第11章楼盖-课件.ppt

* Identification Who are you? Create login ID’s to identify users. Authentication Is that really you? Verify identify via password, PIN, biometrics, etc… Authorization Are you allowed to do what you’re trying to do? Role-Based Access Control (RBAC) is used for easy authorization maintenance Confidentiality Assurance that the information is shared only among authorized entities. Use encryption to prevent eavesdropping. Integrity Assurance that the information is accurate, authentic, and complete. Verify that data was not garbled/lost/changed during transmission. Non-Repudiation Records prove that I sent you a message and that you received my message. Verify transactions with receipts, logging, etc… Service Continuity/Availability Assure than information resources are available as expected and service levels can be met. Have plans for backup, disaster recovery, etc... No system can be 100% secure. Security measures combine preventive, defensive, and monitoring tools/techniques. Identify all points of entry/control of the system. For each control point, must identify the potential threats and level of acceptable risk. All new functionality adds more potential security risks 支座按实际情况 无弯矩按简支 无转角按固支 四、双向板肋梁楼盖3. 双向板按弹性理论的内力计算 连续板——利用单跨板的计算表格(条件: ) g g+q g+q/2 +q/2 g+q/2 a) +q/2 b) *跨中最大正弯矩 g g+q 四、双向板肋梁楼盖3. 双向板按弹性理论的内力计算 连续板——利用单跨板的计算表格(条件: ) *支座最大负弯矩 g+q g+q 钢筋屈服后出现塑性铰 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 塑性铰线的概念及其位置的确定方法 钢筋屈服后出现塑性铰线 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 塑性铰线的概念及其位置的确定方法 * 负塑性铰线沿固定边界产生 * 正塑性铰线必通过两块板转动轴的交点（固定边和简支边一般为转动轴，转动轴还通过支承板的柱子） * 塑性铰线出现在弯矩最大处 负塑性铰线 正塑性铰线 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 塑性铰线的概念及其位置的确定方法 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 塑性铰线法的假定 * 板即将破坏时，塑性铰线发生在弯矩最大处； * 分布荷载下，塑性铰线是直线； * 节板为刚性板，板的变形集中在塑性铰线上； * 在所有可能的破坏图示中，必有一个是最危险的，其极限荷载最小； * 塑性铰线上只有一定值的极限弯矩，没有其它内力。 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 双向板的极限荷载（以四边固定板为例） 假定双向板的破坏图示 虚功原理求极限荷载 发生虚位移 ? 四、双向板肋梁楼盖4. 双向板按塑性理论的内力计算——塑性铰线法 l01/2 l01 l02