What Is a Suspension Cable?

Suspension cable A cable that carries a load between two suspension points. Each point in the suspension cable can only bear the tension, and the tension at each point is along the tangential direction of the suspension cable at that point. The main cable and power lines of the suspension bridge are suspension cables.

Suspension cable A cable that carries a load between two suspension points. Each point in the suspension cable can only bear the tension, and the tension at each point is along the tangential direction of the suspension cable at that point. The main cable and power lines of the suspension bridge are suspension cables.

Chinese name

Suspension cable

Foreign name

suspended cable

Introduction to Suspension

A cable that carries a load between two suspension points. Each point in the suspension cable can only bear the tension, and the tension at each point is along the tangential direction of the suspension cable at that point. The main cable and power lines of the suspension bridge are suspension cables.

Analysis of suspension cable characteristics

Because the advantage of the suspension cable is that each point only bears tension and no bending moment, the analysis of the force is relatively simple.

The design is simple and reliable, and can fully utilize the properties of steel to achieve the economic effect of saving materials and reducing weight. The cable suspension structure has been widely used in some large-span building structures in modern times. For example, for a suspension bridge, the two suspension points A and B of the main cable AB are of equal height, and the load on the bridge deck is transmitted to the main cable through the uniformly distributed slings (Figure 1). The horizontal distance l between A and B is called the span. Suppose the load on the horizontal length per unit

The magnitude of the load is q , and the coordinate system Oxy is taken as shown in Figure 1. Ignore the deadweights of the suspension cables and slings. In the suspension cables, any micro-segment CD with a length of x projected on the x- axis can be selected. The equilibrium under the action of x thus satisfies the following equilibrium equation:

By analogy, it can be seen that the horizontal component of the cable tension at each point is H , so:

or

It can be obtained that the deflection shape of the suspension cable is a parabola, and the equation is:

Tension at any point in the suspension cable:

The tension of the suspension cable is the lowest at the lowest point O , T _{x = 0} = H ; the tension at the suspension point is the largest,

The vertical distance between the lowest point of the suspension cable and the suspension point is called sag, and its value

For a suspension cable whose load is evenly distributed along the cable length, such as the transmission line AB , the load on the unit cable length is q . Take any micro-segment CD with length s in the suspension cable, and the vertical load acting on s is q s , then the equilibrium equation (1) becomes:

The horizontal balance equation is the same as (2). So the differential equation of this suspension cable is:

because

So d T = q d y . The tension at any point in the suspension cable is: T = qy + H, where y is the ordinate of the point. It can be seen that the tension at the two suspension points is the largest. If the origin of the selected coordinate system is at the lowest point of the suspension cable, then the solution of (5) is:

Where C = H / q is a constant; H is the tension of the suspension cable at the lowest point O. Its tortuous shape is called catenary. Expanding the right side of equation (6) into series, there are:

If the first term on the right side of the above formula is taken as the approximate value, then

, Is a parabola. Many countries

Home uses "parabola" as the theory of suspension cable calculation. When the central deflection coefficient n = f ₀ / l ₀ (Figure 3) is increased to 0.08, the error of this theory increases significantly. In the 1960s, due to the needs of the design of suspension cables such as long-span single-span cableways, suspended roof structures, and long-span bridges, Chinese scholars intercepted the binomial from (7) as the second approximation theory. The suspension curve is a quartic algebraic equation:

Compared with the existing "parabola" theory, the modified suspension cable calculation theory can expand the calculation range by about two times. ^[1-2]