Study On Tensile Characteristics Of Beams In RC Frame Structures Supported By Foundations At Different Ground Levels

RC Frame Structures supported by foundations at different ground levels, which is widely applied to civil construction in mountainous cities, is one of the typical mountainous building structures that the bottom of the same structural unit is located at different base levels and the whole frame of ground floors are designed in accordance with the height between floors beneath the highest ground layer. Due to the grounding mode of unequal altitude, the grounding part and the other parts of the ground layer have deformation difference during the earthquake; as a result, beams of the upper ground floor are under the effect of axial force. In addition, the tie-beams where they are set can affect the bearing performance of the structure. According to previous researches, the first layer of the upper ground is the most vulnerable part of the structure, the upper ground poles and beams are susceptible to damage under earthquakes, so the bearing performance of beams in this kind of structure is worthy of being investigated in order to figure out the related ways and measures to improve the bearing capacity of RC Frame Structures supported by foundations at different ground levels.Both this kind of structure with tie-beams and without tie-beams are studied in this paper. Firstly, some characteristics of the structure such as the height, the number of spans and the location of tie-beams were altered. Second, the axial force of beams was analyzed comparatively under the frequently occurred earthquakes, seismic fortification intensity and rarely occurred earthquakes by simulation. Thirdly, the patterns concerning axial force distribution and strength of beams were worked out. Finally, seismic design methods and anti-seismic measures of beams in the structure were put forward.The conclusions of this paper are as follow:① Owing to different earthquake intensity, the beams located in the upper ground layer suffer from large axial force in the structure without tie-beams, while the beams located in the off-layer suffer from large axial force in the structure with tie-beams. Furthermore, as the number of layers and spans increases, the axial force of the beams becomes larger.② Set pull beam is beneficial to improve the connected to the formation of the seismic performance, and set to the beam to pull off a layer of structure effect maximum; and connected to the stratigraphic framework of beams still according to playing design to dual seismic defense role.③ The out layer frame beams tension and the magnitude of the earthquake intensity, should determined by the calculation, not simply in accordance with the foundation beam approach to take; design method is according to the small earthquake for the overall design of the structure and press in elastic shock on the tension frame beam design review. Finally, the anti-seismic measures assurance structures subjected to earthquake damage is not serious.④ The beams of the structure should take tension design into consideration. The concrete reinforcing bars at the beam ends should use long bars in terms of the whole span length and the anchorage length of the side bars fixed on the supports should be calculated in the light of tensile reinforcement.