On Monday February 22 was presented at the "In Kiu" which masterfully directed Atahualpa and Sergio García Ramírez Hernández through Tele Media Channel 25 Dominicanos SA a new evaluation system dynamic behavior existing buildings in the event of an earthquake of certain intensity. This system is promoted nationally by the company Lexco in the person of its President Mr. Jorge Lopez and Engineering Director of Engineering (PhD), Erick Hernandez, who have representation for the Cibao area with the engineer Antonio Rodríguez.
From the point of view of a construction project there are several reasons why the structure does not behave in a manner appropriate to a given seismic intensity, which we quote below:
Poor structural design:
If a structure does not adequately provide the moment of conception the types of efforts that can occur throughout life and are not included in their plans the most advanced structural engineering concepts exist, often expressed in legislation such as the ACI among many others, there greater risk that the structure is seismically vulnerable.
Bad Execution:
As stated "The structures do not behave as calculated, but as it built a "bad building practice or a deficiency in the quality of the materials ruins all intellectual and scientific efforts aimed at the design of seismically resistant structures.
deterioration Action:
As the engineer Antonio Rodriguez, a structure may have been well conceived and well executed then according to the best construction practices comply with the specifications drawings from the structural standpoint, but have deteriorated due environmental chemical exposure.
According to him, is well known, for example, that a reinforced concrete structure built next the sea is vulnerable to attack by chloride and sulfate occasions to present in some soils or groundwater. In this case, the criteria should prevail even over the durability of resistance, which means that if the product of a concrete mix design with durability features specified for the environment, resulting in a compressive strength greater than required by structural calculations should assume the latter.
Clearly, a change in the compressive strength of concrete for this reason requires a revision of structuralism to prevent further changes to the project from degenerating into a brittle failure mode, all of which can be exploited by others to obtain thinner sections, so that greater physical space, less volume of concrete, greater uptime and lower cost long-term compensation for being attacked by sulfates with consequent corrosion of reinforcing steel which in turn results in thickening of the oxidation product, prompting not only the detachment of the concrete or mortar that covers it, but the reduction of the efficiency of this material in the tensile strength, leading her eventually collapse even without the occurrence of a major seismic event.
Unfortunately, in this last aspect, la durabilidad, la ingeniería está aún muy en ciernes y todavía es difícil estimar con cierta precisión el tiempo de vida útil de la estructura y las necesidades de mantenimiento que a lo largo de la misma serán necesarios implementar. Lo cual facilitaría a los financieros y economistas una correcta evaluación económica a lo largo del tiempo de servicio de estas construcciones y más aún, tomar ciertas decisiones en el mismo momento en que se concibe el proyecto.
Conceptos Antisísmicos Superados:
En la medida en que avanza el tiempo, nuevos sismos van ocurriendo alrededor del mundo, cada evento de ese tipo se aprovecha para estudiar su comportamiento y its effects, this translates into a better understanding of how they interact with structures. From this follows that if a construction project has been well conceived at the time and still is built strictly according to these criteria, the structure is not adequate to deal with an earthquake in the light of the latest knowledge on the subject. Even when the structure is not significantly degraded by the passage of time.
Because of all the above is that the company has decided to introduce Lexco the Dominican market this ingenious drainage system that consists of three levels. To Know:
1 -) Basic Evaluation: Evaluation earthquake resistant based on information in plans, soil studies and non-destructive inspection of the structure to determine the quality of building materials. This review is whether the building meets the minimum requirements established earthquake resistant by the International Building Code and the American Society of Civil Engineers.
The major disadvantage of leaving the research to this level is that necessarily must begin with a set of premises that are not always necessarily true, that is why, when the output generated to this point is dubious or worse, reflects a clear risk of collapse or severe damage to the structure in the event of a earthquake of certain intensity, it is recommended to continue to the next levels of evaluation.
2 -) Evaluation instruments: Instrumentation with accelerometers in various parts of the building to determine dynamic properties (vibration modes and frequencies) of these areas of the structure in its actual state, love of what is stated in the plans. Is the equivalent of putting on a "stethoscope" to the structure to see beyond appearances and determine its structural condition.
As stated, the devices are placed at strategic points that the expert has determined to be the most convenient, thereby establishing the relationship between the vibration that occurs in the pre-selected points and the results measured by another device placed at the base of the building where there is no amplification effect due to the height where it is located .
At this point, not only does the collection of information coming from the accelerometers but also of being combined with information from the studies are made flat concrete strength and materials as part of the structure existing with modern equipment and mechanisms that allow us to evaluate the quality, strength of concrete and reinforcing steel available in situ.
Worth mentioning that these accelerometers are capable of generating displacements thousand readings per second.
3 -) Evaluation of Advanced Instrumentation and Seismic Risk: Assessment
earthquake-resistant based on specific earthquakes are measured in parts of the planet with conditions similar to those of the locality where the building in the Dominican Republic and determination of levels expected damage to different intensities of the same.
After these reviews Lexco offer the customer a detailed report with the structural health of buildings, seismic vulnerability and recommendations for strengthening the structure in case should this prove necessary.
is important to note, as Erick Hernandez narrows, that no method of evaluation may require one hundred percent damage to a particular structure will suffer in the event of an earthquake, among other things because there are many characteristics to be assessed each event of this type (duration, intensity, frequency, direction) that given the myriad possible combinations of these and other forces the analysis is kept within the range of probabilities.
is a pity that there is no honorable exceptions to this in the Dominican Republic culture testing after construction completed, not only in the sense of preparing As Built drawings but to ensure that the behavior meets the provisions in the design, as with certain devices such as aircraft, which by its nature and importance are tested again and After rigorous procedures after manufactured by the catastrophic failure that would result in them.
