山东理工大学：《荷载与结构设计方法》课程教学课件（讲稿，双语）Chapter 3 Water Effect

Chapter 3 Water Effects 3.1 Hydrostatic pressure 3.2 Dynamic water pressure 3.3 Wave load 3.4 Buoyancy 3.5 Ice load 3.6 Impact force 山东理王大军 SHANDONG UNIVERSITY OF TECHNOLOGY

Chapter 3 Water Effects 3.1 Hydrostatic pressure 3.2 Dynamic water pressure 3.3 Wave load 3.4 Buoyancy 3.5 Ice load 3.6 Impact force

3.1 Hydrostatic pressure Hydrostatic pressure Two effects: (1)Chemical effect:corrosion,intrusion,ect (2)Mechanical effect:water pressure 山东理子大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.1 Hydrostatic pressure • Hydrostatic pressure Two effects: (1) Chemical effect: corrosion, intrusion, ect (2) Mechanical effect: water pressure

G 5东理子大军 SHANDONG UNIVERSITY OF TECHNOLOGY

归东理子大名 SHANDONG UNIVERSITY OF TECHNOLOGY

3.1 Hydrostatic pressure ·Hydrostatic pressure静水压力 Po 由于液体性质受大气影响不大，水面及挡水结构物 p=p。+yh 周围都有大气压力作用，处于相互平衡状态，在确 h yh 定液体压强时常以大气压强为基准点。以大气压强 为基准起算的压强称为相对压强，工程中计算水压 力作用时，只考虑相对压强： p=Yh 归东理王大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.1 Hydrostatic pressure 0 pp h = + γ 𝑝𝑝0 𝛾𝛾𝛾 由于液体性质受大气影响不大，水面及挡水结构物 周围都有大气压力作用，处于相互平衡状态，在确 定液体压强时常以大气压强为基准点。以大气压强 为基准起算的压强称为相对压强，工程中计算水压 力作用时，只考虑相对压强: 𝒑𝒑 = 𝜸𝜸𝜸𝜸 • Hydrostatic pressure 静水压力

3.1 Hydrostatic pressure 。Hydrostatic pressure静水压力 Magnitude:increases linearly with depth Direction:always perpendicular to the surface of structural 静水面 、2 778177112 必 777777777 其中(a)、(b)、(c)受压面为平面，(d)受压面为曲面 归东理工大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.1 Hydrostatic pressure • Hydrostatic pressure 静水压力 ▫ Magnitude: increases linearly with depth ▫ Direction: always perpendicular to the surface of structural

3.2 Dynamic water pressure 流速接近0， 压力最大 归东理王大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.2 Dynamic water pressure 流速接近0， 压力最大

3.2 Dynamic water pressure ·Pressure of moving water流水压力 Calculation of water current load on bridge piers Influencing factors: ·current velocity, surface roughness of piers, ·flow pattern ·Shape of piers P=Pv=-rv 22g 的东理王大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.2 Dynamic water pressure • Pressure of moving water 流水压力 ▫ Calculation of water current load on bridge piers  Influencing factors:  current velocity,  surface roughness of piers,  flow pattern  Shape of piers 2 2 2 2 v v P g ρ γ = = =

3.2 Dynamic water pressure ·Pressure of moving water流水压力 Calculation of water current load on bridge piers Assuming impact area is A,by considering the shape coefficient C for pier cross- section: 2g 桥墩形状 方形桥墩 矩形桥嫩（长 圆形桥墩 尖端型桥墩 圆端型桥墩 边与水流平行) c 1.5 1.3 0.8 0.7 0.6 归东理王大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.2 Dynamic water pressure • Pressure of moving water 流水压力 ▫ Calculation of water current load on bridge piers  Assuming impact area is A, by considering the shape coefficient C for pier cross￾section: 2 2 v p CA g γ = 桥墩形状 方形桥墩 矩形桥墩（长 边与水流平行） 圆形桥墩 尖端型桥墩 圆端型桥墩 C 1.5 1.3 0.8 0.7 0.6

3.2 Dynamic water pressure ·Pressure of moving water流水压力 Calculation of water current load on bridge piers Nonlinear increase of current velocity with depth Nearly 0 at river bottom ·For simplification,inverse triangle shaped pressure is assumed(合力位置水 位下1/3水深出). 归东理工大军 SHANDONG UNIVERSITY OF TECHNOLOGY

3.2 Dynamic water pressure • Pressure of moving water 流水压力 ▫ Calculation of water current load on bridge piers  Nonlinear increase of current velocity with depth  Nearly 0 at river bottom  For simplification, inverse triangle shaped pressure is assumed （合力位置水 位下1/3水深出）