Introducing Structural Engineering

At DLSU-Manila, we hold a forum promoting the various specializations in civil engineering - Hydraulics and Water Resources (HWR), Transportation Engineering (TRE), Construction Technology and Management (CTM), Geotechnical Engineering (GTE) and Structural Engineering (STE). I was tasked to present the STE specialization. To introduce the STE specialization, I created a short video using Power Director and presented this during the forum.

So you want to be a structural engineer? Watch the video and explore the world of the structural engineer and how he changes the world.

Tales of Disasters: Earthquake!

Here is another film made by No Strings for programmes in South East Asia and funded by Trocaire. The movie is about Badu and the Little Girl who experienced an earthquake. It is a movie on earthquake preparedness and response. Watch this with your kids.

This video was accessed at http://cogssdpe.ning.com/.

ASEP 14th International Convention - Call for Abstracts

The Association of Structural Engineers of the Philippines, Inc. (ASEP) on its 47th year is hosting the 14th ASEP International Convention with the theme, “Structural Engineering: Coping with the Global Crisis” on May 21-22, 2009. In this regard, you are invited to submit an abstract and full paper (later) for presentation during the convention.

Topics of papers on structural engineering which address innovative approaches of coping with the global crisis and problems - financial, political, environmental, climate change, natural disasters, terrorism, poverty and sustainability - are welcome.

Specific topics include: Performanced-based design, Retrofitting and Strengthening, Structural Failures, Structural Risk, Natural Hazards and Disaster Rsis Mitigation, ISO Standards and Codes of Practice, Earthquake and Wind Engineering, Value Engineering, Engineering Ethics, Urban Planning and Infrastructure Development, Fire, Impact and Blast Loads, Case Studies on High-Rise Buildings and Long-Span Bridges, Prestresses and Pre-cast Construction, Foundation and Geotechnical Issues.

Deadline of Submission of Abstracts: 14 February 2009

Deadline of Submission of Full Papers: 24 March 2009

Send abstracts to: asep14aic@gmail.com

Disasters and Development

One of the videos in "Understanding Earthquakes and Disasters: Photo-Video Presentations for Public Awareness and Education" is entitled "Disasters and Development."

Natural disasters occur if society is highly vulnerable to the hazards. When a disaster occurs, the development and the economy of the country and local community is affected. As a country develops, the population increases and more infrastructures are constructed, and these may increase vulnerability to the hazards. . Understanding the relationship between disasters and development is important in designing a comprehensive disaster risk mitigation program.

Tales of Disasters: Tsunami!

I joined a social network - Coalition for Global School Safety & Disaster Prevention Education and learned of the various initiatives around the world in promoting disaster awareness to the public especailly in schools through the world wide web. I found interesting videos created by No Strings, a group of puppeteers who use colorful and engaging adventure films to teach life-saving messages to children.

Here is the first video on Tsunami. The story centers on Badu, a likeable but lazy villager who teaches by negative example and a Little Girl who is aware of natural hazards and disasters and their signs and effects. Watch this video with your kids as this is really very informative.

Designing for Safety & Stability Leads to Sustainability

Today, there is an increasing demand for engineers to focus their efforts on the protection and preservation of the environment. The civil engineering community, which includes structural engineers, plays a major role in maintaining the balance and harmony between the built and existing natural environment. The built environment, which includes infrastructures such as residential houses, high-rise buildings, long-span bridges, roads and expressways, and large civil structures like dams and reservoirs, provide for a livable atmosphere for all. However, the impact of these infrastructures on the natural environment especially in natural hazard-prone countries like the Philippines should be a concern. Richardson (2002) summarizes the realities of infrastructure impact on the environment as follows: It is said that 50% of the world population lives in cities today and this may grow to 75% by 2030. Cities are said to cause 75% of the world’s pollution and consume 75% of the world’s energy. Buildings are reported to produce 40% of the world’s CO2, consume 50% of the energy derived from fossil fuels, consume 3 billion tons of raw materials in construction each year and consume 75% of all energy used through artificial lighting, heating and cooling every day. 25% of all wood harvested is used in building construction.

