def calc_crit_span(sl,
fd,
vertical_load,
ip_axis='length',
verbose=0,
**kwargs):
"""
Determine the size of a footing given an aspect ratio and a load
:param sl: Soil object
:param vertical_load: The applied load to the foundation
:param fos: The target factor of safety
:param length_to_width: The desired length to width ratio of the foundation
:param verbose: verbosity
:return: a Foundation object
"""
method = kwargs.get("method", 'vesic')
# Find approximate size
new_fd = models.RaftFoundation()
new_fd.width = fd.width
new_fd.depth = fd.depth
new_fd.length = fd.length
prev_ub_len = fd.length
q_ult = capacity_method_selector(sl,
new_fd,
method,
verbose=max(0, verbose - 1))
init_fos = (
q_ult *
fd.area) / vertical_load # TODO: should this have overburden pressure?
if init_fos < 1.0:
raise ValueError
prev_lb_len = 0 # should be FOS lower than 1.
l_ip = getattr(fd, ip_axis)
est_len = l_ip / init_fos
prev_q = q_ult
for i in range(50):
setattr(new_fd, ip_axis, est_len)
q = capacity_method_selector(sl,
new_fd,
method,
verbose=max(0, verbose - 1))
curr_fos = (q * new_fd.area) / vertical_load
if np.isclose(curr_fos, 1.0, rtol=0.01):
break
elif curr_fos < 1:
prev_lb_len = est_len
est_len = (prev_ub_len + est_len) / 2
else:
prev_ub_len = est_len
est_len = (prev_lb_len + est_len) / 2
if i == 49:
raise ValueError(init_fos, curr_fos, est_len, prev_lb_len, prev_ub_len)
return est_len
def test_calc_m_eff_via_loukidis_and_salgado_2006():
# pg 451
fd = models.RaftFoundation()
fd.width = 2
fd.length = 3
fd.depth = 0.0
sl = models.Soil(unit_dry_weight=17.1e3)
m_eff_expected = 742.0 # kPa
m_eff = geofound.calc_m_eff_bc_via_loukidis_and_salgado_2006(
sl, fd, p_atm=100.0e3) / 1e3
assert np.isclose(m_eff, m_eff_expected, rtol=0.01), m_eff
def size_footing_for_capacity(sl,
vertical_load,
fos=1.0,
length_to_width=1.0,
verbose=0,
unit_weight=0,
**kwargs):
"""
Determine the size of a footing given an aspect ratio and a load
:param sl: Soil object
:param vertical_load: The applied load to the foundation
:param fos: The target factor of safety
:param length_to_width: The desired length to width ratio of the foundation
:param verbose: verbosity
:return: a Foundation object
"""
method = kwargs.get("method", 'vesic')
depth_to_width = kwargs.get("depth_to_width", 0)
depth = kwargs.get("depth", 0)
use_depth_to_width = 0
if not depth:
use_depth_to_width = 1
# Find approximate size
fd = models.RaftFoundation()
fd.width = .5 # start with B=1.0m
for i in range(50):
fd.length = length_to_width * fd.width
if use_depth_to_width:
fd.depth = depth_to_width * fd.width
else:
fd.depth = depth
capacity_method_selector(sl, fd, method)
q = fd.q_ult
bearing_capacity = q * fd.length * fd.width
fs_actual = bearing_capacity / (vertical_load +
unit_weight * fd.area * fd.depth)
if fs_actual < fos:
# Need to increase foundation sizes
fd.width += 0.5
else:
if verbose:
log("fs_actual: ", fs_actual)
log("fd.width: ", fd.width)
break
# at this stage the current size should be too big
width_array = []
fs_array = []
for j in range(11):
width_array.append(fd.width)
fd.length = length_to_width * fd.width
if use_depth_to_width:
fd.depth = depth_to_width * fd.width
capacity_method_selector(sl, fd, method)
q = fd.q_ult
capacity = q * fd.length * fd.width
fs_array.append(capacity /
(vertical_load + unit_weight * fd.area * fd.depth))
fd.width = fd.width - 0.5 / 10
# search the array until FS satisfied:
if verbose:
log("reqFS: ", fos)
log("width array: \n", width_array)
log("FS array: \n", fs_array)
for fs in range(len(fs_array)):
if fs_array[fs] < fos:
fd.width = width_array[fs - 1]
fd.length = length_to_width * fd.width
if use_depth_to_width:
fd.depth = depth_to_width * fd.width
capacity_method_selector(sl, fd, method)
break
if fs == len(fs_array) - 1:
DesignError("No suitable foundation sizes could be determined!")
return fd