Abstracts Presentados en la Mesa de Trabajo - 20 Noviembre

1) Identification of structural damage in buildings to avoid fatalities
Dr. Ramsés Rodríguez Rocha - ESIA Zacatenco

Buildings might be subjected to external forces such as the ones from earthquakes, hurricanes among others. These could affect the structural integrity therefore, in the worst case, the collapse of the system and loss of human lives. The main objective of this project is to identify structural damage in buildings to avoid fatalities.

2) DYNAMIC EFFECTS ON LATTICED STRUCTURAL SYSTEMS
Dr. Alejandro Martínez-Márquez - ESIA Tecamachalco

Slender and nice appearing, latticed structures (polyhedral, as an instance) are –needless to say- subject to the action of wind and earthquake dynamic effects. Noticeably, although not usually taken into account, in spite of their low weight, dynamical seismic effects show signals of the need to their being taken into account. Quite naturally, as it occurs in any trussed frame, wind effects might become the most relevant issue when dealing with loading systems.

In fact, any analysis program commercially available is able to include the horizontal force equivalency of seismic action, while neglecting additional effects due to: i). turbulence; ii). flutter; and, to say the least, iii). resonance between wind dynamics and prevalent natural vibration periods of the structure, due to its members light weight, tend to become relevant. For certain shape geometry and the nature of behavioral materials employed in building the framework, vibration effects might very well reach system forces hard to imagine and well above those derived from the usual static loading assumption.

The low weight of the whole structure leads to assume that no seismic effect is to affect the behavior of the structural system. Nonetheless, few computational and much limited laboratory experiences seem to reflect the fact that higher modes of vibration are bound to produce localized resonance effects among interacting bars within the system, usually made up of slender bars receiving the load coming in from the shielding subsystem. So much so that dynamic instability might be prompted

Departing from results previously derived, namely the computer program ANESTES II (as developed by the present author), so far it has been possible to integrate a new program module to deal with some of the dynamical effects, in addition to the static loading systems. There are no final conclusions to report by the time being. However, if required, it shall be possible to display a limited number of results obtained for statically acting forces, intended to represent some dynamical effects without their being formally incorporated.

3) The lack of use of the Sustainable architecture in the campuses of the IPN, a case study
M. en Arq. Ezequiel Colmenero Búzali - ESIA Tecamachalco

To talk about Sustainable Architecture we need to understand what this concept means to us in our modern context. Sustainable means that something can be maintained by itself and architecture is the art and technique of design and build buildings.

If we think in Sustainable Architecture we have to think too in the origins of this concept, wich are in que Sustainable Development, an idea best explained in the “Brutland Report” of the World Comission of Enviroment and Development at 1987.

To an architect, the way to deal with the Sustainable Architecture is by the usage of the Bioclimatic Design, which uses the ecological perspective of the places and applies observations of the enviroment to the building design.

In this research I made an observation and analysis o fan specific building, the “Edificio 5 del anexo” located in the Unidad Profesional Zacatenco of the Instituto Politécnico Nacional in Mexico City. The building is a modification to an original proyect in order to expand the work area. This building was not planned around the climatic characteristics of the place, it gets very warm inside almost when is not so hot outsider, is bad positioned and the air ventilation needs to be done by air conditioners making a bad use of energy and even the building have constant modifications made by its users in order to create a better place to work.

After a complete analysis of the building, I give some proposal Solutions and alternatives for future building proyects of this kind. Those proposals are given with the characteristics of the current building trying to correct the mistakes in its design.This research is intended to create conscience in our institution about the Bioclimatic Design and the importance of using our own human and proffesional resources to our areas of work and installations. Almost we need to get in a common agree with authorities to have these bioclimatic notions in the Mexican law in order to have a better world and save our natural resources.

4) MECHANICAL BEHAVIOR OF THE PIPELINES UNDER COMBINED LOADS
Dr. Héctor Sánchez Sánchez - ESIA Zacatenco

The growing need of infrastructure to satisfy the national oil industry demand require the evaluation and retrofit of existing pipelines, furthermore to build new pipelines for transportation and distribution of oil products.

The current development of structures and offshore structures requires more sophisticated designs of the pipelines and risers capable to assuring an optimal level of security. It is a common situation, in the performance of the buried pipelines or fixed offshore platforms, in which pipes might be found with different actions during their life time. This condition could represent an unfavorable situation that might become highly critical given the conditions they are found in.

In the high risk zones in Mexico have been observed that the ground motions often show large horizontal displacements. Those displacements cause large deformations of buried pipelines. Then, the knowledge of study and design recommendations related to deformability of the pipes has not been sufficiently provided. A grand number of studies have been reported concerned about the plastic deformations or buckling of the straight pipe. Most of them are performance of column pipe without internal pressure. Therefore, the purpose of this study is clarifying the deformations; steel pipes with internal pressure, axial compression and bending are analyzed.

The mechanical behavior such as, stresses and deformability of the welded steel pipes is investigated under different combined loads. Stress linear and non- linear analysis using FEM is performed in order to simulate the large deformations of the pipes.
Consequently, this research has focused on the behavior and study under seismic conditions, of already existing pipelines, located in high risk zones. The seismic actions induced a flexion pattern, causing deformations, strain, curvatures and ovalization along of the pipelines. This research describes in-plane bending the behavior in closing and opening mode to evaluate the response of the pipelines. The study involved a typical 20” internal diameter, API 5L X52 steel pipeline.

5) Development of new numerical applications for resolution of linear and non-linear problems of structural engineering based on Finite Element Method
Dr. Norberto Domínguez Ramírez - ESIA Zacatenco

One of the most important lines of research in civil engineering is the modeling of structural systems in order to know and predict their realistic behavior as they are subjected to different combination of loads and environments. By simplicity, elastic behavior has been adopted to represent the response of different materials used in civil engineering as concrete, steel, wood, etc. This assumption facilitates numerical analysis and correspond very well to reality if two main hypothesis are respected: a)materials do not reach their corresponding elastic yield point and b) any deformation is very small and disappears as soon as the load is retired from the structure.

However, a lot of structures may develop in one of their components any kind of non-linear response due to inelastic material behavior and/or geometrical non linear behavior. For this reason, it is important to develop mathematical models which reproduce in a better way any non linear response observed in structures.

In this research, we focus in three major things:
1) development of non linear models for material behavior (particularly, for reinforced concrete, bonding, and steel) based in thermodynamic theory,
2) construction and development of Finite Elements (new or modified),
3) application of last two items in conventional and non conventional civil structures.

A lot of computational work is necessary for completing our objectives. Basically, for development we have adopted two important FEM codes: FEAP, which is an academic/research code developed by Prof. R.L. Taylor from University of Berkeley, and Code_Aster, a professional code developed by Electricité de France, which is used widely for modeling of nuclear central plants in France.

International collaboration is preponderant for our project. We collaborate with:
Prof. Adnan Ibrahimbegovic, LMT ENS-Cachan, France
Dr. Shahrokh Ghavamian, Numerical and Engineering Consulting Services (NECS), France