1A- Easy introduction to Tension members-part-2.

Introduction to Tension members-part 2.

For tension members, since there are different types of steel materials with different grades and different ASTM designations.

It is important to understand the types of materials. In this post, a review of AISC table 2-4 is given and the differences between the construction manuals CM#14 and CM #15 are listed. Some materials are removed from AISC table 2-4 based on CM#15 and a lot of materials are added.

How to estimate the net area of tension members?

Prior to viewing AISC table 2-4 in CM#14, we will start a new subject which is the gauge distances if we have one angle with four bolted connections that are arranged in two-gauge lines.

 Assume that the applied tension force acts in the centroid of the angle.  The first and second line of fasteners is in the direction of the applied tension force. The first gauge line has two fasteners, the same as the second gauge line; the vertical distance between the two-gauge lines is called gage distance, denoted by g. The gage distance is perpendicular to the direction of the tension force.

While the distance between fastens or spacing, in the direction of the force, is called pitch, the pitch is parallel to the gauge lines. The inclined distance joining between the two fasteners shown as D1 has a horizontal distance in pitch distance S1, while the vertical distance component is gage g.

The edge distance is termed ED1 which is from the center of a hole to the nearest edge that distance is the horizontal distance. While the vertical distance from the end of the angle to the second gauge line is given as ED2.

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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 mentioned that long-used practice to punch holes with 1/16 inch diameter larger than that of the bolts.

Actually, when this practice was followed, the punching of a hole was assumed to damage or destroy 1/16 inch more of the surrounding metal. Then in practice is to consider 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.

For carbon steel, we have five groups starting from ASTM A36, ASTM A 53 Grade b, and ASTM A500, which has two items grade b and Grade C.

Followed by ASTM A501, with grades A and b, and finally ASTM A 592 C with grades 50 and grade 55.

If we have a look at the marked black square, which are the preferred material specification?

We have A36 with Fy=36 ksi and Fu=58-80 ksi is preferred for M section, S section, Mc section, and L shape.

The hollow section group HSS consists of three items, which are 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.

While for the round HSS its preferred ASTM A is ASTM A 500 grade B with Fy=42 ksi and ultimate stress Fu=58 ksi.

For the rectangular HSS ASTM A 500 grade B with Fy=46 ksi and ultimate stress Fu=58 ksi.

The Gray squares are for others available in grades and can be used if specified. This includes ASTM A500 grade C, and ASTM A501 grade A & b for HS sections.

 The white square is for the material specification that does not apply.

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 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 yield stress Fy=60 ksi and ultimate stress Fu=60 ksi.

While grade 65 has a yield stress of 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.

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.

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In the next slide, we will continue with table 2-4, with the heading applicable ASTM specifications for various structural shapes based on CM#14.  

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.

We see ASTM A572 for example, starting from grade 42 to 65, has five grades so the required grade must be specified.

An example of ASTM A 242 is a corrosion-resistant High strength-low 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

Applicable ASTM specifications for shapes table 2-4 for various shapes-CM#15.

In the next slide, from Construction manual CM#15, we will explore the different types of steel.

Carbon steel-AISC table 2-4 for plates-CM#15.

For carbon steel, we have eight groups, with a new three groups added which are ASTM A709, ASTM A1043 d, and ASTM A1085. If we have a look at the marked black square, which are the preferred material specification? We have A36 with Fy=36 ksi and Fu=58-80 ksi is preferred for the M section, S section, Mc section, and L shapes same as the construction manual number 14.

The hollow section group HSS consists of three items, which are 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.

While for the round HSS, its preferred ASTM A has changed from ASTM A 500 grade b and becomes ASTM A 500 grade C with Fy=46 ksi and ultimate stress Fu=62 ksi with higher Fy and Fu values.

For the rectangular HSS its preferred ASTM A has changed from ASTM A 500 grade b and becomes ASTM A 500 grade C with Fy=50 ksi and ultimate stress Fu=62 ksi with higher Fy and Fu values.

The old ASTM A 500 grade b has become with gey colors.

Added ASTM A grades in CM#15 in table 2-4.

The added ASTM A709 grade 36 with Fy=36 ksi and ultimate stress Fu has a range of 58 to 80 ksi with a symbol which stands for wide flange thickness bigger than 3 inches only the minimum 58 ksi applied.

For the added ASTM A 1043 d,k,  with two grades grade 36 and grade 50.d for shape profile with a flange width of 6 inches or greater. Symbol k stands for This specification is not a prequalified base metal per AWS D1.1.

For ASTM A 1085 with grade A, the yield stress Fy=50 ksi and Fu=65 ksi.

This grade is marked grey color for the HSS section.

For ASTM A 36 its yield stress is 36 ksi and the ultimate stress is Fu=58-80 ksi. The symbol b is for shapes over 426 lb/ft. For the high strength low alloy, for the w section, it is preferred to use ASTM A992 the start yielding Fy equals 50 ksi, and ultimate stress Fu=65 ksi.

Item c shown for A529 C, is for shapes used as less or equal 11/2 inch only. The symbol d appears for ASTM 572 Gr-50, where Fy =50 ksi and Fu equals 65 ksi, but 70 ksi can be specified.

High strength-alloy steel-AISC table 2-4 for plates-CM#15.

For the high-strength alloy, according to CM#15, there is a total of six groups.

A new ASTM A 709 was added with three grades Grade 50, grade 50s, and grade 50W. Another ASTM A 1065k was added with three grades, grade 50i  with symbol k which means that it can be considered corrosion resistant as well with yield stress Fy=50 ksi and Fu=70 ksi it has a grey marking for a rectangular  HSS section.

Corrosion-resistant grades in CM#15 in table 2-4.

ASTM A 242 was removed from the corrosion-resistant table of ASTMA and a new ASTM A 1065 k was added with Fy=50 ksi and Fu=70 ksi.  Symbol k stands for This specification is not a prequalified base metal per AWS D1.1.

This is the Grouping of the different types of steel Grades based on CM#15.

Table A3.1 for the listed material from the new specification.

Table A3.1 from the new specification for the used ASTM A used. The ASTMA list was tabulated with the corresponding yield stress in both imperial and metric included.

For the other, long leg r leg we have gauge distances g1 and g2 their distances are shown for the various leg distance. Starting from 8 inches descending to 1-inch length, descending to 1-inch length, and g from 5/8 for a 1-inch angle to 4.5 inches, and the values for long leg with two gauge lines for g1 from 3 to 2 inches

Practice problem for ASTM A24.

ASTM A 242 is specified to be used for a beam with W24x192, it is required to find the values of the yield stress Fy and Fu for the beam and the modulus of elasticity, this practice problem is given for CM#14 only. As a reminder, A242 was used as corrosion resistant in table 2-4 and later removed from CM#14 for corrosion resistance, it was available for the W section, and has a grey color.

Now it is used for plates. It has three grades 42, 46, and 50 ksi for yield stress which are marked J,k, and l based on the flange thickness.

Based on table 1-1, the flange thickness is 1.46 inches which is less than 1.50 inches, we will select grade 50 category L, and the ultimate stress Fu is specified as 70 ksi. The modulus of elasticity is 29×10^6 psi.

The next post-contains-Review of AISC table 2-5 for plates.

For a useful external link-Chapter 3 – Tension Members– Bartlett Quimby.