[abstract]: This design for the Jingyang County national tax office building design, the structure system for the cast-in-place reinforced concrete portal frame construction, the total floor space 5000 square meters, the earthquake fortification intensity is 7 degrees, the location category for the kind, the structure earthquake resistance rank for second-level, uses the crosswise frame load-bearing system. Design content including architectural design, structural design two parts. And the structural design is the design key point, when structural design, after determination portal frame construction plane layout, selected a pin frame to carry on the computation. First determined that frame Liang, the column section size, the computation line rigidity, then calculates the gravity load, then from shakes using the apex deflection method computation structure the cycle, calculates, under permanently the live load function Liang, column's endogenic force, carries on the frame endogenic force combination again, the section design and the reinforcing bars computation, finally has carried on the staircase, the floor and the foundation design. And has drawn up the construction drawing and the structure construction drawing according to the computed result. [key word] office building design Portal frame construction Endogenic force computation endogenic force built-up section design aseismic design