The negative impact of infrastructures on the environment aggravates especially when natural disasters occur. Natural disasters like earthquakes, floods, typhoons, tsunamis and landslides spoil both the built and natural environment. Aside from causing numerous deaths and injuries to people, natural disasters had caused the destruction of important infrastructures such as buildings, bridges and roads and devastation of nature which contributed to environmental degradation. The 1999 Chi-Chi earthquake in Taiwan caused 2,415 deaths, 1,441 severely wounded, US$9.2 billion worth of damage, 44,338 houses completely destroyed and 41,336 houses severely damaged. The 2001 Gujarat earthquake in India was the most devastating earthquake in India in recent history. The quake destroyed 90 percent of the homes in Bhuj, several schools, and flattened a hospital. Gujarat's commercial capital and a city of 4.5 million, as many as 50 multistory buildings collapsed and several hundred people were killed. In the July 16, 1990 earthquake in the Philippines, damage to buildings, infrastructures, and properties amounted to at least P 10B. The Hyogo-ken Nanbu earthquake in Japan which hit the city of Kobe and surrounding areas in Hyogo prefecture on January 17, 1995 cause the collapse of nearly 55,000 houses in the city of Kobe. The cost of reconstruction of buildings alone was roughly estimated at between US $61-70 billion.

As a consequence of the destruction brought about by natural disasters, the natural resources, materials and energy that have been utilized in constructing these infrastructures have been put to waste. Moreover, the large amount of disaster-caused waste and debris poses another environmental problem. The most severe natural disasters generate debris in quantities that can overwhelm existing solid waste management facilities or force communities to use disposal options that otherwise would not be acceptable.

How may structural and civil engineers contribute towards the reduction of these negative impacts in a region where natural disasters like earthquakes, typhoons, tsunamis and landslides are prevalent? Structural and civil engineers have significantly contributed towards the protection and conservation of the natural environment especially when we consider the impact of natural disasters. on infrastructures and the environment. Civil and structural engineers, when they properly design structures and foundations for safety and stability, are actually contributing significantly to the preservation of the natural environment. Proper analysis, design and construction of structures will minimize damage or collapse. Refined modeling, testing and analysis of soil may prevent foundation failures. Strengthening and improvement of unstable slopes will control the occurrence of landslides. When structures are strengthened or retrofitted, the usable life of the structure is extended reducing end-of-life waste. These primary responsibilities of structural and civil engineers regarding safety and stability, in the end, leads to the reduction of non-renewable natural resources consumption and minimizing the accumulation of construction waste and disaster-caused debris waste. The responsibility of structural and civil engineers in designing for safety and stability and the role they play concerning the maintenance of environment especially in disaster-prone countries must be appreciated by everyone including the so-called “environmentalists.”

This article was published at the Philippine Star, Star Science Column, 6 March 2008

Understanding 2D Structural Analysis

In my computer laboratory class on "Structural Engineering Computer Methods", the students use Structural Analysis software like GRASP, ETABS and SAP2000. Learning to use the software is not the end itself but learning concepts on structural analysis is the primary objective of the course. To achive this objective, I wrote "Understanding 2D Structural Analysis" - an exploratory-type of instructional and learning material consisting of ten modules about modeling and analysis of framed structures in 2D using GRASP. Each module focuses on a specific issue on structural modeling and analysis which is discussed with the aid of graphical and tabular results obtained from GRASP. The set of learning modules is not a substitute to a textbook on structural analysis. The theory is not presented. No derivations or equations can be found. The student or reader must refer to the textbooks for definitions, equations and techniques. Each chapter begins with background information and a “case study”. The reader explores the issues raised in the case study through the “Things to Do” GRASP activities or by simply observing and analyzing the “Observation” and graphical and tabular results presented in the module. Included in the modules are “Things to Try” GRASP exercises and “Things to Ponder” comments on the analysis and design of structures. Using the set of learning modules, the reader or student with the aid of GRASP discovers important insights on the response and behavior of structures due to variations in the parameters of the model and configurations of the structure, changes in member and material properties, and also changes in the restraint and loading conditions. Through the graphical results, the student can visualize the phenomena and this would accelerate his understanding of concepts through the experience of seeing and interpreting solutions to various structural modeling and analysis problems. You may download this book from my website and use it in your class.

