code (IBC) has now been adopted as the model design code for most states and territories of the United States of America. For Masonry design, the IBC references the Building Code Requirements and Specification for Masonry Structures (MSJC) for material properties, design procedures, specifications and quality control. Individual state codes then amend the two documents (IBC and MSJC) appropriately.

In high seismic regions of the United States, hollow block of concrete masonry units (CMU) are the material of choice in masonry construction. The CMU’s are built using sand, pea gravel, cement and water. CMU is typically delivered to the job site as a individual units usually sixteen inches long, eight inches high and of thickness varying between six inches to twelve inches nominal dimensions as required. Building of a masonry system requires the use of mortar applied at the bed and head of the CMU blocks and grout to fill in the hollow voids in the CMU where steel reinforcement is used. The mortar and the grout are made by proportioning amounts of cement, sand, pea gravel and water as specified by design codes.

This paper presents teaching methods used to teach undergraduate architectural (with emphasis in structural) engineering masonry design courses. The format used exposes the students to instructors that are current consulting engineers and with vast practical knowledge with masonry. The design using masonry at element level is taught in a lecture format. In this format, factors influencing design of the built masonry unit are investigated by building wall units. This hands on “learn by doing” exposes the students to constructability and quality control requirements. Prism tests are also conducted to familiarize the students to the possibility of debonding of the masonry from the mortar. Design using the materials at a system (building) level is then taught in a laboratory format. In this later format, the students prepare complete construction documents (structural calculations, structural plans and structural specifications) for real masonry structures using architectural plans. Understanding of the construction process of masonry structures is highly emphasized in the process of preparing the construction documents.

As a result of this two tier coverage of design of masonry structures, graduates from this program have earned a reputation in California of “being ready on day one” after graduation on designing these types of projects.

]]> James Mwangi et al. Teaching the Design: Timber Shear Walls and Developing Student Engineering Judgement and Intuition Through a Hands-on Experience http://digitalcommons.calpoly.edu/aen_fac/58 http://digitalcommons.calpoly.edu/aen_fac/58 Fri, 27 Jan 2012 14:56:42 PST Engineering judgement and intuition are vital characteristic of the design profession. Engineering judgement and intuition are developed through experience. This experience is gained by designing a building (working with industry disciplines and the owner); analyzing the building (calculations); being part of the construction process (constructability), and walking through the final product (end user). Teaching design means, in part, developing engineering judgement and intuition. This may best be accomplished by incorporating active learning experiences.

For timber and masonry buildings, the shear wall is the lateral resisting system of choice. A hands-on experience has been developed as a simple exercise in constructing shear walls and then assessing the shear walls under a lateral load.

More specifically, in qualitative terms, the idea of wall rigidity is explored; actual construction experience is gained (for many students it is a first time experience in rough framing construction); the behavior and limitations of different wall sheathing is observed directly; insight is gained for code restrictions of different sheathing materials; and system behaviors such as overturning is directly observed.

As a strategy for developing students engineering judgment and intuition, this paper will give a detailed account of the hands-on shear wall exercise. Other educators are encouraged to implement, building upon, or transfer to other topics, the information contained within.

The students are upper level classmen in a timber and masonry design studio (9 hours per week of meeting time on a quarter system) of an architectural engineering program with an emphasis on structural engineering. The authors are licensed structural engineers with over 65 years of practicing experience, who have returned to academia.

The authors believe, from their direct background and experience, that it is important, for design, to begin giving the students non-traditional text book and calculation experiences. Giving the students a non-traditional experience, prior to graduation, is the emphasis of this paper.

]]> Craig Baltimore et al. Preparing Students for the Environment of the Practice of Consulting Engineer http://digitalcommons.calpoly.edu/aen_fac/57 http://digitalcommons.calpoly.edu/aen_fac/57 Fri, 27 Jan 2012 14:56:40 PST In the United States of America, the body of knowledge required for an individual to be allowed to take the engineering licensing examination, which on passing allows the individual to be in responsible charge of engineering projects, is usually defined by laws and regulations of each state. In California, the shortest path taken by most individuals is one where the individual graduates from an ABET accredited undergraduate program; passes the Engineer in Training (EIT) examination and works under the supervision of a licensed engineer for two years (one year if the individual has a Masters degree in relevant field).

