Seismic Forces on Non-Structural Members

Seismic Forces on Non-Structural Members (EuroCode 8 & ASCE 7-16)

Introduction

ProtaStructure calculates non-structural member forces according to EC8 Chapter 4.3.5.

In the current document, calculations details about non-structural members earthquake force and parameters such as seismic coefficient are explained.

Building Model Details

The example building model consists of 7 regular floors. 3D and typical story plan view are shown below.
Notes
Ensure that Building Analysis is successfully completed.  Check and verify the analysis results is correct using procedures in this article :  Building a Model Guideline

User Interface

1.  Go to Loading tab > Select Non-Structural Component Loads. 
  1. The Non Structural Member Force Calculator will be launched. 


2.  Click "Add Member" to add member 
3.  Member label, Non-structural member type according to EC8 Table 4.4, Weight , Elevation from the base must be set by the user. 
  1. The other parameters such as seismic coefficient and member forces are calculated according to EC8 Chapter 4.3.5
Seismic Coefficient

According to EC8 4.3.5.2 (2) seismic coefficient, Sa is defined as, “Seismic coefficient applicable to non-structural elements”. Calculation details are given in subclause 4.3.5.2 (3) which states the formula (4.25)  given below. 


α          : Ratio of the design ground acceleration on type A ground, αg, to the acceleration of gravity g

S          : Soil factor

Ta           : Fundamental vibration period of the non-structural element

T1           : Fundamental vibration period of the building in the relevant direction

z          : Height of the non-structural element above the level of application of the seismic
   action (foundation or top of a rigid basement)

H         : Building height measured from the foundation or the top of a rigid basement




Seismic Force

According to EC8 4.3.5.2 (2) horizontal seismic force, Fa, is defined as,” the horizontal seismic force, acting at the center of mass of the non-structural element in the most unfavorable direction”. Calculation details are given in subclause 4.3.5.2 (3) which states the formula (4.24)  given below.

 

Sa        : Seismic coefficient applicable to non-structural members

Wa          : Weight of the non-structural member

qa         : Behavior factor of the non-structural member

γa         : Importance factor for the member, according to EC8. 4.3.5.3


Summary

In this article, calculation details of seismic forces acting on the non-structural elements according to EC8. Clause 4.3.5 is explained. Results of the “Non-Structural Member Force Calculator” macro are verified with hand calculations. 

Additionally, ProtaStructure can calculate Seismic Forces on Non-Structural Members according to (ASCE 7 - 16). User ınterface and calculation details are given as attached.