Structural Analysis Tips to Popsicle Stick Bridge Builders (Load Application)

Using a structural analysis software like Graphical Rapid Analysis of Structures Program (GRASP ) developed by the Asian Center for Computations and Software (ACECOMS) can help popsicle stick bridge builders in designing their bridges. The behaviour of bridges depends on how and where the loads will be applied. For example, if two concentrated loads will be applied to test a bridge with a truss design, applying the load as shown in the figure at the bottom or uppr part of the bridge will make a lot of a difference. The GRASP software was used to compare the maximum deflection at the bottom horizontal elements of the two bridges. The structures were analyzed as a "frame" since the joints may be assumed rigid because of the glued connections. The deflection for Bridge 1 where the loads were applied at the bottom is 20% higher than Bridge 2 where the loads are applied at the top. For Bridge 1, the bottom horizontal elements have large bending moments and axial forces and diagonal truss members carry large axial forces - the top horizontal members had minimal stresses. For Bridge 2, on the otherhand, the top horizontal elements may have large bending moments but the axial forces are not so large compared to bridge 1. The bottom horizontal elements now contributed more in resisting the loads by carrying more axial forces as compared to bridge 1. The diagonal truss elements of bridge 2 carry almost the same magnitude of axial forces. So before designing your bridges, know how and where the loads will be applied. It will make a lot of a difference in the bridge performance!

Structural Engineering for Kids 4 - Building Up London Bridge

London Bridge is a nursery rhyme where various concepts in structural engineering may be introduced. Obviously, the concept of structural engineering failures is described in this song - London Bridge is falling down. Structural failure this time is described in relation to different types of construction materials. The behavior and strength of various structural engineering materials and members can be described while playing the song - Build it up with pins and needles…Build it up with wood and clay…Build it up with iron and steel.. Build it up with stone so strong. How the structural members fail depends on the structural properties of the materials – brittle materials like concrete break or crush, ductile materials like iron and steel bend or yield. So London Bridge failed in various ways - Pins and needles bend and break…Wood and clay will wash away…Iron and steel will bend and bow… Stone so strong will last so long. Bridge failures, however, depend on many factors as shown in the video below like the structural design of the piers including the detailing of reinforcement, the bridge deck supports, the soil and foundation...

This nursery ryhme may also be a good opportunity to introduce the concept of strengthening and retrofitting of existing structures. So when London Bridge fell, the ryhme continues - We must build it up again, Up again, Up again. We should not wait for another bridge disaster to occur. We should learn form the previous bridge disasters like those that happened to the Tacoma Narrows Bridge in 1940 or the Hanshin Expressway in 1995. We should act now to strengthen and retrofit existing bridges and structures. The last slide in the video clip shows the bridge pier retrofitted against earthquake effects.

Structural Engineering for Kids 3 - The 3 Little Pigs and the Big Bad Wolf - Lessons on Wind Loads

