Introduction to Tension members-part 2.
Tension members require several types of steel materials with varying grades and ASTM designations. It is critical to grasp the different types of materials.
This page provides a study of AISC table 2-4 and lists the differences between the construction manuals CM#14 and CM#15. Based on CM#15, certain materials are removed from AISC table 2-4, while many others are added.
How to estimate the net area of tension members?
The next topic is gauge distances if we have a single angle with four bolted connections arranged in two gauge lines.
Assume the applied force acts at the angle’s centroid.
The first and second lines of fasteners run in the same direction as the applied force.
The first gauge line, like the second gauge line, has two fasteners; the vertical distance between the two gauge lines is known as the gage distance, and it is represented by the symbol g. The gage distance runs perpendicular to the direction of the force.
Pitch refers to the distance between fasteners or spacing in the direction of the force, and it is parallel to the gauge lines.
The inclined distance joining between the two fasteners denoted as D1, has a horizontal distance in pitch distance S1, while the vertical distance component is gage g.
The edge distance is known as ED1, and it is measured from the center of a hole to the nearest edge. This value is the horizontal distance.
The vertical distance between the end of the angle and the second gauge line is denoted as ED2.
We can get the net width which depends on the route of bolts, if our section is vertical we will deduct the hole diameters from the vertical width depending on the number of bolts we face.
To get the net width while working with a zigzag line distance between the bolts, add S^2/4g, where g is the transverse distance, and S is the longitudinal distance as a center-to-center spacing and deduct the hole diameters for bolts that the section is cutting.
Looking back to Prof McCormack’s notes, he stated the long-standing practice of punching holes with a 1/16 inch diameter larger than the bolts.
When this technique was followed, it was expected that punching a hole would harm or destroy an additional 1/16 inch of the surrounding metal. In actuality, add 1/16+1/16 inch to the diameter of the bolt.
Applicable ASTM specifications for structural shapes- AISC table 2-4.
In the next slide, we have AISC table 2-4, with the heading applicable ASTM specifications for various structural shapes. From Construction manual CM#14.
Carbon steel-AISC table 2-4 for plates-CM#14.
Carbon steel is classified into five categories, beginning with ASTM A36, ASTM A53 Grade B, and ASTM A500, which includes two grades: B and C.
ASTM A501 has grades A and B, followed by ASTM A 592 C, which has grades 50 and 55.
What are the preferred material parameters based on the marked black square?
A36 with Fy=36 ksi and Fu=58-80 ksi is ideal for M, S, Mc, and L shapes.
The hollow section group HSS includes three items: rectangular HSS, round HSS, and pipe.
The preferred ASTM A for pipe is ASTM A 53 grade B, with Fy=35 ksi and ultimate stress Fu=60 ksi.
For round HSS, the preferred ASTM A is ASTM A 500 grade B with Fy=42 ksi and ultimate stress Fu=58 ksi.
For rectangular HSS ASTM A 500 grade B, Fy=46 ksi and ultimate stress Fu=58 ksi.
The gray squares are for other potential grades and can be utilized if requested. This comprises ASTM A500 grade C and ASTM A501 grades A and B for HS sections.
The white square for the material specification is not applicable.
High strength-alloy steel-AISC table 2-4 for plates-CM#14.
For the high-strength alloy, according to CM#14, there are four groups including ASTM A 572, with five grades in which grade 50 is preferred for the HP section with yield stress Fy=50 ksi and fu=65 ksi, we have symbol d, which means that maximum tensile strength of 70 ksi can be specified.
Also, we have symbol e for both grades 60 and 65 for which grade 60 has a yield stress Fy=60 ksi and ultimate stress Fu=60 ksi.
While grade 65 has a yield stress Fy=65 ksi and ultimate stress Fu=65 ksi. E for flange thickness of less or equal to 2 inches only.
ASTM A 618 f, with grade I and grade ii, with yield stress Fy=50 ksi and Fu=70 ksi, the symbol f stands for it can be specified as corrosion resistant.
For ASTM A-913 comes in four grades, the first grade 50 with Fy=50 ksi with symbol g which indicates that the minimum fy pf 50 ksi
to be applied with walls nominally ¾ inches and Fu=60 with symbol h , which indicates that the ultimate stress can be raised to 65 ksi and a maximum yield to tensile stress strength ratio of 0.85 can be specified.
For ASTM A 992 which is preferred for the W section, it has yield stress Fy=50 ksi and ultimate stress Fu=65 ksi with symbol I which stands for maximum yield to tensile stress strength ratio of 0.85, and carbon equivalent formula is included as mandatory in ASTM A992.
.
Corrosion resistant high strength low alloy-AISC table 2-4 for plates-CM#14.
For the corrosion resistant high strength low alloy. There are three categories ASTM A 242 with three grades 42,52 and 60 and with Fu from 63 to 70 ksi.
We have symbols j, K, and L. The symbols J, K, and L are related to the shapes with flange thickness. For j is for flanges with a thickness greater than 2 inches only.
The specified Fy equals 42 ksi and the ultimate stress is 63 ksi. For K for flange, thickness is >1.5 inches and less or= 2 inches only. The specified Fy equals 46 ksi and the ultimate stress is 67 ksi.
L is for flanges thickness less than or equal to 1.50 inches only. The specified Fy equals 50 ksi and the ultimate stress is 70 ksi. The second group is for ASTM A 588 with Fy=50ksi and Fu=70 ksi.
This is a quote From Prof. Segui‘s book from the 5th edition, you can find values of Fy and fu for various structural steel in Table 2-4, the black areas correspond to preferred materials, and the grey regions present other steels that are available in other ASTM grades.
ASTM A572 contains five classes, ranging from 42 to 65, hence the required grade must be given.
An example of ASTM A 242 is a corrosion-resistant High-strength alloy. In order to specify the required Fy and Fu there are different symbols arranged based on the flange thickness, the symbols are to L
For W33x221 with ASTM A242 L is specified based on the flange thickness which is 1.28 inches.
The next posts :Introduction to Tension members-part-3 and –Review of AISC table 2-5 for plates.
For a useful external link-Chapter 3 – Tension Members– Bartlett Quimby.