In order to better prepare the student to enter the practice of engineering, and thus give the student an immediate level of comfort with the real world environment, practical design needs to be directly incorporated into the teaching of design.

This paper presents teaching methods used to teach undergraduate architectural engineering design courses, where the discipline of concentration is structural engineering. The format used exposes the students to instructors that are current consulting engineers and to courses that are modeled in line with the structural engineering profession. The theory, of construction materials (concrete, steel, masonry and timber) is covered for each material at element level in a lecture format. Design using the materials at a system level (building) is then taught in a laboratory format. In this later format, the students prepare complete construction documents (structural calculations, structural plans and structural specifications) for real projects using architectural plans. This “learn by doing” format has proven-over time-to prepare the students to the same environment that the students face after graduation.

It is generally an accepted fact in the structural profession in California that, graduates from Architectural Engineering program (ARCE) at California Polytechnic State University (CAL POLY) “hit the ground running from day one”. This is attributed to the familiarity, of the design office environment, obtained during their undergraduate education. The familiarity is acquired through the design laboratories taught by design professionals.

]]> James Mwangi et al. Lessons Learned in Sustainable Information and Technology Transfer Considering Culture and Resources http://digitalcommons.calpoly.edu/aen_fac/56 http://digitalcommons.calpoly.edu/aen_fac/56 Fri, 27 Jan 2012 14:56:37 PST In terms of information and technology transfer, sustainability is defined as the ability for a society (or culture) to maintain and incorporate the information and technology in a long term manner without continued outside influence. When a major disaster occurs, like the recent Haiti earthquake, the good intentioned outside relief effort is often immediate with no lasting effects. For example, to have a new building built out of precast panels engineered and manufactured in the U.S., and erected with volunteers from outside of Haiti, will immediately provide for the local community. But will have the people learned in terms of building the next building? It is highly probable the old construction methods and problems will continue. To have a lasting effect, the long systemic causes need to be identified and addressed from within the society or culture - empowerment of the local population has to be developed.

Haiti is an undeveloped nation with the majority of the population below the poverty level. Similar to Haiti, is the population of rural Tanzania. This paper will present the current efforts of sustainable information and technology transfer for the Same Polytechnic School in rural East Africa. And it is hoped the parallels in the two cultures can be used to provide insight for long term solutions to the built environment of Haiti.

]]> Craig V. Baltimore Mixing Numbers and Letters: Collaboration Between Engineering and English to Improve Graduate Student Work http://digitalcommons.calpoly.edu/aen_fac/55 http://digitalcommons.calpoly.edu/aen_fac/55 Fri, 27 Jan 2012 14:56:35 PST This paper will describe the issues and process of developing an introductory course in graduate writing and communication skills in conjunction with the industry of professional consulting engineering. The course was developed through a collaboration of English and engineering faculty and the collaboration is maintained in the teaching of the course. Innovative techniques incorporated into the course development include a four-pronged approach: 1) use of best practices for Writing in the Disciplines; 2) development of and focus on a multi-faceted collaborative model (Engineering and English, university and industry, students and faculty, industry and students); 3) team-teaching by engineering and English faculty members for the initial graduate research course; and 4) emphasis on the quality of the thesis project content in terms of the research itself, analysis and synthesis of that research, and effective communication of the results. Accountability and assessment of students’ work includes development of the thesis project statement and presentation of their work to a body of their peers; presentations and evaluations by departmental faculty; and round table talks with industry. This system of accountability and assessment have shown marked improvement in the communication skill set often minimized in both undergraduate and graduate engineering education.