Remember the story of the Three Little Pigs and the Big Bad Wolf? This is a story where kids will learn the importance of designing structures against external forces such as wind due to typhoons and hurricanes. The big bad wolf wants to eat the pigs. And to do that he must be able to destroy each pig’s house by blowing on the house. The big bad wolf represents external wind forces that a house must resist. So to protect themselves, the pigs have to build their own houses. Pig 1 built a house of hay. Pig 2 built a house of twigs, while Pig 3 built a house of stone. And you all know the story’s ending, the big bad wolf’s strong blowing power destroyed the houses of hay and twigs, but not the house of stone. Structural engineers must design structures against wind loads. Codes like the National Structural Code of the Philippines (NSCP) specifies wind zones with corresponding basic wind speeds in determining the design wind loads. For example, Metro Manila belongs to Zone II with a basic wind speed of 200 kph, while the Northeastern parts of Luzon and Visayas under Zone I have a speed of 250 kph. According to the Outdoor Advertiser's Association after the Typhoon Milenyo in 2006 struck Metro Manila, they designed their billboards for 120 kph (PDI Oct. 1, 2006) and this is less than 200 kph. The toppled billboards due to Typhoon Milenyo showed us what will happen to structures not designed, constructed and maintained properly against wind forces. Photo courtesy of Engr. Willy Lopez (DPWH): Fallen billboard due to Typhoon Milenyo 2007

Popsicle Stick Bridge Testing

Popsicle stick bridge building competitions usually choose the winner based on the strength/weight ratio. Usually loads are applied at the mid span of the bridge by placing incremental weights. The load at failure (P) is then determined and divided by the bridge weight (W) to get the bridge performance.

In the DLSU CES Bridge Building Competition, a Universal Testing Machine (UTM) is used to test the strength and displacement of popsicle stick bridges. Since the load will be applied on the bridge deck, an innovative method was devised so that it can be applied to truss bridges. Two 14 mm steel bars spaced at specified distance are placed on the bridge deck. A hollow steel cage is then placed on the two steel bars. The UTM is then applied on the steel cage which then transfers the load to the two steel bars and then to the bridge deck. A displacement transducer is attached to the UTM to measure the displacement (D) in mm. The load is applied and the value of P (kg) is obtained. The value of P can be predefined or when the load dial of the UTM stops which indicates bridge failure. The bridge rating, S = 1000(P/D)/W is then determined. The S rating represents the bridge stiffness (kg/m) per unit weight (kg). For example, the bridge shown in the video below was tested and it’s P = 30 kg, D = 25 mm and W = 1.50 kg. Hence, it’s rating , S = 1000(30/25)/1.50 = 800 (kg/m)/kg. By using the S rating, strength, displacement and weight become parameters in ranking the performance of the popsicle stick bridges.

Video Clip: Popsicle Bridge Testing using a UTM at DLSU CE Lab

Structural Engineering for Kids 2 - Shaping Up Humpty Dumpty

You may be wondering why Humpty Dumpty fell from the wall if he has legs and hands. Well this is because of his shape which is very unstable. When he sat on the wall, he is not anymore supported by his legs and a little push will make him roll and thus he fell from the wall. If Humpty Dumpty is an inverted triangle, he will be more unstable. He will stand on the tip of the triangle and he has to balance himself otherwise he'll fall. But a rectangular or upright triangle- shaped Humpty Dumpty will be difficult to be overturned even if he is not supported by his two legs since the bottom side is flat for both shapes and the center of mass is near the bottom.

Shapes play a major role in the behavior of structures. Observed that because of the stable upright triangular shape, the Pyramids of Egypt and the Eiffel Tower have remained structural wonders. In earthquake design of structures, rectangular and upright triangular shaped buildings and towers are more preferred because of their regular shape. To build tall skyscrapers like the Taipei 101, the floor area has to be reduced as it goes up. An inverted triangle is the worst type of configuration for a building because it will behave like an inverted pendulum where the inertia forces will be concentrated at the top and there is very little resistance to lateral movements. The overturning moment will be too large such that it can easily be toppled down. Irregularly shaped structures, of course, can still be built provided they are properly modelled, analyzed and designed.

Structural Engineering for Kids 1- Humpty Dumpty & Structural Failures

Remember the nursery rhymes and songs your parents have read and sung for you just to put you to sleep? You or your parents may have not realized that when you were babies, you were unconsciously introduced to basic concepts of Structural Engineering whenever these nursery songs are played.

