Contoh Perhitungan Nilai Umum K Batang Tekan Struktur Baja | Lightboard

Summary

This video tutorial explains how to calculate the general stiffness value (k) for two types of columns in a building structure, using specific formulas and charts. The process includes calculating stiffness ratios (G) at various points of the columns, considering structural types (rigid vs. non-rigid). It then explains how to use these values with appropriate charts to determine the final stiffness values (k). The video emphasizes understanding column orientations, the role of beam stiffness, and how structural behavior under lateral loads affects the overall calculation. The tutorial is designed for engineering students or professionals in structural analysis.

Takeaways

• 😀 The value of 'k' is determined by the stiffness ratio between the column and beam, considering whether the structure is rigid or flexible.
• 😀 For rigid structures, use the left-side chart to calculate 'k', while for flexible structures, use the right-side chart.
• 😀 A rigid structure doesn't experience significant lateral deformation, while a flexible structure undergoes noticeable lateral deformation.
• 😀 In the example, the calculation for 'k' will be performed for two columns: one in the middle of the second floor and another on the first floor's left side.
• 😀 The column at point 'Hae' (on the second floor) has a moment of inertia 'Ia' of 10800, and the beam has a moment of inertia 'Ix' of 7210.
• 😀 The value of 'k' at point 'Hae' was calculated to be approximately 1.86 using a stiffness ratio derived from the column and beam's properties.
• 😀 The value of 'k' at point 'Dea' (on the first floor) was calculated to be around 2.1 after considering the column's and beam's stiffness and moments of inertia.
• 😀 For column 'Hae', the moment of inertia of the beam was divided by the beam's length to get the stiffness value, leading to the final calculation of 'k'.
• 😀 In case the points of calculation are swapped, the result for 'k' would remain the same, showcasing the consistency of the method.
• 😀 The value of 'k' for a structure with lateral movement (flexible) is usually greater than 1, while for rigid structures, it ranges between 0.5 and 1.

Q & A

What does the 'k' factor represent in the context of this video?

The 'k' factor represents the general stiffness factor for columns in structural analysis. It is a function of the stiffness ratios (Ge and GB), where Ge is the ratio of column stiffness to beam stiffness, and GB is the ratio of beam stiffness to column stiffness.

What is the difference between a 'goyang' structure and a 'tak bergoyang' structure?

A 'goyang' structure is one that experiences significant lateral deformations under load, while a 'tak bergoyang' structure is one where lateral deformations are negligible, typically due to the presence of bracing elements.

How is the stiffness ratio Ge determined?

The stiffness ratio Ge is determined by comparing the stiffness of the column to that of the beam. Specifically, it is the ratio of the moment of inertia of the column (Ia) to the moment of inertia of the beam (Ix or Iy), divided by the length of the beam.

What are the steps involved in calculating the 'k' factor for a column?

The steps include: 1) Calculating the stiffness ratios (Ge and GB) for the column and beam at their respective points, 2) Using the appropriate charts for structures that are either 'goyang' or 'tak bergoyang', and 3) Determining the 'k' factor from the chart based on the calculated stiffness ratios.

What does the notation 'Ia' and 'Ix' represent in this video?

'Ia' refers to the moment of inertia of the column about its axis, while 'Ix' refers to the moment of inertia of the beam about its bending axis.

Why are the column orientations important in calculating 'k'?

The orientation of the column affects how it will deform under load, which influences its stiffness. Different orientations result in different moments of inertia (Iy vs. Ix), which are crucial for calculating the correct stiffness ratios.

What does the term 'momen inersia' mean?

Momen inersia refers to the moment of inertia, a property that quantifies the resistance of a structural element (like a column or beam) to bending. It plays a key role in determining stiffness and load distribution.

What is the significance of using different values for 'k' depending on whether the structure is 'goyang' or 'tak bergoyang'?

For 'goyang' structures, the value of 'k' is generally greater than 1 due to the significant lateral deformations, while for 'tak bergoyang' structures, the value of 'k' is typically between 0.5 and 1, reflecting minimal lateral deformation.

What are the implications of using a 'jepit' (fixed) support condition in structural analysis?

For a 'jepit' (fixed) support condition, the column is treated as having zero rotation at the support, which simplifies calculations. The stiffness factor for a column with a fixed support is taken as 1.0, as specified in the regulations.

How are the values of 'G' used in the calculation of 'k'?

The values of 'G' represent the stiffness ratios at the upper and lower points of the column. These values are then used with the appropriate charts to determine the stiffness factor 'k'.