]]> Craig Baltimore et al. Knowledge Transfer and Adobe Block http://digitalcommons.calpoly.edu/aen_fac/54 http://digitalcommons.calpoly.edu/aen_fac/54 Fri, 27 Jan 2012 14:56:33 PST Craig Baltimore "Tilt-up Building" and "Tilt-up Wall Panel With Openings" http://digitalcommons.calpoly.edu/aen_fac/53 http://digitalcommons.calpoly.edu/aen_fac/53 Thu, 22 Sep 2011 14:05:12 PDT John W. Lawson Concrete Slender Wall Design – Back to the Future http://digitalcommons.calpoly.edu/aen_fac/52 http://digitalcommons.calpoly.edu/aen_fac/52 Thu, 02 Jun 2011 13:17:49 PDT Slender concrete walls incorporated into tilt-up construction
over the past 60 years have performed remarkably well under
out-of-plane wind and seismic loads. While issues associated
with seismic wall anchorage gave this form of construction a
black-eye in the early days, the concrete walls themselves
have always performed very well even as far back as their
first use in the early 1900s. Yet the height-to-thickness
limitations in 1985 and earlier model building codes were
proved irrational and were removed. We as engineers expect
building codes to evolve and advance the state of the art with
each successive edition. The latest edition of ACI 318-08 has
significantly revised the slender walls design procedures, yet
not necessarily advancing the state of the art. The latest ACI
318 edition is largely revising slender wall design back to
match equations found in the old 1997 UBC.
This paper revisits the historical effort SEAOSC played in the
development of the original slender wall provisions in the late
1970s, and why ACI is now revising their slender wall design
provisions to agree with concepts developed over 30 years
ago by SEAOSC. While these original concepts were based
on empirical data from full-scale tests conducted in the early
1980s, only within the last five years have we really begun to
fully understand the behavior of these thin concrete members
when subjected to combined axial load and large horizontal
forces.

]]> John W. Lawson et al. Tilt-up Buildings http://digitalcommons.calpoly.edu/aen_fac/51 http://digitalcommons.calpoly.edu/aen_fac/51 Fri, 20 May 2011 11:02:57 PDT UBC 97 and ACI 318-02 Code Comparison - Summary Report http://digitalcommons.calpoly.edu/aen_fac/50 http://digitalcommons.calpoly.edu/aen_fac/50 Tue, 17 May 2011 15:31:40 PDT Introduction

Recognizing there have been questions on the differences between the alternate slender wall design procedures in 1997 UBC and in ACI 318-02, the SEAOSC Board authorized a Task Group to provide a comprehensive review of the two design procedures. The ACI procedure was adopted by IBC 2000 and subsequent code editions. As quoted in ACI 318R-02 Commentary Section R14.8, Section 14.8 is based on the corresponding requirements in the UBC and experimental research of the Test Report by SCCACI-SEAOSC.

This summary report includes review of source documents, code comparison, and background of the design provisions under UBC and under ACI, respectively. A comprehensive review of the 1980 test data was made in addition to analytical comparison of sample wall panel design under each of the two procedures. Pursuant to the comparative design and validation of the original data, a list of findings is presented in the Report. Other design considerations though not part of the code comparison are discussed in order to encourage further studies by other groups. The report concludes with recommendations to SEAOSC Board and proposed changes to ACI.

Code Comparison

Under 97 UBC Section 1914.8, the cracked moment is based on fr = 5 √ f ´c.; and in ACI 318-02 Section 14.8, the cracked moment is based on fr = 7.5 √ f ´c. This also means that the Mcr (UBC) = 2/3 Mcr (ACI) in the application of the two design procedures. In the 97 UBC, a linear interpolation between Δcr and Δn is permitted in obtaining Δs in order to simplify the slender wall panel design for Ms > 5 √ f ´c Ig/yt. The ACI procedure employs effective moment of inertia and a magnified moment for the combined moment due to lateral and eccentric vertical load, also know as the P-Δ effect. Table 1 gives section by section comparison between the alternate slender wall design procedures.

Review of 1980 Test Data

This Task Group was able to review and re-analyze the original test data. Verification of the 1980 data using adjusted lateral force and deflection data was performed. The analytical result follows closely with the bilinear load deflection characteristic. Lateral deflection increases rapidly when the moment exceeds two-third (2/3) of Mcr (as defined by ACI). The calculated moments for each of the twelve test panel correlate closely with the empirical test data. The load deflection curves and plots for the low axial loads versus moment interaction curve further validate the UBC design procedure. ACI needs to improve its methodology in computing Mu and Ie so that computed results would follow a bilinear load deflection characteristic.