Humpty Dumpty sat on a wall

Humpty Dumpty had a great fall

All the king’s horses and

All the king’s men

Couldn’t put Humpty Dumpty

Together again

This nursery rhyme is a favorite of my two kids. It is a lesson on structural engineering failures and instability. The egg-shaped Humpty Dumpty is an example of an unstable structure. A little push will make it roll and fall. Similarly, buildings or bridges will be damaged or will collapse if they are not properly designed and built against expected forces. Proper design of foundations, detailed analysis of connections, and correct design of structural members are necessary ingredients against structural failures. Minor damages such as simple cracks may be acceptable but structures must not collapse, such that they are beyond repair endangering people's lives.

Inspired by the Humpty Dumpty music, I created a short video clip about the damaged buildings during the 1990 Luzon Earthquake. Humpty Dumpty here represents Luzon and its damaged structures. Perhaps, nursery rhymes and children songs may be a good way of introducing Disaster Awareness and Preparedness to kids.

The idea of this blog was inspired from Henry Petroski’s book, “To Engineer is Human.” Petroski argues that “the ideas of engineering are in our bones and part of our human nature and experience.” This is a good book specially for non-technical people who wants to understand concepts of engineering design.

Understanding Eathquakes& Disasters:Photo-Video

Computers and multimedia equipment have become popular tools in public presentations. In most conferences or seminars, a multimedia projector has become a common equipment. Recognizing this fact, the use of multimedia may be used for effective public awareness and education. However, there is a lack of multimedia software or presentations that are readily available for public use. It is for this reason, that I pursued the creation of photo-video presentations to be used in schools and public lectures. The photo-video presentations consists of photos or images integrated with text and music by a video editing software. The techniques and tools needed in producing personal multimedia presentations are discussed in a paper in my website: http://mysite.dlsu.edu.ph/faculty/oretaa.

“Understanding Earthquakes and Disasters: Photo-Video Presentations” is a project funded by the DLSU-Manila University Research Coordination Office (URCO). It consists of eight short presentations (watch the video clip below to know the 8 photo-video presentations) which can be played using a DVD player or a computer with Windows Media Player or similar software. The main focus of the photo-video presentations is the impact of earthquake hazards – ground shaking, surface rupture, liquefaction, tsunami, landslides – to the community and infrastructures. By presenting the effects of earthquakes, the public will understand their vulnerability to the different types of seismic hazards. And by knowing ones’ vulnerability, appropriate actions can be done to mitigate the adverse impacts of the hazards and avoid a disaster. Contact me if you want a copy of the presentation.

Introducing the 8 Titles in "Undertanding Earthquakes & Disasters: Photo-Video Presentations"

Building Popsicle Stick Bridges

I built my first popsicle stick bridge about 12 years ago when I was introduced to the bridge building contest organized by the students of the DLSU Civil Engineering Society (CES). My bridge was a through truss bridge. A through truss bridge derives its strength from the arrangement and strength of the truss elements. The load is transferred from the bridge deck to the truss elements and then to the supports. There are other types of bridge forms that can be created. A deck or girder bridge resists loads through bending – hence you must design the bridge deck such that it will have a large moment of inertia.The arch bridge, on the other hand, transfers the load to the abutments or supports through compression.

Bridge building is a fun and challenging activity. By applying basic strength of materials and bridge design principles, a little creativity and a lot of patience, you can create your own masterpiece similar to the CES bridges shown. So why not test your skills on popsicle stick bridge building by joining the 5th DLSU CES Bridge Building Competition? The competition is open to all civil engineering students in the Philippines. The best bridge design wins P5,000. The bridge with the largest “stiffness/weight ratio” wins P10,000. Check-out the rules in the ads shown in this blog site.

There are more postings related to popsicle stick bridge building and bridges in this blog. Go to this link.

Get some building tips at

http://claymore.engineer.gvsu.edu/~oostdykj/techniques.html.

Check-out http://pghbridges.com/basics.htm for various forms.

Photos of CES Bridges by Joenel Galupino: http://misfortunes.multiply.com/photos/album/60/MISFORTUNE_55