app.py

import streamlit as st
import numpy as np
import matplotlib.pyplot as plt

# Function to compute reactions and shear and moment diagrams
def compute_beam_analysis(L1, L2, w, E, I):
    # Reactions at supports
    R1 = (w * L2 * (2 * L1 + L2)) / (2 * (L1 + L2))
    R2 = (w * L1 * (2 * L2 + L1)) / (2 * (L1 + L2))

    # Position vectors
    x1 = np.linspace(0, L1, 100)
    x2 = np.linspace(L1, L1 + L2, 100)

    # Shear force calculation
    V1 = R1 - w * x1  # For the first span
    V2 = R2 - w * (x2 - L1)  # For the second span

    # Bending moment calculation
    M1 = R1 * x1 - 0.5 * w * x1**2  # For the first span
    M2 = R2 * (x2 - L1) - 0.5 * w * (x2 - L1)**2  # For the second span

    return x1, x2, V1, V2, M1, M2


# Streamlit App Layout
st.title("Two Span Beam Analysis")

st.sidebar.header("Input Parameters")
L1 = st.sidebar.number_input("Length of Span 1 (L1) [m]", min_value=1.0, value=5.0)
L2 = st.sidebar.number_input("Length of Span 2 (L2) [m]", min_value=1.0, value=5.0)
w = st.sidebar.number_input("Uniform Load (w) [N/m]", min_value=1.0, value=10.0)
E = st.sidebar.number_input("Modulus of Elasticity (E) [Pa]", min_value=1e3, value=2e11)
I = st.sidebar.number_input("Moment of Inertia (I) [m^4]", min_value=1e-6, value=1e-4)

# Calculate
x1, x2, V1, V2, M1, M2 = compute_beam_analysis(L1, L2, w, E, I)

# Plot Shear Force Diagram (SFD)
fig, ax = plt.subplots(1, 2, figsize=(12, 6))

# Shear Force Diagram
ax[0].plot(x1, V1, label="Span 1", color='blue')
ax[0].plot(x2, V2, label="Span 2", color='green')
ax[0].axhline(0, color='black',linewidth=0.5)
ax[0].set_xlabel("Position along the beam (m)")
ax[0].set_ylabel("Shear Force (N)")
ax[0].set_title("Shear Force Diagram (SFD)")
ax[0].legend()

# Plot Bending Moment Diagram (BMD)
ax[1].plot(x1, M1, label="Span 1", color='blue')
ax[1].plot(x2, M2, label="Span 2", color='green')
ax[1].axhline(0, color='black',linewidth=0.5)
ax[1].set_xlabel("Position along the beam (m)")
ax[1].set_ylabel("Bending Moment (Nm)")
ax[1].set_title("Bending Moment Diagram (BMD)")
ax[1].legend()

# Show the plots
st.pyplot(fig)

# Display results
st.subheader("Reactions at Supports")
st.write(f"Reaction at support A (R1): {R1:.2f} N")
st.write(f"Reaction at support B (R2): {R2:.2f} N")