Clearly, the obvious question. Why do not our civil works if we have the tools knowledge and experience for this?
We bet that the earthquakes we've seen in recent months and the permanent threat that lies over the Dominican Republic is trend and level of awareness will change for the better. Amadeo
Alcántara
From the point of view of a construction project there are several reasons why the structure does not behave in a manner appropriate to a given seismic intensity, which we quote below:
Poor structural design:
If a structure does not adequately provide the moment of conception the types of efforts that can occur throughout life and are not included in their plans the most advanced structural engineering concepts exist, often expressed in legislation such as the ACI among many others, there greater risk that the structure is seismically vulnerable.
Bad Execution:
As stated "The structures do not behave as calculated, but as it built a "bad building practice or a deficiency in the quality of the materials ruins all intellectual and scientific efforts aimed at the design of seismically resistant structures.
deterioration Action:
As the engineer Antonio Rodriguez, a structure may have been well conceived and well executed then according to the best construction practices comply with the specifications drawings from the structural standpoint, but have deteriorated due environmental chemical exposure.
According to him, is well known, for example, that a reinforced concrete structure built next the sea is vulnerable to attack by chloride and sulfate occasions to present in some soils or groundwater. In this case, the criteria should prevail even over the durability of resistance, which means that if the product of a concrete mix design with durability features specified for the environment, resulting in a compressive strength greater than required by structural calculations should assume the latter.
Clearly, a change in the compressive strength of concrete for this reason requires a revision of structuralism to prevent further changes to the project from degenerating into a brittle failure mode, all of which can be exploited by others to obtain thinner sections, so that greater physical space, less volume of concrete, greater uptime and lower cost long-term compensation for being attacked by sulfates with consequent corrosion of reinforcing steel which in turn results in thickening of the oxidation product, prompting not only the detachment of the concrete or mortar that covers it, but the reduction of the efficiency of this material in the tensile strength, leading her eventually collapse even without the occurrence of a major seismic event.
Unfortunately, in this last aspect, la durabilidad, la ingeniería está aún muy en ciernes y todavía es difícil estimar con cierta precisión el tiempo de vida útil de la estructura y las necesidades de mantenimiento que a lo largo de la misma serán necesarios implementar. Lo cual facilitaría a los financieros y economistas una correcta evaluación económica a lo largo del tiempo de servicio de estas construcciones y más aún, tomar ciertas decisiones en el mismo momento en que se concibe el proyecto.
Conceptos Antisísmicos Superados: En la medida en que avanza el tiempo, nuevos sismos van ocurriendo alrededor del mundo, cada evento de ese tipo se aprovecha para estudiar su comportamiento y its effects, this translates into a better understanding of how they interact with structures. From this follows that if a construction project has been well conceived at the time and still is built strictly according to these criteria, the structure is not adequate to deal with an earthquake in the light of the latest knowledge on the subject. Even when the structure is not significantly degraded by the passage of time.
Because of all the above is that the company has decided to introduce Lexco the Dominican market this ingenious drainage system that consists of three levels. To Know:
1 -) Basic Evaluation: Evaluation earthquake resistant based on information in plans, soil studies and non-destructive inspection of the structure to determine the quality of building materials. This review is whether the building meets the minimum requirements established earthquake resistant by the International Building Code and the American Society of Civil Engineers.
The major disadvantage of leaving the research to this level is that necessarily must begin with a set of premises that are not always necessarily true, that is why, when the output generated to this point is dubious or worse, reflects a clear risk of collapse or severe damage to the structure in the event of a earthquake of certain intensity, it is recommended to continue to the next levels of evaluation.
2 -) Evaluation instruments: Instrumentation with accelerometers in various parts of the building to determine dynamic properties (vibration modes and frequencies) of these areas of the structure in its actual state, love of what is stated in the plans. Is the equivalent of putting on a "stethoscope" to the structure to see beyond appearances and determine its structural condition.
As stated, the devices are placed at strategic points that the expert has determined to be the most convenient, thereby establishing the relationship between the vibration that occurs in the pre-selected points and the results measured by another device placed at the base of the building where there is no amplification effect due to the height where it is located .
At this point, not only does the collection of information coming from the accelerometers but also of being combined with information from the studies are made flat concrete strength and materials as part of the structure existing with modern equipment and mechanisms that allow us to evaluate the quality, strength of concrete and reinforcing steel available in situ.
Worth mentioning that these accelerometers are capable of generating displacements thousand readings per second.
3 -) Evaluation of Advanced Instrumentation and Seismic Risk: Assessment
earthquake-resistant based on specific earthquakes are measured in parts of the planet with conditions similar to those of the locality where the building in the Dominican Republic and determination of levels expected damage to different intensities of the same.
After these reviews Lexco offer the customer a detailed report with the structural health of buildings, seismic vulnerability and recommendations for strengthening the structure in case should this prove necessary.
is important to note, as Erick Hernandez narrows, that no method of evaluation may require one hundred percent damage to a particular structure will suffer in the event of an earthquake, among other things because there are many characteristics to be assessed each event of this type (duration, intensity, frequency, direction) that given the myriad possible combinations of these and other forces the analysis is kept within the range of probabilities.
is a pity that there is no honorable exceptions to this in the Dominican Republic culture testing after construction completed, not only in the sense of preparing As Built drawings but to ensure that the behavior meets the provisions in the design, as with certain devices such as aircraft, which by its nature and importance are tested again and After rigorous procedures after manufactured by the catastrophic failure that would result in them.
Clearly, the obvious question. Why do not our civil works if we have the tools knowledge and experience for this?
We bet that the earthquakes we've seen in recent months and the permanent threat that lies over the Dominican Republic is trend and level of awareness will change for the better. Amadeo
Alcántara
