Fundamental period of the structure with user values
Certain seismic codes allow two ways of calculating the value of the Fundamental period of the structure (used to analyse the base shear). The codes implemented into CYPECAD that allow this option are:
- CFE 2008 (Mexico)
Manual de Diseño de Obras Civiles. Diseño por Sismo. - COVENIN 17561:2001 (Venezuela)
Norma Venezolana COVENIN 1756-1:2001. Edificaciones sismorresistentes. - NC 46:1999 (Cuba)
Construcciones sismo resistentes. Requisitos básicos para el diseño y construcción. - NEC 11 (Ecuador)
Norma Ecuatoriana de la Construcción. Capítulo 2.- Peligro sísmico y requisitos de diseño. - Norma Técnica E.030 (Peru)
Norma Técnica E.030 Diseño Sismorresistente. - NSR-10 (Colombia)
Reglamento Colombiano de Construcción Sismo Resistente (2010). - NTC 2004 (México)
Normas Técnicas Complementarias para Diseño por Sismo.
With these codes, the value of the fundamental period of the structure can be indicated in CYPECAD in the following two ways:
- Based on the code
- User-defined
Either of the two options can be selected in the Estimation of the fundamental period of the structure in the Code for the calculation of seismic loading window (Project menu > General data > select the “With seismic loading” option in the “Loads” section > select one of the aforementioned codes).
The value of the fundamental period of a building must be obtained from the properties of its seismic resistance system, in the direction being considered, following the principles of structural dynamics. Alternatively, the majority of seismic codes allow the use of other procedures to estimate the fundamental period:
- In accordance with empirical formulas provided in its articles.
- In accordance with other methods, as long as these are adequately supported, either analytically or experimentally.
The estimated fundamental period is applied in the analysis of the static shear at the base of the building (baseline shear) to adjust the dynamic results to the minimum prescribed design code values in the case of applying the dynamic method and to generate the equivalent static lateral forces if the static method is applied.
The values indicated by the codes are limits that can be used when lacking other more accurate data. If users have fundamental period values that are more suitable for their structure (calculated by standard methods or by software tools such as CYPECAD that analyse the fundamental period of the structure in each direction - its values can be consulted after the analysis in the “Justification of seismic action” report: Files menu > Print Job data report) they can specify them by selecting the User specified factors option located in the Code for the calculation of seismic loading window.
User-specified seismic spectrum
For certain seismic codes included in CYPECAD, the program allows users to specify a personalised seismic spectrum different to the one specified in the code.
A design spectrum must be defined to perform a seismic analysis of the structure. Each earthquake-resistance code provides the criteria to be followed within a certain territory to consider seismic action in the project. Nonetheless, CYPECAD and CYPE 3D allow designers to adopt criteria different to that established in the code at their own risk. For certain earthquake codes, both programs offer two procedures for defining the spectrum that will be used to carry out the seismic analysis of the structure. The design seismic spectrum can be:
- Calculated as specified in the applicable seismic code.
- User-specified based on their own considerations.
The seismic codes that CYPECAD and CYPE 3D currently allow personalised spectrums to be designed for are:
- NCh433.Of1996 Mod.2009 (Dºnº61. de 2011) (Chile)
Norma Chilena Oficial Diseño Sísmico de Edificios (Incluye modificaciones del decreto nº 61 (V. y U.) de 2011). - NEC-SE-DS 2014 (Ecuador)
Norma Ecuatoriana de la Construcción. Peligro sísmico. Diseño sismo resistente. - NEC -11 (Ecuador)
Norma Ecuatoriana de la Construcción. Capítulo 2.- Peligro sísmico y requisitos de diseño. - Norma Técnica E.030 (Peru)
Norma Técnica E.030 Diseño Sismorresistente. - NSR - 10 (Colombia)
Reglamento Colombiano de Construcción Sismo Resistente (2010)
This possibility for more seismic codes will be implemented in upcoming versions.
Codes included in the user license
Depending on the country from which the licensee has acquired the license, each program will only activate the implemented design codes corresponding to that country. More information about this aspect and the possibility of acquiring additional codes is available under Programs and codes included in the user license.
CYPECAD versions
CYPECAD is available in its unlimited version and also in two limited versions called LT30 and LT50, which contain the same tools and module acquisition possibilities, but have the following conditions:
CYPECAD LT50:
- Fifty columns
- Four floor groups (Floor group: floors which are the same and consecutive)
- Total of five floors
- Walls: one hundred linear metres
CYPECAD LT30:
- Thirty columns
- Four floor groups (Floor group: floors which are the same and consecutive)
- Total of five floors
- Walls: one hundred linear metres
Integrated 3D structures of CYPECAD (also LT50 and LT30) is not technically a module. To define these 3D structures in CYPECAD, users must also have the required permits to use CYPE 3D in their user license and, optionally, modules that are exclusive to CYPE 3D.
