How to calculate the control force outside the anchor
2. The corresponding maximum torque is 80KN × 22mm × 0.39=686.4N·m
Control stress x total cross-sectional area of steel strand = tension control force. The relationship between control stress and control force is linear regression, and the condition is within the elastic range, that is, not more than 0.8x1860
There are differences between the two in reading mode, application range and the essence of force
The control stress under the anchor: the control stress outside the anchor is corresponding to the oil meter reading of the jack (the control reading of the oil meter is to bring the external tension of the anchor into the equation of roof calibration)control stress outside the anchor: the control stress under the anchor is the control stress at the beginning of the calculation of the steel strand, that is, the control stress outside the anchor minus the loss of the anchor mouth (generally, the loss of the anchor head is taken as 6%)
Control stress under anchor: the control stress under anchor is the value of control stress outside the anchor minus the loss of anchor mouth at the tension end, which is generally taken as 6% according to the design. Namely: control stress outside anchor = control stress under anchor / (1-6%)control stress outside anchor: in actual tension, control stress outside anchor should be adopted
The essence of force is the real force acting on the prestressed reinforcement after considering the pipe friction coefficient and deviationcontrol stress outside anchor: it is the standard to calculate the tension force ring tension, and the stress of prestressed reinforcement with different yield strength is different
extended data
construction design control tension of steel strand prestressed tension refers to the tension of steel strand in front of anchor fixture after prestressed tension. Therefore, in the calculation of the theoretical elongation of the prestressed tension of the steel strand, the distance between the anchor points at both ends of the steel strand should be taken as the calculation length of the steel strand
However, the control tension of the steel strand is controlled at the jack tool anchor ring the prestressing tension, so for the convenience of control and calculation, the distance between the anchor points at both ends of the steel strand and the working length of the steel strand in the tension jack are generally taken as the calculation length of the theoretical elongation of the prestressing tension of the steel strandring the prestressing tensioning of steel strand, most of the exposed part of steel strand is wrapped by anchorage and Jack, so the stretching elongation of steel strand can not be directly measured on steel strand, so the stretching elongation of steel strand can only be calculated by measuring the piston stroke of tensioning jack, but the anchor plug retraction in the whole process of steel strand tensioning should also be reced
Control stress x total cross-sectional area of steel strand = tension control force. The relationship between control stress and control force is linear regression, and the condition is within the elastic range, that is, no more than 0.8x1860
both the control stress and the tension force outside the anchor are corresponding to the oil meter reading of the jack (the control reading of the oil meter is to bring the tension force outside the anchor into the equation of roof calibration). The control stress under the anchor is the control stress at the beginning of the calculation of the steel strand, that is, the control stress outside the anchor minus the loss of the anchor mouth (generally, the loss of the anchor head is taken as 6%)
the equation of top calibration is actually the relationship between the force of LKN when the jack is calibrated and the reading of one grid on the dial
In other words, the external control stress of the anchor is the value on the oil pressure gauge divided by the area of the steel bundle, and the control stress under the anchor is the value of the external control stress of the anchor after decting the loss of the anchor head
extended data:
the value of tension control stress is related to the method of prestressing. For the same steel grade, the value of pretensioning method is higher than that of post tensioning method. This is because the pre tensioning method and post tensioning method have different ways to establish prestress. Pretensioning method is to tension the steel bar on the pedestal before pouring concrete, so the tension stress established in the prestressed steel bar is the tension control stress σ con
the post tensioning method is to tension the steel bar on the concrete member. At the same time, the concrete is compressed. The tension control stress indicated by the jack of the tensioning equipment has dected the steel bar stress after the elastic compression of the concrete. For this reason, the design of post tensioned component is very important σ Con value should be lower than pretension method
The determination oftension control stress value is also related to the steel grade of prestress. As the prestressed concrete is made of high-strength steel bars, its plasticity is poor, so the control stress can not be too high
There are differences between the two in reading mode, application range and the essence of force
The control stress under the anchor: the control stress outside the anchor is corresponding to the oil meter reading of the jack (the control reading of the oil meter is to bring the external tension of the anchor into the equation of roof calibration)control stress outside the anchor: the control stress under the anchor is the control stress at the beginning of the calculation of the steel strand, that is, the control stress outside the anchor minus the loss of the anchor mouth (generally, the loss of the anchor head is taken as 6%)
Control stress under anchor: the control stress under anchor is the value of control stress outside the anchor minus the loss of anchor mouth at the tension end, which is generally taken as 6% according to the design. Namely: control stress outside anchor = control stress under anchor / (1-6%)control stress outside anchor: in actual tension, control stress outside anchor should be adopted
The essence of force is the real force acting on the prestressed reinforcement after considering the pipe friction coefficient and deviationcontrol stress outside anchor: it is the standard to calculate the tension force ring tension, and the stress of prestressed reinforcement with different yield strength is different
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extended data:
classification
(1) according to the use of classification
prestressed steel strand, (power) galvanized steel strand and stainless steel strand, in which the prestressed steel strand coated with anti-corrosion grease or paraffin HDPE is called unbonded steel strand, Prestressed steel strand is also made of galvanized or galvanized aluminum alloy steel wire
(2) steel strand, aluminum clad steel strand and stainless steel strand are classified according to material characteristics
(3) according to the structure classification
according to the number of steel wires, prestressed steel strand can be divided into 7 wires, 2 wires, 3 wires and 19 wires, and the most commonly used structure is 7 wires
the galvanized steel strand and aluminum clad steel strand used for electric power are also divided into 2, 3, 7, 19, 37 and other structures according to the number of steel wires, and the most commonly used structure is 7 wire structure
(4) according to the classification of surface coating layer, it can be divided into (smooth) steel strand, galvanized steel strand, epoxy coated steel strand, aluminum clad steel strand, copper-plated steel strand, plastic clad steel strand, etc