MAIN STEEL FRAME

from The Pinnacles - OIC 2022

STRUCTURAL CONCEPT

Outer Frame Structural Design

Wind Load

Windiest month of the year in Osaka is February, with an average hourly wind speed of 4.2 m/s.

Analysis of wind load using analytical procedure. In our case, the structure does not satisfy the conditions for using the simplified procedure. Therefore, the wind load is calculated using the analytical procedure as it is a regular shaped structure, and it does not have response characteristics making it subject to across-wind loading, vortex shedding, instability due to galloping or flutter, or does not have a site location that require special consideration. The steps of analytical procedure are described in ASCE 7 Section 6.5.3.

Design Code:

AIJ Recommendations for Loads on Buildings, Architectural Institute of Japan, 1996

Part 2: Wind actions BSLJ (2000), Building Standard Law of Japan

ASCE Standard, ANSI/ASCE 7-95, 1996

Seismic Design

1. Bracings

Bracing in vertical planes (between rows of columns) creates load channels for lateral stability and for transferring horizontal forces to the ground. Cross bracing is used to keep structures stable during seismic occurrences like earthquakes as well as when the wind blows. Additionally, it restricts lateral movement of the building, lessening the risk of cladding and component damage. Cross bracing typically consists of diagonal elements positioned in an X-shape in a vertical plane and is made from steel rods, angles, or tubes. Normally, cross bracing is situated parallel to a building's columns.

Earthquake Load

Osaka, Japan is in high seismicity region. On June 18, 2018, an inland crustal earthquake measuring MJMA 6.1 struck Japan's Osaka basin. The highest PGA for this event was greater than 0.9 g, and it was followed by several lesser aftershocks.

Response spectrum method is used to examine the elastic and inelastic response behaviour of the structure.

Friction Dampers function as a reusable fuse that simultaneously releases energy. No replacement is required after an earthquake event. Therefore, the building can endure an earthquake without suffering serious structural damage.

By creating friction through a spinning friction joint, a rotational friction damper decreases seismic energy. They dissipate the input energy of earthquakes through friction in their rotating plates.

Details Of Steel Frame Structure

Steel Section Size

Foundation Of The Structure

Note: All dimension in mm

Foundation Element

● 3 piles group is selected as the foundation element for the structure.

● The dimension of pile is 200mm x 200mm.

● Each pile has working load value of 450kN. However, 80% of the working load is used as the pile bearing capacity (0.8 x 450kN = 360kN).

● the soil bearing capacity is assumed as 200 kN/m3

Note: All dimension in cm

Details Of Steel Frame Structure

Base Plate

Elevation

Loads from steel columns are transferred through a steel base plate to large area of the pile cap. The base plate are welded directly to the columns. The base plate is larger than the column size to provide room for the placement of the anchor bolt holes outside of the column.

Other Components

1. Hoisting system

● Electric Chain Hoist

Our hoisting system uses a 2 tonne electric chain hoist with remote control since our tensile membrane needs machinery to move vertically. The analysis of loads is shown below.

Dead load carried by each machine:

Self weight of tensile membrane

Total weight of tensile membrane = 13.387kN / 9 cables = 1.5 kN ≈ 2.0 kN

Weight of rainwater = 11.25kN

Total dead load = 13.25kN (less than 2 tonnes)

2. Wire Ropes for Tensile Structure

● Cable to Machine Connection

This type of connection is used to connect the hoist machine to the cable by creating a hook to carry the machine. Bolt grade 8.8 is used to overcome high tensile and shear stress.

A 19 strands rotation-resistant rope is adopted in the cable system of our tensile membrane. A core strand is surrounded by six strands in one direction, and 12 strands are then arranged around this initial operation in the reverse way. This kind of rope provides greater crushing resistance, a higher strength-to-diameter, resistance to bending fatigue, and outstanding stability because of its tightly compacted smooth structure. Therefore, it is suitable to be used in our cable system to carry the hoist machine.

Other Components

3. Tensile Membrane

Polypropylene is used as the material of the tensile membrane. It is water and stain repellent, resistant to mould, moths and bacteria and is extremely resistant to acids and alkalis. It is also resistant to humidity and weathering. It doesn’t absorb water and dries quickly.

4. End Connections for Tensile Structure

● Cable to steel frame connection

● Foundation connections

U-bolt wire rope clip

Wire rope clips can be used to form a load bearing eye at the end of a cable or wire rope, or to connect two cables together with a lap splice.

Turnbuckle

A turnbuckle is a common rigging device that is used to adjust tension and reduce slack in a rope, cable, or similar tensioning assembly.

The connection can be direct to the foundation or be made with fixing brackets. Fully locked wire ropes are normally bolted with forked sockets to a fixing bracket. The tolerance can be compensated using a mortar layer under the fixing bracket.