Summary of Findings

Summary of comparative design examples is given on Table 5. Design based on ACI procedure is normally controlled by strength with service load deflection less than Δcr. ACI procedure significantly under-estimates service load deflection in comparison to the UBC procedure with increase lateral force and/ or axial load. Where wall panel design based on ACI procedures meets strength and deflection limit, the corresponding wall panel calculation based on UBC procedure may exceed the deflection limit.

Recommendations

  • To calculate service load deflection, use E/1.4 for earthquake forces
  • Recommend to appropriate enforcement agencies that adoption of the 2003 IBC provisions on alternate design of slender wall procedure should incorporate proposed changes to ACI 318-05 Section 14.8.4.
  • Modification to ACI 318-05 Section 14.8.4 -delete equations (14-8) and (14-9) and the last paragraph in total, and replace with the following after the first paragraph:

“Δs = 0.67Δ cr + (Ms –0.67Mcr )(Δn –0.67Δcr)÷ (Mn-0.67Mcr); for Ms > 0.67Mcr (14-8)

Δs = 5 Ms lc2 ÷ (48Ec Ig) ; for Ms<.67Mcr (14-9)

  • Send a letter to ACI-318 addressing the concerns in using the ACI alternate design of slender wall procedure and requesting ACI 318 to correct statements under Commentary R14.8.

]]> Chukwuma Ekwueme et al. Using the Hyatt Regency Skywalk Collapse Case Study in Engineering Education. http://digitalcommons.calpoly.edu/aen_fac/49 http://digitalcommons.calpoly.edu/aen_fac/49 Tue, 17 May 2011 15:31:33 PDT To this day, the 1981 skywalk collapse in the Kansas City Hyatt Regency resulted in the worst loss of life from a structural engineering mistake in United States history. While many important engineering lessons can be drawn from this disaster, it is just as important to recognize the broader lessons learned in the design and construction process as a whole that can be successfully brought into the classroom. Numerous organizations have undertaken the task of envisioning how engineering education can meet the demands of the future. ABET’s baccalaureate degree accreditation criteria, ASCE’s Body of Knowledge and Body of Knowledge 2 as well as the National Academy of Engineering have documented the need to change engineering education from its historical focus on technical content knowledge to include greater emphasis on professional issues and to integrate engineering practice into education. To this end teaching methods such as project based learning, active learning and the use of case studies are being explored to address these broader learning outcomes while actively engaging students. Because of the attraction students have in extraordinary events, the Hyatt disaster provides an ideal backdrop to introduce many of the professional issues needed to broaden the undergraduates’ learning experience. This paper discusses the use of the Hyatt Regency skywalk collapse in design coursework with specific application to third and fourth year civil and architectural engineering student learning. Besides the traditional concepts of load flow analysis and member design, broader concepts relating to professional roles and responsibilities, design team interplay, the design process, the construction process and professional practice ethics are emphasized.

]]> John W. Lawson et al. Using Case Studies to Characterize the Broader Meaning of Engineering Design for Today’s Student http://digitalcommons.calpoly.edu/aen_fac/48 http://digitalcommons.calpoly.edu/aen_fac/48 Tue, 17 May 2011 15:31:28 PDT Numerous organizations have undertaken the task of envisioning the education required to meet the engineering demands of the future. The ABET study EC2000, ASCE’s Civil Engineering Body of Knowledge and Body of Knowledge 2 and the National Academy of Engineering have documented the need to change engineering education from its historical focus on technical content knowledge to include greater emphasis on professional issues and to integrate engineering practice into education. To this end teaching methods such as project-based learning, and the use of case studies are being explored to address these broader learning outcomes. Case studies in particular facilitate telling the stories of professional practice. This paper discusses the use of engineering case studies in design coursework with specific application to third year architectural engineering student learning. Introduction, application and discussion of several case studies are presented in the context of teaching building structural design. Along with the technical execution of system and member selection, computer analyzes and structural detailing that occur in these courses, broader concepts relating to professional roles and responsibilities, design team interplay, the design process, the construction process and professional practice ethics are investigated. The advantages of this altered approach to teaching engineering design are discussed.

]]> Pamalee A. Brady et al.