无粘结部分预应力砼梁斜截面抗裂剪力计算

笔者依据３５片梁的试验资料，着重分析了剪跨比，预应力度对梁斜截面抗裂剪力的影响，在理论分析和数据统计的基础上，提出了一个无粘结Ｐ．Ｐ．Ｃ梁斜截面抗裂剪力的计算公式，公式具有概念清晰，形式简单的特点，并且有一定精度，可为工程设计和进一步的研究提供参考．

Research on the Construction Characteristics of Stone-Built Folk Houses in Jiarong Tibetan Area <br/>—Take the Stone-Built Houses in Xisuo Village as an Example

The Jiarong Tibetan traditional residence is a characteristic regional architecture, located in a high-intensity, high-altitude and cold area, with geographic identification, and is a typical representative of this ethnic group. It has also become an important tourist destination and has important research value. The research used the methods of field survey surveying and mapping to conduct field survey and surveying on 20 buildings in Xisuo Village, a traditional village in the Jiarong Tibetan area. Measure building plans, elevations, and building sections, and collect measurement data for statistical analysis. The results show that the average total height of the building is 10.08 m, the average total building span is 12.44 m, the average total depth is 10.87 m, and the squareness is 0.87. The square shape of the building is more in line with the seismic requirements of high-intensity areas and the local terrain environment. The maximum window-wall ratio in the building is 0.18 south for the second floor, and 0.025 west for the first floor. Smaller window-to- wall ratios have better adaptability to high-altitude cold areas. The height of the building beam section is generally from 0.17 m to 0.32 m, and the average Beam span-depth ratio is 0.10. The building space construction has a good match with the properties of wood materials. These conclusions quantitatively analyze the characteristics of stone-built houses in high-intensity, high-altitude and cold areas, supplement the research on ethnic regional architecture, and provide materials and references for the design, repair and update of related buildings.

Ultimate stress increase in unbonded tendons in prestressed concrete beams

Since the assumption of plane sections cannot be applied to the strain of unbonded tendons in prestressed concrete beams subjected to loadings,a moment-curvature nonlinear analysis method is used to develop analytical programs from stress increases in unbonded tendons at the ultimate limit state.Based on the results of model testing and simulation analysis,equations are proposed to predict the stress increase in tendons at the ultimate state in simple or continuous beams of partially prestressed concrete,considering the loading type,non-prestressed reinforcement index βp,prestressing reinforcement index βs,and span-depth ratio L/h as the basic parameters.Results of 380 beams studied here and test results for 35 simple beams obtained by the China Academy of Building Research were compared with those from prediction equations given in codes and other previous studies.The comparison reveals that the values predicted by the proposed equations agree well with experimental results.